The generator onboard, being the powerhouse of the ship, requires regular maintenance and overhauling to ensure efficient and safe operations. A responsible marine engineer will never wait to carry out maintenance procedures until its machinery is on the edge of a breakdown. Instead, he/she will take all necessary precautions to prevent his ship from any impending troubles, which can take place because of engine room machinery failure or breakdown.

There is a thin line between the starting of a problem and the problem taking the shape of a major issue.  It is only a ship’s engineer who can assess this situation.

Still, cases are observed every year wherein the auxiliary engine breakdown occurs even after giving several indications, foreboding the unfortunate.

Listed below are ten cases wherein you must immediately start the standby engine and stop the auxiliary engine in “trouble” before a dangerous situation takes shape of a major disaster:

1. Abnormal/ Queer Sound: The ship’s generator engine comprises of heavy oscillating and moving parts. The attached auxiliaries such as turbochargers, pumps etc. are also high-speed machines which produce a good amount of sound. Any abnormal sound, no matter how faint, must never be ignored. In case of an unusual sound, the engine should be immediately stopped and troubleshooting must be carried out.

Incorrect Approach: The engine room is equipped with hundreds of machinery systems. When the power-plant is in operation, sounds from other machinery can suppress an abnormal sound. Even if you hear something unusual from the generator, you may think it’s coming from nearby environment or machinery. Never ignore even the slightest abnormal sound. Take a second opinion and stop the engine for checks.

2. Smoke: When you see smoke coming from or near the generator, it’s high time to stop the generator immediately. No need to offload the generator as the situation has already passed the danger level. Use the emergency stop button provided in a local or remote station. Smoke can be due to friction between moving parts, overheating etc.

Incorrect Approach: PANIC is the first thing that will strike a person when smoke or fire is seen. It might reduce the engineer’s thinking process, which will eventually slow down the approach.

Never panic in such situation. Use the remote start button for the standby generator, which will come on-load almost immediately (normally done through local), and emergency stop the running generator.

3. Unusual Lubricating Oil Parameters: If the lubricating oil temperature has increased beyond normal or the oil pressure has dropped below the adequate level, stop the generator immediately and find out the troubling issue, which might be a dirty lube oil cooler or chocked filter.

Incorrect Approach: If you noticed a drop in pressure, the first thing comes to mind is to change to standby filter. If your standby filter is not primed and put in service in running condition, due to airlock major bearing damages can occur. It’s always better to stop the machinery and then change it to standby filter, only after priming the same.

4. Higher Differential Pressure: Differential pressure is a term used to assess the condition of lube oil filter by providing a pressure measurement before and after the filter. The difference between the before and after filter pressures is displayed by a gauge. If the differential pressure is in the higher range, stop the generator and change to standby filter.

Incorrect Approach: On numerous occasions, it has been observed that the generator is allowed to run even when the differential pressure alarm is sounded during maneuvering. Engineers usually prefer not to take risk of changing the filter in running condition, as it may lead to blackout if the filter does not perform correctly. They thus plan to change it once the maneuvering is over.  However, due to this sometimes the differential pressure increases further and there is a sudden drop in oil pressure, which trips the generator in between maneuvering. It is very much possible to find bearing metal particles when filters are opened for cleaning. This shows that most of the times engineer is aware of the filter problem but fail to see the bigger picture.

5. Overspeed: Generator is a high-speed machinery and over-speeding of generator engine has resulted in explosions and causality in the past. Over-speeding of the generator is caused mainly due to a problem in the fuel system, specifically malfunction of the governor. If the generator is running above its rated speed and still does not trip (Read about overspeed trips here), engineers must stop the generator immediately to avoid a major accident. Crankcase inspection and renewal of bottom end bolts is then to be carried out.

Incorrect Approach: During trial running of generator after overhauling, the governor droop is altered to get required speed as stated in the manual. It may happen that the generator over-speeds due to wrong setting or due to stuck fuel rack during this time. Cases of not checking the crankcase and not renewing the bottom end bolts are common causes which lead to bearing damages.

6: Cooling Water Supply: Cooling water supply is an essential entity to ensure a smooth running of all high temperature moving parts. If there is no cooling water supply due to the failure of pumps, the generator should be stopped immediately to avoid overheating damage.

Incorrect Approach: If there is no cooling water pressure in the line, sometimes engineers try to release air from the purging cock provided near the expansion tank line of the generator. If the water supply is not available (due to the failure of supply pump), it will lead to further increase in the temperature and stopping of the generator at a later stage, resulting in the seizure of moving parts. Always stop the generator first and then do the troubleshooting. Once the generator is stopped due to starvation of water, flywheel should be rotated with lubrication to avoid seizing of parts.

7: Leakage from Pipings: If any leakage is found from the fuel, lube oil or cooling water pipe, it is to be rectified only after stopping the generator. This will allow the engineer to tackle the leakage easily and better maintenance can be carried out.

Incorrect Approach: If there is a small fuel oil or a water leak from any of the pipe connections, tightening of the connection may stop the leak but over-tightening may lead to a sudden increase in the leakage and with high-temperature fuel and water splashing, it can cause a severe burn to the operator skin.

8. Vibration and Loose Parts: Vibration is one of the main causes which increase the wear rate of moving parts. If loose bolts are found or heavy vibration is detected when the engine is running, stop the generator engine immediately and find the cause for rectification.

Incorrect Approach: It is not a common practice to check the tightness of the foundation bolts of the generator and its attached auxiliaries such as turbocharger etc. on ships. It has been found that many shipping company’s PMS do not include the foundation bolts and other bolts tightening checks in the routine.

9. Non-functional Alarms and Trips: During any point of time, if an alarm of the running generator is detected not to be working, then the generator needs to be stopped immediately as there is a possibility that other important alarms and trips are also not working. This can lead to major failure if an accident occurs in the generator.

Incorrect Approach: Ship crew on several vessels have a tendency to ignore alarms which they think are not important. It is many times observed by Port State Control (PSC) that generator alarms and trips are either not working or wrongly set. Such situations will do no good in saving the generator from disaster. Check all the alarms and trips on weekly basis.

10. Water in Oil: Water leaking in oil will decrease the load carrying capacity of the oil and leads to bearing damages. In such cases, the generator must be stopped if the water content is very high. Immediately find the leakage and renew/purify the sump oil before bringing the generator back in operation.

Incorrect Approach: Several cases have been found wherein the generator lube oil tests were not carried out regularly and the generator was allowed to run with water content in the oil. The effect of small amount of water is not immediately seen, but it will corrode and damage important parts of crankshaft and bearings in the long run.

The stopping of the generator is not limited to above points. There can be several other reasons which would require generators to be stopped immediately. However, it is the duty of the engineer to use his expertise and knowledge to avoid any kind of breakdown well ahead of time.

A wise engineer always think of the worst and hope for the best!

Over to you…

Do you know any important sign which suggests the ship’s generator should be immediately stopped?

Let’s know in the comments below.

10 Situations When Ship’s Generator Must be Stopped Immediately appeared first on Marine Insight - The Maritime Industry Guide

D’Carb or major overhauling of ship’s generator is an important and complicated task requiring professional skills, knowledge, and experience. Generators being the lifeline of the ships requires periodic maintenance which includes both routine and major overhauling procedures.

As an engineer onboard ships, you will be required to carry out the generator overhauling during routine maintenance or in case of an emergency situation. Thorough knowledge of the generator d’carb procedure is, therefore, a must for engineers of all levels working on ships.

Before and during the overhauling process, a variety of tests are performed on various tools and parts of the generator. Mentioned below are 10 important tests that are performed during major overhauling of the ship’s generator.

1. Hydraulic jack test: During overhauling, a variety of hydraulic jack tools are used for opening generator’s cylinder head, bottom end bolts, main bearing bolts etc.

In order to ensure a smooth d’carb process, proper testing of hydraulic jacks and pumps is done before using them for the overhauling procedure.

2. Cylinder head test: The cylinder heads onboard ships are overhauled and reused. Even the head supplied from shore is most of the time reconditioned. Hence it is important to test the heads for any leakage by means of pressure testing.

Pressure testing of the generator cylinder head is done by means of water and air.

3. Bearing cap test: The serration provided in the bearing housing holds the two caps against each other along with the con-rod bolts. Hence any damage to bolts will also result in damage to the bearing cap.

The bearing caps serrations are checked for cracks by using Die Penetrant test kit.

4. Con-Rod bolts test: The bottom cap holds the con-rod bearing by means of bottom end bolts which are subjected to reversal stresses. Crack test of Con-rod bolts is also to be done during every overhauling by using die penetrant test kit.

5. Connecting Rod Bend Test: The connecting rod is subjected to extreme pressures. When overhauling the generator, the con-rod is checked for straightness by inserting a brass rod in the oil hole of the con-rod having slightly less diameter than the oil bore. If the con-rod is slightly bent (which cannot be seen with the naked eye), the brass rod will not pass through the bore. 

6. Fuel Injector Test: Fuel injectors are generally re-used after overhauling. With timely use of the injector, its internal parts, which have very fine clearances, are subjected to wear and tear. Increase in clearance leads to dripping or other injection problem, eventually resulting in improper pressure injection.

Hence all the fuel injectors are pressure tested i.e. checking for correct opening pressure in the injector testing stand before using them in the generator.

7. Starting air valve testing: Like fuel injectors, air starting valves are also overhauled and reused. Hence to check the proper operation of the same, all starting air valves are tested by using service air for any leakage before installing into the cylinder head.

8.Relief valve test: The relief valve of the cylinder head is pressure tested to check proper functioning. It is an important part which prevents explosion of the head or damage to the combustion chamber because of overpressure. Pressure testing is carried out on a bench mounted test rig consisting of high-pressure air, pressure control valve, and calibrated gauges. The relief valve is bolted to the accumulator flange and the air pressure is increased until the valve lifts. Settings are done accordingly.

9.The current test: This is an important test which is done before trying out the generator with fuel after the completion of d’carb procedure. Once the d’carb is finished, the turning gear is engaged and with indicator cock open, the engine is turned. The current is continuously monitored. Any fluctuation or increase in the current value indicates obstruction or some problem in the rotating shaft.

10.Alarm and Trips test: The alarm and trips of the generator are electrical systems with wiring and contacts. To check their correct operation, testing of all the alarms and trips of the prime mover including lube oil trip, cooling water high-temperature trip, over speed trip etc. is done.

D’carb or major overhauling of a ship’s generator is a very tedious task for marine engineers on board. Following a step-by-step procedure backed by systematic planning is the base of a successful generator overhauling procedure.

Want to learn more about Ship generator overhauling procedure? Check out our ebook below:

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Any kind of emergency equipment or system provided onboard is an important lifeline for the ship and its crew when faced with an emergency situation. Emergency Generator is without doubt one of the most important equipment on board, which is responsible for preventing accidents and grounding during power failure while the ship is in heavy traffic, channels, rough weather or in manoeuvring.

The Emergency Generator on ship comes into play as back up source of power when the main generators fails to provide the necessary power to the engine room and other deck machinery systems.

Considering its high importance, the emergency generator is required to be tested regularly along with carrying out all important planned maintenance jobs as per schedule. This would not only ensure smooth running of the emergency generator but would also avoid breakdown when the ship is already facing a distress situation.

Following are some important maintenance jobs that need to be carried out in emergency generators on ships:

1. Change of Engine Sump Oil: It is important to check the oil level in the sump regularly. Since the emergency generator is kept on auto mode, which ensures the generator starts and comes on load automatically, it is necessary that before starting the engine for operation, oil level is checked on regularly basis. The condition of the oil will be known during this period and if the oil is having carbon or soot particles, change of complete oil system needs to be done. The running hours for changing of engine oil depends on the manufacturer, the engine make and the oil grade in use. Normally it is done between 250-500 hrs.

The oil changing period must be cut by half when the fuel used in generator is more than 0.5% to 1% sulfur.

2. Clean Air Cleaner: The combustion air for the engine is passed through an air filter, which can be of following types:

1. oil bath air cleaner

2. dry type air cleaner (cartridge or dust collector).

It is important to clean the air filter at correct intervals of time as delay will lead to clogging and less air going in the engine. This will reduce the efficiency of the engine and increase the thermal parameters. When using dry cartridge, ensure to replace them at intervals stated by the maker. Normal replacement schedule is one year or after 5-7 cleanings.

3. Check Water Separator: Some emergency generators are provided with water separator to prevent mixing of water with fuel. Check the level of water and make sure it is below the marked level and regularly drained off. This is to be done to avoid rust and corrosion of fuel line devices and to avoid incomplete combustion.

4. Check Electrolyte in the Battery: A battery is used in one of the starting methods of the emergency generator. The electrolyte level in the battery must be checked at regular intervals either by inserting a level stick or by checking the water level in the level tester cap (if provided). Use distilled water to make up for the low level.

5. Check Alarms and Shutdowns: All the safety devices and alarms fitted in the emergency generator must be checked and tested regularly. Generator with V-belts have additional alarm which will be sounded in the event of belt failure and operated by idler pulley.

6. Check V belt Tension: When V belt is fitted, inspect the same for cracks and damages. Renew the belt if damage/ cracking appearance is more. To check the belt tension, press the belt by thumb in midway of the pulleys and check the inward deflection in mm. It should not be more than 10-15 mm depending upon the make of the generator.

7. Clean Oil Filter Cartridge: The emergency generator is provided with various oil filters such as by pass filter, centrifuge filter, lube oil filter, fuel feed pump filter etc. These filters need to be cleaned or renewal of filter cartridge is to be carried out as per the maker’s instruction or oil condition.

8. Check Valve Clearance: The tappet clearance of the inlet and exhaust valve should be checked at running hours stated in the maintenance section of the generator’s manual. Also ensure the engine is cold before taking the tappet clearance.

Loss of emergency generators at times when they are needed the most can lead to unfortunate and disastrous incidents. Followed a proper planned maintenance system along with thorough regular checks is the key to ensure smooth running of emergency generators on board ships.

Over to you..

This is not an exhaustive list of important maintenance points. Are you aware of any other point that should be added to this list?

Let’s know in the comments below.

8 Important Points To Note For Maintenance Of Emergency Generators On Ship appeared first on Marine Insight - The Maritime Industry Guide

The shaft generator on a ship is an excellent example of a waste heat recovery system, which not only utilizes the waste energy from the engine but also supplies the additional work to the propeller shaft when the main engine is underperforming.

The shaft generator has two modes of operation:

1. Power Take Off (PTO): The additional energy generated in the main engine is taken off by the shaft generator to produce electricity as an alternative to the four-stroke gen-sets; hence this mode is called PTO or Shaft generator mode.

*PTO can improve ship EEDI figures

2. Power Take In (PTI): Power Take in (PTI) mode provides propulsion power to the shaft which boosts the main engine with temporary extra power. It can also be used as an emergency backup machinery to propel the ship to the nearest shore if the main engine goes out of operation, thereby increasing the redundancy factor. This mode is also known as shaft motor mode.

*PTI can deteriorate the EEDI figures if used for increasing the ship’s speed

Operation:

Power Management System (PMS) is installed in the ship’s engine room to look after the safety and operation of the power generating machinery, which includes auxiliary generator, turbine generator, and shaft generator.

The Shaft Generator – Motor circuit breaker is usually closed, if not, an operator can close the circuit breaker via the PMS panel. This command is released if sufficient apparent power is available. The two modes explained above is controlled by PMS of the ship.

Shaft Motor Mode: 

The shaft motor mode can be further classified into:

Run up assistance (override function):

This mode can be selected in the PMS panel and once selected, it will override the currently active mode. The preconditions to enable this mode are:

• Thermal run-up main engine (load program is active)
• The auxiliary or/and turbine generator are already connected to the busbar in automatic mode

Under this mode, the shaft motor uses power from the auxiliary and turbine generators and then supplies the additional propulsion power to the main engine during acceleration from maneuvering speed to cruising speed, resulting in the reduction of thermal stress.

If the turbine generator and the connected auxiliary engine produces more power than required, the PMS will reduce the power of the Diesel(s) and stop the excess running auxiliary engine to save fuel.

ELS (Economical Load Sharing):

This mode is useful when turbine generator is available in the engine room. To run this mode, following precondition to be fulfilled:

• The turbine generator or Diesel generator is already connected to the bus bar in automatic mode

From the available steam and exhaust heat of the main engine, the turbine generator will produce as much power as possible. The excess power (power left after supplying to ships machinery and cargo load) will be used to power the shaft motor, which will then assist in the propulsion. Consequently, the load on the main engine will reduce and it will consume less fuel oil.

This is possible under normal sea running conditions when the turbine generator produces more power than required for the ship network and reefer container supply. In case of raised consumption or lower power production, the PMS will reduce the load of the shaft motor. If the load is nearly 0 KW, the PMS will change the shaft motor to the shaft generator.

Automatic booster:

To run this mode, following precondition to be fulfilled:

• The turbine generator or Diesel generator is already connected to the bus bar in automatic mode

In this mode, the shaft motor supports the main engine in case of load limitation to achieve the desired speed.

The automatic booster continuously monitors the shaft generator power, and if it is 0KW, it will stop the shaft generator, and this mode will change it over to the shaft motor mode and increase the load of the shaft motor with other diesel generators in service.

Depending on the consumption in the network the shaft motor can be kept in service or the shaft motor will have to be changed over to the shaft generator.

If the shaft motor can be kept in service, the auxiliary engines will be de-loaded to their minimum load. The AE’s will be maintained in service until the HP dumped steam has been able to substitute the shaft generator power for at least 15 minutes.

Manual booster:

To run this mode, following precondition to be fulfilled:

• The turbine generator or Diesel generator is already connected to the bus bar in automatic mode

The manual booster function is used to boost ships speed by assisting the propulsion engine in a situation where the stress reduction in the main engine is necessary.

Example of such situation is the Minor main engine alarm, where the crew will de-load the engine and closely track the engine trends.

The manual booster function will boost as much as possible with the currently connected auxiliary engine and turbine generators but is limited by an operator setting.

This mode will not automatically start additional Diesel engines.

Limitations of Shaft Motor:

The shaft motor will be limited in situations wherein sufficient power is not available. The PMS will activate the limitation, usually, if the Diesel generator achieves 95 % of the available power (This value is above the ‘standby’ limit and below the ‘trip of unessential consumers’ limit) or if the turbine generator sends the “full load” signal.

The Shaft Motor converter controller itself limits the load of the shaft motor automatically if the bus bar frequency falls below 58.0 Hz. This limitation is independent of the PMS.

Shaft Generator Mode:

To important precondition for starting the shaft generator is:

The SCM is ready to start or is already connected to the bus bar.

*Synchronous Condensing Motor provides necessary reactive power which cannot be supplied by a DC circuit. It also takes care of the voltage regulation of the system.

SCM operating sequence:

• When a shaft generator is started, the PMS will 1st start, synchronize and connect the SCM to the bus bar.
• Once the shaft generator is stopped, the PMS will send a stop signal to the SCM (if the turbine generator is not connected to the bus bar).

Note: If the SCM is not available, a start of the shaft generator will be blocked, but the starting the shaft motor will be possible.

In some systems, new technology – “pulse width modulated converter system” is used which supplies effective power and reactive power to load on ships without the need of asynchronous condenser.

In this mode, the shaft generator will run as a normal generator on the bus bar providing additional power to the main switchboard of the ship.

The normal PMS settings for the power production of the shaft generator compared to a turbine and auxiliary generators are:

1. Turbine generator and Shaft generator in parallel:

If the shaft generator runs in parallel with the turbine generator, the turbine generator will produce as much power as possible, and the shaft generator will provide the remaining power.

2. Shaft generator and auxiliary generator in parallel.

If the shaft generator runs in parallel with a Diesel generator, the shaft generator will produce as much power as possible, and the diesel generator will produce the remaining power.

If the reserve power of the shaft generator falls to 10% of the nominal power, the PMS starts, synchronizes and connects the first standby diesel generator to the bus bar. If the power of the auxiliary generator achieves its minimum load, the AE will be kept in service until the shaft generator has been able to substitute the AE power for 15 minutes. The PMS will than de-load, disconnect and stop the auxiliary engine.

Special use in shuttle tanker:

In shuttle tanker, the shaft generator can be used to drive electrical cargo pumps for enabling the cargo operation by running the main engine. This is only possible with a plant having a controllable pitch propeller. The CPP is set to 0 RPM, and the main engine is run to generate electricity for cargo pump supplied via shaft generator. A flexible coupling is provided between the PTO and the intermediate shaft with a built-in torsion limiting device. In case of breakage of this flexible elements, the device will transmit the torque by the help of steel parts until the safety system has shut down the engine.

Limitations:

The maximum available power of the shaft generator / – motor will depend on the main engine rpm. Below the ME minimum rpm limit of ME (Say 40 rpm) the Shaft generator will be blocked by the PMS.

During rough weather, as the propeller comes out of the water the speed variations will increase and may reach a level where shaft generator operation is not possible and, accordingly, the electricity production must be shifted to the auxiliary engines.

By installing a shaft generator/motor on a vessel, it can run much more efficiently and take into consideration all conditions that place fluctuating demands on their loads. Use of this waste recovery machine leads to high-efficiency performance and significantly lowers fuel consumption, allowing ship owners to gain higher profit margins from their businesses.

Do you know any other important points that can be added to the article?

Let’s know in the comments below.

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. 

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Understanding Different Operational Modes Of Shaft Generator On Ships appeared first on Marine Insight - The Maritime Industry Guide

Emergency generator on ship provides power in case the main generators of the ship fails and creates a “dead or blackout condition”. According to general requirement, at least two modes of starting an emergency generator should be available. The two modes should be – battery start and hydraulic or pneumatic start.

The Port state control (PSC) might detain a ship or provide some time to correct any kind of deficiency found if the second mode of starting is not operating.

Testing of Emergency Generator

The testing of ship’s emergency generator is done every week (as part of weekly checks) by running it unloaded to check if it starts on battery mode. The hydraulic start is done every month to ensure that it is working fine. Also every month automatic start of generator is also done to check its automatic operation and to see whether it comes on load.

Procedure for Battery Start

1. Go to the emergency generator room and find the panel for emergency generator.
2. Put the switch on the test mode from automatic mode. The generator will start automatically but will not come on load.
3. Check voltage and frequency in the meter.
4. Keep the generator running for 10-15 min and check the exhaust temp and other parameters.
5. Check the sump level.
6. For stopping the generator, put the switch in manual and then stop the generator.

Procedure for Hydraulic Start

1. Out the switch in manual mode as stated above and check the pressure gauge for sufficient oil pressure.
2. Open the valve from accumulator to generator.
3. Push the spring loaded valve and the generator should start.
4. Check voltage and frequency.
5. Keep the generator running for 10-15 min and check the exhaust temp and other parameters.
6. Check the sump level
7. For stopping, use the manual stop button from the panel.
8. After stopping the generator, pressurize the hydraulic accumulator to desired pressure.
9. Close the valve from accumulator to generator.

Procedure for Automatic Start

1. For automatic start, we know that there is a breaker which connects Emergency Switch Board (ESB) and Main Switch Board (MSB); and there is also an interlock provided due to which the emergency generator and Main power of the ship cannot be supplied together.
2. Therefore, we simulate by opening the breaker from the tie line, which can be done from the MSB or the ESB panel.
3. After opening the breaker, the emergency generator starts automatically with the help of batteries and will supply essential power to machinery and pumps connected to ESB.
4. For stopping the generator, the breaker is closed again and due to the interlock the generator becomes off load.
5. Now again put the switch to manual mode to stop the generator.
6. Press stop and the generator will stop.

You may also like to read – Free Sample:Generator Running Tests

Ways of starting and testing emergency generator appeared first on Marine Insight - The Maritime Industry Guide

The power generated by the piston in the combustion chamber of marine engine is transferred to the crankshaft using the connecting rod. While transferring this tremendous power, the connecting rod itself is subjected to different stresses, which makes is vulnerable to damage. For this reason connecting rod bolts are used to join the connecting rod and con-rod bearing cover under the tremendous stresses generated by the running engine.

The most common type of connecting rod that is used in the ship’s auxiliary engine is oblique or cross-cut connecting rod which is made of two parts.

The connecting rod of the engine must be inspected at regular intervals of time to ensure there is no defect or problem to avoid any future accidents/emergency. It’s the knowledge and skills of the engineer that decides whether to use the same connecting rod or to renew it with the spare one.

Following points must be considered when checking the connecting rod for re-use or replacement:

1. Check the ovality of the connecting rod: Check the ovality of the connecting rod by tightening both parts at its rated torque. Inside micrometer is used to determine the correct and current ovality of the connecting rod. If the ovality is out of limits, the connecting rod is not to be reused.

2. Check connecting rod for fretting and corrosion: Connecting rod to be checked for fretting and corrosion. If fretting is small, it can be removed by using oilstone. Never use grinder or scrapper for this purpose. Con-rod with severe fretting and racks must be discarded.

3. If connecting rod with fretting is to be used, check for cracks: Minute fretting can be tolerated over the connecting for reuse only if the surface does not have any cracks. If the fretting is in small area and oil stone is used to treat the same, the complete area must be checked again by using magnaflux which detects small hairline cracks which are not visible to the naked human eye.

4. Check cracks between connecting rod and bearing cover: The serration and bore between connecting rod and bearing cover to be checked for cracks by using die penetrating crack detection test. Rod to be used only when there are no cracks detected. If there are small cracks in the connecting rod bearing cap serration, renew it with new spare one.

5. Renew connecting rod and connecting rod bearing cover together: Connecting rod and connecting rod bearing cover to be renewed as a whole. Never renew single part of the connecting- rod in case of damage as the serrations are machined in pair to locate the two halves relative to one another.

6. Re-machining of serrations should not be done: Re-machining of serrations of connecting rod /bearing cap or bore should not be done even if there is minute damage or indentation.

7. Bearing shell with fretting at its back should not be used: Bearing shell with fretting at it’s back side must not be used with connecting rod and it is to be renewed in set.

8. Ensure bolts and bearings are of same type during replacement: If the connecting rod is replaced, it should be of same type and same con-rod bolts and bearings to be used. Ensure to read the older generator data to confirm the bearing size (undersize or oversize) to be fitted while renewing the shell.

9. Replace Connecting Rod Bolts in Sets: Connecting rod bolts to be used and replaced in sets. If the connecting rod is renewed with the spare one, the con-rod bolts from the old con-rod must not be used with the new spare connecting rod.

10. Correct sequence and tightening torque: Once it is decided to reuse or replace the connecting rod, the engineer office must ensure that he knows the correct assembling sequence (front/ back side, pair of con-rod and bearing cap etc. ) and rated tightening torque is applied on the con-rod bolt with step- by-step tightening procedure as listed in the manual.

The assessment of connecting rod for reusing/ discarding is a critical decision to make for the ship’s engineer officer. A slight mistake in making the correct choice may lead to major generator damages and sometimes even causality.

The above mentioned are some of the important basic checks which should be performed by the engineer to upkeep the generator’s long life and efficient performance.

Do you know any other important point that can be added to this list?

Let’s know in the comments below.

What’s The Criteria For Reuse or Replacement of Auxiliary Engine Connecting Rod On Ships? appeared first on Marine Insight - The Maritime Industry Guide

Maintaining continuous power on the ship is one of the most important tasks while sailing. However, sometimes accidents are inevitable and due to some reason such as a breakdown of machinery, technical snag etc. there can be a power failure on the ship.

During such conditions, emergency equipment like life boat, navigation lights etc. should be in operating conditions so that they can be used in case of emergencies.  As we all know that a ship is built underclass regulations and all the necessary regulation described by SOLAS and IMO have to be followed during the construction of the ship.

In case of blackout there should be an alternate source of power available and which should come on load automatically. The alternate source of power is taken from batteries and emergency generators to provide power to critical equipment. As batteries cannot provide power for a longer period of time, emergency generators are preferred.

Understanding Emergency Power System

As per SOLAS regulation the emergency power equipment should come on load within 45 seconds of the power failure. When the power failure takes place the emergency generator is normally started by a small electric motor which cranks the engine for starting. This motor gets power from the battery which is being charged by emergency switchboard.  Also in case the equipment or emergency generator is unable to start due to any reason, there should be an alternate method or manual starting available in hand. As per Solas regulation, the secondary means of starting should be able to provide additional three starts within 30 minutes.

One of the most common methods for starting emergency generator is hydraulic starting. Options other than hydraulic start are:

1) By compressed air.

2) Inertia starters.

3) Hand cranking

Construction and Working Principle

Hydraulic system for starting works on the principle of hydraulic and pneumatic, in which, the energy is first stored and then supplied or released for the starting of the engine.

The main components of this system are:

1) Feed tank and hand pump

The feed tank is provided with hydraulic oil which is pumped by the hand pump to the accumulator which helps in starting the engine.

2) Hydraulic Accumulator

This is the most important component of the system. It is the heart of the system where the energy is stored. It consists of a cylinder in which there is a leakproof sliding piston. Above this piston, the cylinder is pre-charged with the nitrogen gas to about a pressure of 200 bars. The oil is pressed against this piston and necessary pressure of oil is stored in the accumulator.

3) Pressure Gauge

This is to check the pressure in the accumulator.

4) Relay valve lever

The operation of this lever will release the energy stored in the accumulator to the starter unit.

5) Starter unit and engine dog

The starter unit is attached to the free end of the engine with the help of a bracket and the engine dog is attached to the engine crankshaft with the help of a suitable adapter. This starter unit consists of two opposed cylinders with rack and pinion arrangement. The pinion arrangement has teeth on one end which drives the dog having the corresponding teeth. Two helical grooves are formed inside the periphery of the pinion which is engaged by spring loaded balls inside the starter housing which helps in engaging and disengaging by the axial movement. The positive engagement is maintained by the helical tooth form of the pinion and racks.

How to Operate the Hydraulic Starter?

1) Check whether all the valves for fuel, cooling water etc. are open to the generator.

2) Check the level of the feed tank. Fill it if necessary. Please see that if the level in the gauge glass is low and the pressure in the accumulator is ok as per manufacturer recommendation then do not fill the tank as the oil will return from the starter after starting.

3) Check the pressure in the accumulator. Raise pressure if required. Pressurize the accumulator as per OEM recommendations.

4) Operate the relay valve lever. The relay valve lever operates in two stages. Move the relay valve to an angle of 45 degrees, at this position the resistance is felt. In this stage a small bleed is given to the starter causing a slow rotation, engaging the dog. When the dog gets engaged to operate the lever fully. This releases the pressure in the starter and engine starts. The sudden jerk of relay lever is avoided so as to prevent damage to the gears and the clutching arrangement.

5) When the engine starts turning, release the lever and the lever goes back to normal position. The oil used for starting the engines comes back to the feed tank after starting.

6) Check the pressure in the accumulator. It should be enough for two additional starts.

7) Raise the pressure again for the next emergency.

If you liked this article, you may also like Procedure for starting emergency steering system.

Hydraulic Starting of Emergency Generator appeared first on Marine Insight - The Maritime Industry Guide

A ship cannot remain “Live” without a Generator – the lifeline and power production plant of the vessel. A generator on ship is a combination of two separate systems – an alternator and a prime mover whose capacity depends upon the number of machinery or power consuming items fitted on the ship.

What is Alternator?

An alternator is an electro-mechanical device comprising of stator, rotor winding and an external exciter for supplying excitation voltage. Alternator generates electricity when coupled with a prime mover.

Alternator on a ship is exposed to harsh weather and sea conditions, due to which, its capacity and efficiency tends to reduce. It is very important to have proper maintenance on the alternator part of the generator as per planned maintenance or as and when required.

Following Points are to be considered while Carrying Out Maintenance on Alternators:

Before starting any maintenance work on the alternator, all safety precaution should be taken and the alternator should be shut and locked down. Also, post notice and ply cards on relevant places and alternator heater to be isolated.

• Clean the alternator ventilation passage and air filter.

• Check the Insulation resistance of stator and rotor winding.

• Air gap between stator and rotor to be checked and maintained between 1.5 to 2 mm.

• Slip rings to be checked for even wear down to be renewed if required.

• Carbon brushes to be clean and checked for free movement.

• The brush contacting pressure to be checked by spring balance.

• Automatic Voltage Regulator to be checked and cleaned off oil and dust.

• The lube oil level of pedestal bearing to be maintained and renewed as per planned maintenance.

• A vacuum cleaner can be used to remove dust accumulated in the inner parts of alternator.

• The terminal box cover gasket to be checked for proper oil and water tightness.

• All the connection in the terminal box to be tightened properly.

• Cable gland to be checked for integrity.

• Forced Ventilation around alternator must be maintained all the time.

• Check heater for proper operation.

• The foundation bolts of the alternator to be checked for tightness.

After maintenance is performed, a no load test should be carried out and general condition such as noise, temperature, voltage generated etc. of the alternator should be observed and noted.

Important Points to Consider While Carrying out Alternator Maintenance of Ship’s Generator appeared first on Marine Insight - The Maritime Industry Guide

Power generation is a continuous requirement on board ships. A blackout situation even for a few minutes can lead to devastating results such as grounding, collision etc., resulting in heavy losses and danger to the ship and its crew.

A ship is equipped with multiple generators/ auxiliary engines to supply continuous power at all times. These power generating units are watched over and maintained by ship engineers.

A sensible ship engineer will try to run a minimum number of generators at any given period of time and look for maximum load, which not only ensures goodwill for the auxiliary engines but also reduces overall fuel consumption and harmful emissions. This can happen when the auxiliary engine rated output is achieved without any deviation in the engine parameters (temperature, pressure etc.).

If the engine performance is deteriorating, it will result in reduced output with high exhaust temperature and low peak pressure. The reduced output of one generator will require another generator to run in parallel and compensate the power demand.

Ship engineers must know the probable reasons which can lead to a reduced power output of auxiliary engines.

Following are 20 possible causes, which will lead to reduced power output and performance of an auxiliary engine on board ship:

1. Fuel oil pressure too low: The fuel oil pressure is lower than the requirement, which can be due to faulty fuel oil attached pump or the fuel oil viscosity is very low

2. Type of Fuel Burned: The fuel oil pressure will also drop when the fuel grade is changed from HFO to MDO/ MGO/LSFO. This will lead to a decrease in engine performance

3. Fuel leakage: If the fuel pump parts i.e plunger and barrels are worn out, the fuel will leak out and the fuel pressure will drop at the discharge point

4. Fuel Temperature: If the fuel temperature is inadmissibly high (>60 deg C), the fuel viscosity will reduce and it will affect the fuel pressure

5. Firing Pressure Difference: If there is a high difference firing pressure in between individual cylinders, it will lead to a reduction in the overall output of the engine

6. Blocked Filter: Blocked or dirty line filters in the fuel oil system will reduce the oil pressure and hence the performance

7. Wrong Valve Clearance: The clearance between the intake/ exhaust valve and its guides is of extreme importance. If the clearance is more than required, the combustion mixture will leak out from this gap and reduce the engine performance

8. Damaged Exhaust Valve: A damaged exhaust valve or seat will not seal properly causing blow-by of exhaust gasses on combustion. This will increase the exhaust temperature and reduce engine output

9. High Exhaust Back Pressure: If there is a flaw in the exhaust piping installation or the silencer is fouled, it will lead to high exhaust gas pressure and an increase in exhaust temperature of all units

10. Contaminated Passages: A contaminated exhaust manifold will lead to hindrance in the exhaust gas flow and increase the exhaust temperature

11. Insufficient Fresh Air Supply: Correct amount of fresh air supply is a must for efficient combustion, if there is a reduction in the scavenge air supply, the combustion will be incomplete, which will reduce the engine output

12. High Suction Air Temperature to T/C: When a ship plies in hotter temperature regions (For e.g near the equator or Gulf regions in summers) the atmospheric air sucked by T/C compressor is already at a higher temperature. If this air is not cooled properly, it will decrease the performance of the engine

13. Charge Air Pressure Too Low: If the scavenge air pressure is low, the amount of air required for combustion to each the cylinder will not be sufficient, which will lead to incomplete combustion

14. Wrong Charge Air temperature: If the cooler controller is set at a higher temperature, the temperature of the output air supplied to the engine will be higher, which is not good for engine performance. Similarly, if the setting is on the lower side, the resulting combustion will not be efficient

15. Charge Air Cooler Contaminated: A contaminated and dirty charge air cooler will not allow seawater to cool the air properly, leading to an increase in exhaust temperature

16. Air Cooler S.W Temp High: If the seawater temperature is on the higher side, the air-cooled by it in the air cooler will be warmer than normal which will lead to high exhaust temperature

17. Air Cooler S.W Bypass Open: The air coolers provided with S.W bypass valve controls the cooling medium i.e seawater. If the bypass is open more than required, then the air supplied to the engine will have a higher temperature

18. Blower, Turbine or Nozzle Ring Worn/ damage: Fouled or damaged part of turbocharger will lead to either problem in the passage of exhaust gas or less amount of fresh air supply. These will lead to a sudden reduction in the output of the engine

19. Scavenge Air Leakage: Leaking scavenge air from the inlet pipe to the cylinder will result in less supply of air and incomplete combustion

20. Wrong Tappet Clearance Setting: Wrong tappet clearance will allow inlet/ exhaust valves to open more or less than required. This will result in either inappropriate combustion or the combustion mixture drawing out of the chamber at an earlier stage

Over to you..

Do you know any other important point that can be added to this list?

Let’s know in the comments below.

20 Possible Causes for Reduction in Ship’s Auxiliary Engine Performance appeared first on Marine Insight - The Maritime Industry Guide

On ships, there’re a separate set of systems provided both on deck and engine room for emergency situations. Some of the most important emergency machinery and systems on board ships are – Emergency compressor, Emergency bilge suction, Emergency fire pump, Lifeboat, and Emergency generator.

As per the SOLAS requirements, all emergency equipment/systems must be tested frequently (general practice on a ship- weekly) to ensure they run smoothly when really needed, especially in an emergency situation.

Out of the all the systems, the emergency generator is one of the most frequently used machinery as a blackout situation can occur anytime on a ship.

Therefore, it is very important not only for the engineer officer but also for the deck officer/crew to know the ways of starting and testing the emergency generator, as per the regulations laid down under SOLAS.

Important requirements for the prime mover of the emergency generator are:

• The emergency electrical power providing generator shall be driven by a suitable prime mover having independent auxiliary systems, which may consist of fuel, ventilation, lubrication, cooling etc.
• The fuel used in the emergency generator prime mover must have a flash point of > 43° C
• The prime mover of the emergency generator shall be started automatically once the main source of electrical power supply fails
• If the emergency generator does not start or does not take the load of the emergency switchboard connections, an indication shall be given in the engine room or at a manned control station

Related Read: How The Power Requirement Of A Ship Is Estimated?

Apart from complying with the SOLAS Ch II Reg 43, the important job of ship’s engineers is to maintain the emergency generator in top notch condition.

Following are the important points that should be remembered when handling emergency generator:

1. Anti-freezing compounds are added to the emergency generators to ensure it will start even at very low temperatures (-ve temperature). If using fully formulated anti-freeze compound, mix it with good quality water in a ratio of 1:1 or as stated by the manufacturer. If the fully formulated antifreeze compound concentration is kept higher than required, the cooling system may silica gel formation issue.

Related Read: What to Do When the Ship is Moving towards Sub Zero Temperature Area?

2. When mixing anti-freeze solution to the system, avoid pouring it alone in the radiator. It should always be mixed in the prescribed ratio with water before pouring into the cooling water system of the generator. This is because the potential of the ant-freeze liquid to remove heat is not as good as that of water and putting the anti-freeze compound alone in the cooling system may contribute to overheated condition before the liquids are completely mixed together.

3. Coolant is used in the engine cooling water system to control the overheating of the generator. They are added mixing with water. Never add coolant mixture at a low temperature to a hot engine. This may lead to damage to the engine casting. Always stop the engine and let it cool down before adding the coolant mixture.

Related Read: 8 Important Points To Note For Maintenance Of Emergency Generators On Ship

4. When adding the coolant mixture after a major overhaul or draining the cooling system, ensure to open the engine and aftercooler vent while filling the coolant to the system to allow air to escape and avoiding airlock

5. It is not a good practice to test the cooling water used in the emergency generator after a long interval of time. Ensure to test the cooling water quality every week and maintain it at a pH of 8 – 10.5 to avoid excessive scaling problem (if calcium and magnesium levels are more) or corrosion problem (if chloride and sulphate levels are more)

Related Read: 10 Important Tests for Major Overhauling of Ship’s Generator

6. Unlike auxiliary engine generator, the emergency generator should not be idled for a long period. Long idle timing (more than 10 minutes) will affect the fuel burning as combustion chamber temperature is very low. This will cause carbon clogging of the injector holes and sticking of the valve. The best idle time is considered to be 3-5 minutes for the emergency generator.

7. If the engine is idled for a long and the coolant temperature becomes too low (50-60 deg C), the fuel in the combustion chamber will remain unburnt and will wash the lubrication between piston and liner, causing damage to the moving parts.

Related Read: 10 Extremely Important Checks Before Starting Marine Engines

8. The most common problem found in the belts used in the engine to drive the water pump are cracks. Transverse cracks (cracks generated across the belt width) on the surface of the belt are acceptable within the prescribed limit. When the transverse crack is seen intersecting with longitudinal cracks, it is advisable to immediately change the belts.

9. The most common problem found in the radiator fan is the loosening of the screw, which connects blades to the rotor. Never stand in front of the fan (which is set up outside the emergency generated room, to open atmosphere) as a loose screw or broken blade may lead to a personal injury. Never try to rotate the engine using fan blades to avoid injury or breakage of blades itself. Always stop and isolate the engine before tightening the screw on the blade or doing any other maintenance on the fan.

Related Read: 10 Extremely Dangerous Engine Room Accidents On Ships

10. It is always advisable to fill the lube oil filter with lube oil (or fuel filter with fuel oil) before fitting the same to the emergency generator to avoid dry start-up.

11. If an emergency generator provided with compressed air start system, ensure the compressed air unit does not have any lube oil carryover. Prolong carriage of lube oil will form varnish and carbon deposits around the piston of the compressed air chamber and it will not allow it to seal and generate high pressure required for the starting.

Related Read: 8 Things Marine Engineers Must Know About Starting Air System On Ship

12. After a major overhaul, it is important to vent the air trapped in the high-pressure fuel line (of injectors). Each high-pressure fuel line to be vented separately by slightly opening the vent screw provided in the fuel line and by cranking the engine. If the engine needs to be started, ensure not to engage the starter for more than 30 seconds and provide a rest interval of 2 minutes before venting the next injector.

13. Avoid running with oil mixture atmosphere to prevent overspeeding of the generator or explosion of the internal parts. Such atmosphere is possible while loading hazardous cargo on the ship which can go inside the emergency generator through its air intake. Never mix gasoline or alcohol as it can cause an explosion.

Related Read: 10 Situations When Ship’s Generator Must be Stopped Immediately

14. After a major overhauling of the engine or when the Top Dead Centre (TDC) of the unit has to be marked, a locating pin is provided in most of the emergency generators which will sit in the hole of the gear drive attached to the camshaft, ensuring the first unit is in TDC. Once the TDC is located, ensure to remove the pin, else starting the generator will damage the pin and the locating hole

15. When the ship is plying in a low-temperature region for a longer duration, there is no provision to keep the emergency generator warm when it is not operational. It is advisable to use synthetic lubricating oil with low-temperature properties with low sulphated ash limit

Related Read: Important Lube Oil Properties to be Considered While Choosing Marine Lube Oil 

The make and capacity of the emergency generator vary on ships and the engineer must know the operational and maintenance procedure of the machine thoroughly. The above tips broadly remain the same for all emergency generator models fitted on commercial ships and in case of doubt or assistance, it is always advisable to contact the makers for recommendations.

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight.

15 Pro Tips To Handle Emergency Generator On Ships appeared first on Marine Insight - The Maritime Industry Guide

An emergency steering system, as the name suggests, is a system which is used during the failure of the main steering system of the ship. The article explains as to what exactly is the steering system and what the procedure for starting the emergency steering system is.

What is Emergency steering?

A ship consists of electromechanical steering gear unit which steers the vessel from one port to other. Normally steering gear unit is 2 or 4 ram electro-hydraulically operated unit with two or more hydraulic motor for the ram movement.

A situation can occur in which the remote control operation may fail to work and their can be a sudden loss of steering control from the bridge. This can be due to sudden power failure, any electrical fault in the system or the control system which includes faulty tele-motor or servo motor which is used for transferring the signal from bridge to the steering unit.

To have control the steering of the ship at such emergency situation with manual measure from within the steering gear room, an emergency steering system is used.

Procedure for Emergency steering Operation

The following points should be followed for emergency steering operation.

• The procedure and diagram for operating emergency steering should be displayed in steering gear room and bridge.
• Even in emergency situation we cannot turn the massive rudder by hand or any other means, and that’s why a hydraulic motor is given a supply from the emergency generator directly through emergency switch board (SOLAS regulation). It should also be displayed in the steering room.
• Ensure a clear communication for emergency operation via VHF or ships telephone system.
• Normally a switch is given in the power supply panel of steering gear for tele motor; switch off the supply from the panel.
• Change the mode of operation by selecting the switch for the motor which is supplied emergency power.
• There is a safety pin at the manual operation helms wheel so that during normal operation the manual operation always remains in cut-off mode. Remove that pin.
• A helms wheel is provided which controls the flow of oil to the rams with a rudder angle indicator. Wheel can be turned clockwise or anti clockwise for going port or starboard or vice versa.
• If there is a power failure, through sound power telephone receive orders from the bridge for the rudder angle. As soon as you get the orders, turn the wheel and check the rudder angle indicator.

A routine check should always be done for proper working of manual emergency system and steering gear system. An emergency steering drill should be carried out every month (prescribed duration – 3 months) in the steering gear room with proper communication with bridge to train all the ship’s staff for proper operation of the system so that in emergency situation ships control can be regained as soon as possible, avoiding collision or grounding.

Procedure for Starting Emergency Steering System appeared first on Marine Insight - The Maritime Industry Guide

Synchronization of Generators is the process of matching parameters such as voltage, frequency, phase angle, phase sequence, and waveform of an alternator (generator) or other sources with a healthy or working power system. A generator cannot supply electricity to an electric power system unless its voltage, frequency, and other parameters are precisely matched to the network. The exciter current and the generator’s engine speed are controlled to achieve synchronization.

 Synchronization is primarily needed when two or more alternators work together to supply power to the load. Electrical loads are very inconsistent and they vary with time (depending on the load) and so it is necessary to interconnect the alternators operating in parallel to supply larger loads. 

It ensures that the various parameters of one alternator ( or generator) resonate with another alternator or with the bus bar. The process of synchronization is also known as Paralleling of Alternators or Generators.  

The synchronizing of the generator is done with the help of a synchroscope or with the three-bulb method in case of an emergency. It is of utmost importance that before paralleling the generators, the frequency and voltage of the generators need to be matched. In this article, we will describe the method for synchronizing generators on a ship.

Structure of Synchronous Generator

The synchronous generator comprises a rotor and a stator similar to a standard generator. The rotor consists of an electromagnet that rotates in the stator. The stator comprises windings that induce a 3- phase voltage and it consists of three stationary coils known as a stator, armature, or phase coils.  Magnetization is also crucial for the stator windings because in absence of magnetic fields there are no forces to create currents.

To calculate the synchronous speed of the generator we use the formula-

Ns=(120 * f) / P

Where: 

Ns = Synchronous speed, rpm 

f = Frequency, Hz 

P = Number of poles 

120 is a constant for the time (seconds/minutes) and pole pairs, to get the speed in rpm.

Requirements for Synchronization or Paralleling of Generators

There are certain conditions that have to be met for the successful paralleling of generators. The underlying conditions must be met in order to synchronize a generator to the grid or with other generators. 

Phase Sequence

The phase sequence of the three stages of the alternator connected to the power system bus must be identical to the phase sequence of the three phases of the bus bar (or electric grid). This issue usually arises during the initial installation or during routine maintenance.

Voltage Magnitude

The incoming alternator’s RMS voltage should be the same as the bus bar or electric grid’s RMS voltage. There will be a lot of reactive power flowing from the generator into the grid if the incoming alternator voltage is higher than the bus bar voltage.

The generator absorbs the high reactive power from the bus bar if the input alternator voltage is lower than the bus bar voltage.

Frequency

The frequency of the incoming generator must match the bus bar’s frequency. Inadequate frequency matching causes the prime mover to accelerate and decelerate rapidly, increasing the transient torque.

Phase Angle

There should be no phase angle between the incoming generator voltage and the voltage of the bus bar. By comparing the occurrence of zero-crossing or peaks in the voltage waveforms, this can be seen.

 Methods to Synchronize Generators on a Ship

There are two methods to synchronize generators on a ship – one is the normal and the other is the emergency method.

1. Synchroscope method

A synchroscope is used to check the consequent frequency difference between the generators and the grids’ voltages.

1. The synchroscope consists of a small motor with coils on the two poles connected across two phases. Let’s say it is connected in red and yellow phases of the incoming machine and armature windings supplied from red and yellow phases from the switchboard bus bars.
2. The bus bar circuit consists of inductance and resistance connected in parallel.
3. The inductor circuit has the delaying current effect by 90 degrees relative to the current in resistance.
4. These dual currents are fed into the synchroscope with the help of slip rings to the armature windings which produces a rotating magnetic field.
5. The polarity of the poles will change alternatively in the north/south direction with changes in the red and yellow phases of the incoming machine.
6.  The rotating field will react with the poles by turning the rotor either in a clockwise or anticlockwise direction.
7. If the rotor is moving in a clockwise direction this means that the incoming machine is running faster than the bus bar and slower when running in an anticlockwise direction.
8. Generally, it is preferred to adjust the alternator speed slightly higher, which will move the pointer on the synchroscope in a clockwise direction.
9. The breaker is closed just before the pointer reaches the 12’o’clock position, at which the incoming machine is in phase with the bus bar. This is because it takes a few more milliseconds for the contactor to pull in, so one starts the operation a little early.
10. When the synchroscope is approaching 12 o’clock the “slip” between the sine waves is approaching minimum at 12 o’clock and the voltage differential between the phases is also minimal at 12 o’clock. By closing the breaker at 11 o’clock, we are achieving closing close to 12 o’clock.

Pros and cons of the Synchroscope method

• It is more accurate than lamps.
• The element of a personal judgment of the operator regarding the exact instant of synchronizing is nearly eliminated.
• It is costlier than lamps.
• It does not indicate the phase sequence.

2. Emergency synchronizing lamps or three bulb method

This method is generally used when there is a failure of the synchroscope. In case of failure, a standby method should be available to synchronize the alternator, and thus the emergency lamp method is used.

Three lamps should be connected between three phases of the bus bar and the incoming generator should be connected.

1. The lamps are connected only in this manner because if they are connected across, the same phase lamps will go on and off together when the incoming machine is out of phase with the switchboard.
2. In this method, the two lamps will be bright and one lamp will be dark when the incoming machine is coming in phase with the bus bar.
3. The movement of these bright and dark lamps indicates whether the incoming machine is running faster or slower.
4. For e.g. there is a moment when lamp A will be dark and lamps B & C will be bright, similarly, there will be instances when B is dark and others are bright and C is dark and the other two are bright. This example indicates that the machine is running fast and the  movement of the lamps from dark and bright gives a clockwise movement
5. Clockwise movement indicates fast and anti-clockwise direction indicates slow running of the incoming generator.

The ON and OFF rate of these lamps is determined by the frequency difference between alternator-2 voltage and bus bar voltage. As a result, the flickering rate must be lowered to match the frequency. This is accomplished by regulating the alternator’s speed via the prime mover control.

The bulbs will turn dark once all of these parameters have been established, and the synchronizing switch can then be closed to synchronize alternator-2 with alternator-1.

The biggest disadvantage of this method is that it only shows the difference between the alternator-2 and the bus bar by measuring the rate of flickering. However, this method does not provide information on alternator frequency in relation to bus bar frequency.

3. Two Bright and One Dark Lamp Method

This method can be used to determine whether the alternator frequency is lower or higher than the bus bar frequency.

1. Similar to the dark lamp approach, the light L2 is linked across the pole on the middle line of the synchronizing switch, however, the lamps L1 and L3 are connected in a transposed manner.
2. The voltage condition testing is similar to the previous approach, and the lamps will glow bright and black one after another after that. The order in which the lamps become dark and bright determines whether the alternator frequency is lower or greater than the bus bar frequency.
3. The entering generator frequency is higher than the bus bar frequency, as indicated by the sequence of becoming bright and dark L1- L2 – L3. As a result, prime mover control must be used to reduce the alternator speed until the flickering rate is reduced to a minimum.
4. The flickering L1-L3-L2 sequence, on the other hand, indicates that the incoming alternator frequency is lower than the bus bar frequency.
5. As a result, the prime mover increases the alternator’s speed until the rate of flickering is reduced to as low as possible. When lamps L1 and L3 are both equally bright and lamp L2 is dark, the synchronization switch is closed.

The downside of this method is that the phase sequence’s validity cannot be verified. This criterion, on the other hand, is superfluous for permanently connected alternators, where confirming the phase sequence is sufficient for the first time of operation.

References and Image Credits: marine electrical equipment and practice by H.D Mcgeorge, generator arrangement – www.boatnerd.com

How to Synchronize Generators on a Ship? appeared first on Marine Insight - The Maritime Industry Guide

A generator on a ship is known as the heart of the ship. It is that life-line which supports each and every function of the ship. Generator of the ship requires special care, attention, and maintenance for its effective and economic running. Moreover, when it comes to operating a generator on a ship, it’s a totally different ball game.

Unlike the conventional generators that we use on land, a ship’s generator requires a special procedure for starting and stopping it. Though not a very complex one, the process demands a step-by-step system to be followed. Missing even a single step might lead to failure in starting or stopping the generator and can even lead to “black-out”, a situation which everyone on ship tries their best to stay away from. In this article, we bring to you an accurate, step by step procedure for starting and stopping a generator on a ship.

Generator starting procedure

Automatic Start

1. Ÿ  This method is only possible if sufficient amount of starting air is available. The air valves and interlocks are operated like in the turning gear operation.
2. Ÿ  In this method the operator has nothing to do, for the generator starts itself depending on the load requirement.
3. Ÿ  However during the Maneuvering process and in restricted areas, the operator has to start by going into the computer based Power Management System (pms). Once inside the system, the operator needs to go to the generator page and click start.
4. Ÿ  In PMS system, the automation follows sequence of starting, matching voltage and frequency of the incoming generator and the generator comes on load automatically.
5. Ÿ  In case of a blackout condition or a dead ship condition, the operator might have to start the generator manually.

Manual start

The manual process is totally different from the automatic start system. The following steps need to be followed:

1. Ÿ  Check that all the necessary valves and lines are open and no interlock is active on the generator before operating.
2. Ÿ  Generally before starting the generator the indicator cocks are opened and small air kick is given with the help of the starting lever. After this, the lever is brought back to the zero position, which ensures there is no water leakage in the generator. The leakage can be from cylinder head, liner or from the turbocharger .
3. Ÿ  The step is performed by putting the control to local position and then the generator is started locally.
4. Ÿ  In case any water leakage is found, it is to be reported to a senior officer or chief engineer and further actions are to be taken.
5. Ÿ  It is to note that this manual starting procedure is not followed generally on Ums ships, but it is a common procedure on manned engine room.
6. Ÿ  In engine rooms, which have water mist fire fighting system installed, this procedure is not followed because when the engine is given a manual kick with open indicator cocks, small amount of smoke comes out of the heads which can lead to false fire alarm, resulting in release of water mist in the specified area.
7. Ÿ  After checking the leakage, in case of any, the indicator cocks are closed and generator is started again from the local panel.
8. Ÿ  The generator is then allowed to run on zero or no load condition for some time for about 5 minutes.
9. Ÿ  After this the generator control is put to the remote mode.
10. Ÿ  If the automation of the ship is in working after putting in remote mode the generator will come on load automatically after checking voltage and frequency parameters.
11. Ÿ  If  this doesn’t happen automatically, then one has to go to the generator panel in Engine control room and check the parameters.
12. Ÿ  The parameters checked are voltage and the frequency of the incoming generator.
13. Ÿ  The frequency can be increased or decreased by the frequency controller or governor control on the panel.
14. Ÿ  The incoming generator is checked in synchroscope to see if it’s running fast or slow, which means if frequency is high or low.
15. Ÿ  In synchroscope, it is checked that the needle moves in clockwise and anticlockwise direction.
16. Ÿ  Clockwise direction means it is running fast and anti-clockwise means it is running slow.
17. Ÿ  Generally the breaker is pressed when the needle moves in clockwise direction very slowly and when it comes in 11’o clock position.
18. Ÿ  This process is to be done in supervision of experienced officer if someone is doing for the first time, for  if this is done incorrectly the blackout can happen which can lead to accidents, if the ship is operating in restricted areas.
19. Ÿ  Once this is done, the generator load will be shared almost equally by the number of generators running.
20. After this the parameters of the generator are checked for any abnormalities.

Stopping procedure

Automatic Procedure

Ÿ  In this procedure the generator is stopped by going into the PMS system in the computer and pressing the stop button to bring stop the generator.

1. Ÿ  This is to be followed only when two or more generators are running.
2. Ÿ  Even if you trying to stop the only running generator it will not stop due to inbuilt safety. The safety system thus prevents a blackout.
3. Ÿ  When the stop button is pressed the load is gradually reduced by the PMS and after following the procedure the generator is stopped.

Manual Procedure

1. Ÿ  In this procedure the generator to be stopped, is put off load from the generator panel in the Engine control room.
2. Ÿ  The load is reduced slowly by the governor control on the panel.
3. Ÿ  The load is reduced until the load comes on the panel below 100 kw.
4. Ÿ  When the load is below 100kw the breaker is pressed and the generator is taken off-load.
5. Ÿ  The generator is allowed to run for 5 minutes in idle condition and the stop button is pressed on the panel.
6. Ÿ  The generator is then stopped .

You may also like to read: Starting of Emergency generator.

Procedure for Starting and Stopping Generators on a Ship appeared first on Marine Insight - The Maritime Industry Guide

The steam turbine is a heat engine that changes over the high temperature and high strain steam intensity energy to mechanical or electrical energy with its fixed and moving cutting edges and alternators. The steam turbine is an optimal central player and has various purposes. Bigger steam turbines are utilized to work generators in power plants, and more modest turbines can be utilized to run siphons and fans. Steam turbines can go from 0.5 to 200,000 HP. 

Like every other machinery, the turbine generator of the ship also has proper standard operating procedures under sequential starting and shutting down procedures to avoid the trouble-free operation of the whole system. The correct procedure ensures that no part of the machinery goes through any kind of stress- thermal or mechanical. It also helps the ship to operate without wasting any extra time.

The correct operations for the Steam Turbine Generator on board the ship are as follows:

Pre-starting procedures

• The greasing of all bearing points should be monitored carefully.
• Cooling water should flow through all water cooling frameworks.
• Major mover power ( or steam, and so forth as the main impetus) should be checked.
• Pivot the Pump rotor manually.
• The level of fluid at the pull side ought to be checked.
• Conveyance valve shut for Centrifugal Pump if not conveyance valve ought to be open.
• The siphon ought to be warmed step by step by leisurely coursing hot fluid through the siphon.
• The spill-back line or sidestep line ought to be open.

Starting Procedures

• Check turbo generator lube oil sump level and drain it for water. Replenish it if the level is less than normal.
• Start the lube oil priming pump from the local station and check the lube oil pressure. Put the priming pump on auto.
• Check and fill up the Turbine Generator vacuum pump operating water tank to a normal level.

• Check vacuum condenser condensate level from the condensate pump. Put the pump on auto so that the level is maintained all the time.
• Operate the steam drain valve to drain any condensed water from the steam line to avoid excessive hammering and vibration while starting the turbo generator.
• Open the main steam inlet valve for the turbo generator.
• Adjust the gland steam pressure to a normal level.
• Check and open the seawater valves for the vacuum pump cooler, T/G lube oil cooler, and vacuum condenser is opened.
• Start the vacuum pump and bring up the vacuum in the condenser.
• Open condensate pump valves and switch on the pump.
• Check whether the condensate vacuum, gland steam pressure, steam inlet pressure, and lube oil pressure are normal.
• Start turbo generator from the local station and close the drain in the steam line.
• Check first and second stage steam pressure.
• Check condenser vacuum and water level.
• Check lube oil pressure and vibration levels.
• Check turbo generator speed, voltage, frequency, vacuum, condenser level and other parameters.
• Give control to the remote station from the local control and take the TG on load.

Post starting procedures

• Actively examine the steam temperature
• Temperature, pressure, flow, etc., should be thoroughly monitored.
• Check the temperature and vibrations of all bearing points
• Examine the Condenser vacuum framework appropriately.
• Monitor turbine ejector framework 
• Keep typical the condenser level control framework.
• Carefully examine the spillage from the stuffing box.

Shutting down procedure

• Step by step, decrease the load to zero.
• Turn on the auxiliary oil siphon, and verify that the appropriate strain is kept up while the turbine is grinding to a halt.
• Trip the crisis valve. This valve additionally controls the vacuum breaker.
• The hole should be closed from the effort of high pressure; steam is conceded to the chamber at around one psi, and water is shut off.
• Shut down the inventory of cooling or gathering water.
• Close down the gathering gear, and open the channels on the turbine funnelling and packaging.
• Proceed with the auxiliary oil siphon function until the turbine rotor has halted.
• The condenser pneumatic pump is used to dry out the turbine in case it is left dormant for a longer period of time to cool to room temperature. Thus it helps to prevent the wearing off of hardware.

Maintenance of Steam Turbines 

Stream Turbines are important for the production power for the main machines and the auxiliary machines onboard ships. Thus it is very crucial to maintain the steam turbine’s operation and performance to ensure high turbine reliability and smooth functioning of the ship and other machines related to it.

Some of the practices for ideal steam turbine operation are as follows:

Steam quality– Steam should be of the greatest quality. Condensate entanglement in the steam supply increas­es turbine steam rates decreases the steam turbine effectiveness and causes disintegration of steam turbine parts. If steam supply quality is sketchy, a mechanical mixing separator ought to be introduced before the turbine delta to forestall inferior quality steam, captured with condensate, from entering the turbine.

Pipe Expansion and Contraction- Steam piping ought to be inspected, examined, planned, and appropriately introduced to guarantee there will be no unnecessary powers communicated to the turbine spines.

Supply and Exhaust Line Sizing- Steam piping should be intended to give full-line steam strain at the turbine gulf at the full-load limit. The stockpile line size should be calcu­lated for the heap, yet additionally to incorporate the strain drops because of the length of line and framework parts, including valves and fittings. 

Steam Piping Supports-  All steam funneling needs help with the extra weight of the line. The two kinds of help normally utilized practically speaking are inflexible and spring plans. The two kinds are intended to help the funneling, however not to support directing the line for development reasons. Nonetheless, an inflexible help can be utilized to limit the development of channelling in conjunc­tion with an extension joint. Ordinary establishments utilize anchors, supports, and guides.

Precautions

• The steam should be superheated or supersaturated before reaching the turbine.
• Prior to starting the turbine, the administrator must get comfortable with the general channelling design, the working attributes of the unit, and the maker’s working guidelines. Lack of proper knowledge may result in fatal accidents.
• It should be noted that an enormous turbine has close clearances and that extension or mishandling can cause more harm than a small unit.

You may also like to read-Starting and Stopping Procedures of a Boiler on Ship

Starting Procedure for Turbine Generator on Ship appeared first on Marine Insight - The Maritime Industry Guide

Turbine generator is a popular source of clean power generation on ships as they don’t use any type of fuel i.e. heavy or diesel oil. Steam is used for power production in case of turbine generators. Steam is an easy, environmental friendly and cheap form of fuel on ships. For turbine generators, the steam comes from the ship’s steam boiler plant.

In turbine generator, steam is used with high pressure to rotate turbine wherein the thermal energy of the steam gets converted into rotary motion. The turbine is connected to the alternator’s rotor; hence the rotary notion of the turbine is utilized to generate electric power.

Alternate Uses of Steam Turbine

On ships, the steam turbine can also be used as a direct propulsion plant, in which, the turbine shaft is connected to propeller shaft of the ship. Since the speed will be in thousand rpm, reduction gears and reduction systems are used to get a drop in propeller rpm.

The propelling plant of the ship can be driven by steam turbine through a slow speed motor. The turbine generator directly supplies power to these slow speed motors which are connected to the propeller shaft of the ship.

Understanding the Construction of Turbine Generator system

Turbine Prime Mover

A turbine will act as a prime mover in turbo generator and is fitted on the same shaft as of the alternator’s rotor.

Alternator

The alternator is used to convert the rotary motion of the turbine to electrical energy and its output is supplied to the main switch board of the ship.

Steam Control Governor

The governor is used to control the speed of the turbine generator during starting, normal operation and shutting down. It controls the quantity of the steam inlet to the turbine generator.

Steam Control Valve

Different pressure control valves are fitted in the steam line and are controlled using governor for the flow of steam from the ship’s boiler system.

Condensate pump

The condensed steam, after the turbine is further cooled down, is pumped back to the cascade tank by condensate pump.

Vacuum pump for glands

The steam turbine shaft is provided with glands wherein steam is sprayed at a pressure of 0.3~ 0.5 bar so that the vacuum inside the turbine casing doesn’t drop.

Condenser

The heat exchanger acts as a condenser to cool down and condense all the steam from the turbine into water so that it can be pumped back to the hot well.

Vacuum pump header tank

A vacuum pump header tank is provided to cool down the vacuum pump as the later deals with high temperature steam.

An Introduction to Ship’s Turbine Generator appeared first on Marine Insight - The Maritime Industry Guide