Electrical

Question 1

a) Name one publication dealing with the storage of ship’s batteries. (2)

b) List SEVEN precautions that should be taken when working in an area where
batteries are stored. (14)

Answer 1

a.) code of safe working practice (COWSP)

b.) adequate ventilation must be used

no smoking, naked flames, sparks hot work or non approved electric tools

all appropriate PPE must be worn, like boiler suit and safety boots, especially when handling acid batteries

care should be taken when working on exposed battery terminals as electrical burns are possible and general good housekeeping used to ensure battery space is clean

do not use metal tools in battery space and remove all metal jewellery before entry as if metal comes into contact with battery terminals it will cause a short circuit.

battery cell caps should be securely tightened

do not mix battery acid in non approved containers

Question 2

With reference to secondary cell batteries:

a) State the two types; (4)

b) State four applications on board ship; (4)

c) Describe the maintenance required.(8)

Answer 2

a.) lead acid
alkaline

b.) starting up a lifeboat engine

Aldis lamp - Aldis Lamps are typically positioned on the bridge wing of maritime vessels. They signal Morse code messages via flashing light and are still used to this day as way of communication between ships, both warfighting and merchant.

starting up an emergency generator

fire detection system

emergency lighting

GMDSS - Global Maritime Distress and Safety System

c.) batteries are stored in a hazardous space that must be cleaned. regularly carry out a specific gravity test. top up battery with distilled water if required. keep terminal connections secure and clean. make use of petroleum jelly, this is smeared on battery terminal to protect against corrosion. regularly check battery charge which is measured in voltage. to check voltage preform a test using a multimeter. Ensure batteries are stowed securely. Ensure light fixings are working and are correct type for space. ensure ventilation system is in good operation

Question 3

With reference to electrical distribution systems:

a) State the meaning of the term earth fault; (2)

b) State FOUR different possible causes of an earth fault occurring in an electric
motor; (4)

c) State THREE undesirable consequences of earth faults; (3)

d) Describe ONE method of detecting earth faults. (7)

Answer 3

a.) when electrical current leads in an unintentional or undesired flow path to the ships hull, perhaps due to weak insulation where current can no longer be contained.

b.) - weak insulation so current can no longer be contained

• loose connections touch motor casing, which causes an earth fault
• motor overload which leads to insulation breakdown
• moisture or water ingress, where the motor has water damage

c.) The ships structure can become live risking the potential for a dead short between multiple phases, which can lead to a black out.

high oscillating current throughout the ships structure can cause overheating and sparking , which is dangerous for ships carrying explosive and flammable cargo.

overcurrent protective devices efficiency is reduced due to a reduced potential difference

d.) to detect an earth fault, earth lamps are used. earth lamps are connected from each phase to earth by a test switch in star. when no earth fault is present lamps glow with low and equal intensity. when an earth fault occurs between any phase to earth the lamp that has an earth fault will go dark and the other two will go brighter.

draw earth lamp system

Question 4

a) State four different causes of earth faults. (8)

b) For EACH cause stated in (a) explain how the fault is rectified. (8)

Answer 4

a.) - weak insulation so current can no longer be contained as well as loose connections

• loose connections touch motor casing, which causes an earth fault
• motor overload which leads to insulation breakdown
• moisture or water ingress, where the motor has water damage

b.) To prevent earth faults it is important to ensure that all electrical components are properly installed and maintained.

Additionally, regular inspections should be conducted to identify any potential issues before they become serious.

Regularly check the integrity of the cables. Finally, any equipment that is exposed to moisture should be properly sealed and insulated to prevent the possibility of an earth fault.

if there are loose connections replace and secure the cables.

Use electrical tape to protect against electrical shock and short circuits. It can also be used to secure loose wiring, prevent interference between wires, and provide a moisture barrier. When using electrical tape, it is important to choose the right size and thickness for the job. electrical tape is a temporary solution , it deteriorate over time and can also be affected by heat or moisture. It is important to properly repair or replace damaged wiring to ensure safety.

Identify and mark the cable with a marker pen. labelling helps reduce the time it takes to track down and resolve an issue. labelling the cable to power source also ensures you are capable of easily tracing cables to power source, thus making equipment maintenance or replacements easier.

Question 5

With reference to marine electrical distribution systems:

a) State the meaning of the term insulated neutral. (8)

b) Briefly describe how the location of an earth fault can be found. (4)

Answer 5

a.) Insulated neutral is a system where the main generator neutral points aren’t connected to the ships hull. This system is preferred to be used to be used on low voltage ships operating at 1000VAC because it prevents nuisance tripping of equipment. additionally it allows essential equipment like steering gear motors and navigational lights to run under a single earth fault connection.
- (draw system diagram)

b.) Earth faults are found by a process of elimination. crew is alerted, someone has to keep an eye on the fault monitor and then power can be switched off by racking the main circuit breakers in predetermined order and a general location is established, the exact location can then be found by preforming an insulation resistance test.

Question 6

Explain the meaning of the term earth fault and state why it is undesirable in electrical installations. (6)

Answer 6

An earth fault occurs when electrical current leads in an unintentional flow path to the ships hull perhaps due to weak insulation or an exposed wire where electrical current can no longer be contained. a single earth fault can break down single phase winding, if not fixed then another earth fault can develop. when you have two earth fault this can lead to a short circuit, which causes fires and other problems. earth faults can be caused by loose connections or a motor overload which leads to a breakdown in insulation, moisture and water ingress. To fix weak insulation tie off or replace the cable so its not exposed. if the terminal box has moisture, replace the parts and seals and dry it out.

Question 7

With reference to electrical motors:

a) List FOUR maintenance actions that are necessary for good operation. (8)

b) Describe how to test for electrical faults within in an electrical motor. (8)

Answer 7

a.) make sure the motor is tightly secured and free from vibration effect.

ensure resistance readings are good, this can be done by doing an insulation resistance test.

Check that motor shaft turns freely this can be done turning the shaft by hand when the motor is disassembled and maintenance is being done.

ensure bearings are greased but not overly greased, to prevent wear and tear or any damage.

ensure motor is kept clean and cooling fins are free from dust and moisture residues to prevent water ingress damage and overheating problems.

make sure motor is dissipating heat correctly and there is good ventilation.

ensure electrical connections are secure and correctly labelled.

regularly inspect motor windings to check integrity.

b.) before doing any electrical tests a permit to work must be obtained and a risk assessment carried out to put in place control measures.

to test for electrical faults an insulation resistance test can be done using an insulation resistance tester.

ensure the motor has been isolated and its safe for a electrical test to be carried out.

before carrying out an IR test ensure IR tester is working by touching the two probes together and pressing the test button.

the IR tester should read 0 ohms. this test is done to ensure copper phase windings are adequately insulated from each other. use the IR tester and test probes to test phase to phase. For example U to V, V to W, U to W. ensure readings are a minimum of 1Mohm at 500VDC test voltage, to prove for good insulation.

also check windings are insulated from ground. these readings must be done U to ground, V to ground and W to ground.

another test that can be done is a continuity test. this is done to check the condition of the windings. use a multimeter and set it to ohms and test between each phase. for instance U1 to U2, V1 to V2, W1 to W2. ensure readings are a minimum of 1Mohm.

one other test that can be preformed on an electric motor is a current draw test. this is done to check the current is balanced between the phases and that it matches full current load value on the motor name plate. use a clamp meter on each motor phase and check that current is similar or same to ensure current between phases is balanced.

Question 8

a) Describe how you would overhaul an electric motor that has been flooded with sea water. (8)

b) Explain how to check the insulation resistance of the motor, stating the
minimum acceptable value. (8)

Answer 8

a.) Before you can overhaul an electric motor a risk assessment must be carried out and an electric permit to work must be obtained. then isolate the motor by using the lock out tag out method. dismantle the motor in to two parts the rotor and the stator. bring the parts to the workshop and clean them with freshwater to clean off the salt and seawater ingress damage. once all parts have been cleaned, dry out each part in a dry room, or with a hair dryer or electric heater. once all parts are dry apply varnish to the stator windings. once the varnish has dried electrical tests should be carried out. This includes an insulation resistance test to check for good insulation from phase to phase and phase to ground, to check phases are insulated from the earth. a continuity test to check condition of windings and a current draw test to check current is balanced between phases and it matches full current load provided on the motor name plate. if all test results are acceptable then motor can be reassembled with new bearings and then taken back to the engine room to be put back into service.

b.) before conducting an insulation resistance test you must ensure motor has been safely isolated and test prove test prove is done to ensure equipment is dead. ensure certified and appropriate rated test instruments are used. With the aid of an of an insulation resistance tester set to ohms with a test voltage of 500VDC on a 440VAC motor, touch the two test probes and press test to check equipment is working. then two sets of readings should be obtained one set of readings to test phase to phase. for example U to V, V to W and U to W. the other set of readings is to test phase to ground, so U to E, V to E and W to E. phase to phase readings will check if windings are insulated and phase to earth will check if windings are insulated from earth. the minimum acceptance value is 1Mohm if below this value this shows poor insulation, if reading is 1Mohm or above this shows good insulation. keep a record of the readings for trending purposes and to use as a guide to predict any problems that might occur.

Question 9

With reference to the testing and maintenance of large electric motors:
a) State the minimum satisfactory value of insulation resistance. (2)
b) State the instrument AND the voltage to be used for the insulation resistance
test. (4)
c) State the regular maintenance that is necessary for good electric motor
operation. (10)

Answer 9

a.) The minimum satisfactory value for insulation resistance is 1Mohm

b.) To preform an insulation resistance test an insulation resistance test an insulation resistance tester is used, the voltage to be used is 500VDC for a 440VAC motor.

c.) regularly check motor connections are tightly secured and motor is free from vibration.

ensure regular insulation resistance readings are taken and recorded for trending and fault finding purposes.

make sure motor shaft turns freely by hand

make sure bearings are greased regularly but not overly to prevent seizing

make sure motor body is kept clean and the cooling fins to prevent overheating and ensure there is no water ingress damage

make sure motor dissipates heat quickly and is well ventilated.

ensure motor windings are secure and correctly labelled

regularly check the motor winding conditions and integrity

regularly preform a continuity test to check condition of windings and do a current draw test to check current is balanced between phases and it matches full current load value on motor name plate

Question 10

With reference to small 3 phase electrical motor, driving a transfer pump that is not used on a regular basis, failing to rotate when the start button is pressed:

a) Outline the procedure to determine the possible cause (8)

b) Explain the procedure to remove the motor should it be faulty and require
changing (8)

Answer 10

a.) There are two possible reasons for this motor not starting on e being an electrical problem and the other a mechanical problem.

1. mechanical problems

• one problem could be the motor bearing or gear have seized. to rectify this problem use bearing grease to lubricate the parts. if motor runs when bearings and gear have seized this will lead to overheating.
• another mechanical problem is the motor shaft has seized and will not turn. check to see if shaft can be turned by hand regularly.
• one other problem could be pump blockage, dismantle or detach pump to determine the possible cause.

2. electrical problems

• The motor fuse has been blown so there’s no power. Do a voltage test with a multimeter to check its condition if dead replace fuse
• main circuit breaker has tripped due to a short circuit fault, check if breaker is stuck in the trip position
• motor has suffered an overcurrent trip due to excessive current from motor being drawn to a seized motor shaft. push the reset button on the OCR (overcurrent relay) and see if relay resets.

b.) prior to removing a motor a risk assessment must be carried out and an electrical permit to work must be obtained. then ensure to isolate the motor mechanically and electrically following the ships SMS requirements. to isolate motor electrically rack out the main circuit breaker to switch off the power. then do a prove test prove to check voltage readings with a multimeter to prove motor has been isolated. Then do a lock out tag out method and post signs and notices to let crew know maintenance is being carried out. ensure correct PPE tools, sufficient lighting and appropriate lifting equipment is available. motor can then be uncoupled from the pump and safely stowed to a designated storage space. work area must then be secured until a new motor is fitted to protect the pump.

Question 11

With reference to electrical motors:
a) State the routine maintenance that is necessary. (8)
b) Describe the tests carried out to prove good electrical condition. (8)

Question 12

With reference to the emergency generator:
a) state the checks required prior to starting the engine: (6)
b) describe the routine testing. (10)

Answer 12

a.) check emergency generator FO tank level by visually checking the fuel gauge

check LO sump tank by using the dipstick

check condition of emergency generator batteries

checking cooling water temperature, LO and FO temp

check cooling water level

check turbo charger oil level

check cooling water pressure, lube oil and fuel oil pressure

visually check around the emergency generator for any leaks and listen for any abnormal noises.

b.) the generator onboard a ship is generally tested offload once a week and onload once a month. the following procedure is followed to test a generator offload.

switch generator from automatic to manual control on the control panel

press the start button on the control panel to start the generator engine using the batteries

let the engine run up to speed and let parameters stabilise

check LO pressure and temperature, cooling water temperature and engine rpm

monitor output voltage and frequency

generator can then be stopped using the stop button at the control panel once the person testing the generator is satisfied that everything is working. afterwards switch the generator back to automatic control.

offload testing means he generator isn’t connected to the main bus bar and isn’t supplying any electrical power so hasn’t taken on any load

onload testing is when the emergency generator is connected up to the main bus bar and is underload producing electrical power to essential emergency equipment like emergency lighting, fire detection system, etc

Question 13

State the procedure to be carried out if you found someone you suspected of
having received an electric shock. (16)

Answer 13

Danger Response Airway Breathing Circulation

firstly i would call the bridge for help and let them know any significant details and ask for assistance. visually look around surroundings to check if it is safe to approach the casualty. approach the casualty with extreme caution to make sure i don’t become a casualty myself. use an electric hook to remove casualty from electrical source. once casualty is away from the electrical source of power, check for a response and if necessary provide first aid and or use the CPR procedure. check the casualty’s airway and if conscious and breathing put them into a recovery position and continue monitoring the casualty condition. if necessary contact shore side medical assistance. ask a crew member for a defibrillator to help provide verbal communication to know when to preform CPR and apply shock.

Question 14

State the safety precautions to be taken before investigating faulty electrical machinery. (4)

Answer 14

A risk assessment is carried out by a competent person to put in place control measures. The electrical equipment must be safely isolated and a lock out tag out method used. A prove test prove is carried using a multimeter to test for voltage, this done to ensure equipment has been safely isolated. An electrical permit to work must be obtained to ensure work has been authorised and to make a high risk electrical task safer.

Question 15

a) List FIVE precautions that should be taken before any work is carried out on
electrical equipment. (10)
b) Identify THREE additional precautions to those in Q3(a), if it has become
essential to work near to live equipment. (6)

Answer 15

a.) a risk assessment should be carried out before hand by a competent person to put in place control measures.

electrical equipment must be safely isolated and a lock out tag out method used.

carry out a prove test prove using a multimeter to test for voltage, this is done to ensure equipment is isolated.

an electrical permit to work must be obtained before doing any work.

use sign if working on live equipment, danger sign if working on live equipment and caution if on dead equipment.

correct PPE must be worn like a boiler suit and safety boots, gloves etc. to provide some protection from injury

b.) Introduce safety barriers to ensure engine room crew are aware that live electrical work is being carried out and not to enter the space.

Have another competent person assist you with the work to reduce risk of injury and provide some insight

Use electrically rubber insulated mats to provide further protection make sure they’re flat to surface.

Question 16

a) State THREE underlying causes of electrical equipment failure. (6)

b) State the precautions to be taken before working on the switchboard. (10)

Answer 16

a.) Overloading - when the current has increased over the full load current causing am overload or overcurrent trip

Insulation failure - cable has been exposed or damaged and can no longer contain current

Misuse - when electrical equipment hasn’t been operated or used correctly

b.) Have a competent officer with you to provide assistance, reduce risk of injury and provide technical support.

Ensure you have electrical PPE on and you use insulated tools beforehand and ensure they’re working

Use electrical rubber insulated mats and ensure they’re rated to the voltage of the live equipment you’re working on

Have an electrical rescue hook on standby if available so that if necessary you can pull a casualty away from a live electrical source.

Control access to the area by using safety barriers or tape and signs to signs to make crew aware of where its safe to work

Ensure any conductive metals or objects are at a safe distance away from any live equipment

Isolate electrical power to the switchboard by racking/closing off the circuit breaker feeding the electrical machinery

Use a lock out tag out method to secure and warn against re-closing the circuit breaker

Use a multimeter to test for voltage and thereby carrying out a prove test prove to ensure equipment is isolated

Carry out a risk assessment to introduce Control measures and obtain a permit to work to ensure work is authorised and to minimise risks

Question 17

Describe the procedure for running up and paralleling an alternator onto the switchboard. (16)

Answer 17

ensure crew aren’t doing any maintenance on the generator before its started.

all machinery covers and guards must be in place.

carry out all pre-start checks before hand. this includes a visual inspection of starting air, control air, fuel supply and cooling system pipes and associated equipment for leaks or any abnormalities.

check the LO level in sump tank is adequate by using dipstick high and low level markings.

start the lube oil priming pump and visually inspect to ensure running normally, wait for pressure on gauge to rise to normal.

then open all indicator cocks, ensuring the fuel oil supply is closed as this is the engine blow down stage and then engage the turning gear.

go to local control panel to ensure engine is switched to local control and fuel notch handle is at the correct position (stop), push the start button on control panel to blow engine by air.

blow down procedure is carried out to purge cylinders and indicator cocks of debris, oil moisture or water.

then disengage the turning gear, close all indicator cocks and open fuel supply, afterwards raise fuel notch handle and press start button at local control panel to start generator.

do another safety round to check visually for any leaks or abnormalities whilst generator is running.

before going to engine control room switch generator from local to remote. go to control room to monitor all pressure and temperature parameters, wait for them to stabilise.

keep an eye on the voltage, wait for it be equal to bus bar voltage, set by the AVR, switch synchroscope on and turn selector switch to generator that is being synchronised.

observe the synchroscope rotation and using the governor control, adjust the incoming frequency so its slightly faster than running generator, this is shown by the synchroscope turning slowly clockwise.

when synchroscope is at the 11’oclock position close the circuit breaker to allow for a delay in human reaction time.

when the circuit breaker is closed it will be at the 12’oclock position so phase sequence will be equal.

at this point incoming generator will synchronise with running one and start to produce power.

now the fuel and speed needs to adjusted to balance out the load for both generators.

to do this use the governor controls and carefully adjust till both generators are sharing load at 50%, then finally switch the synchroscope off.

Question 18

Describe the conditions that must be satisfied before paralleling an a.c.
generator with the main electrical switchboard. For each condition described explain how it is achieved. (16)

Answer 18

One condition that must be met before paralleling a generator onto a switchboard is the voltage has to be kept the same for both incoming and running generator. To keep the voltage the same observe the voltmeter, adjustment are made by the automatic voltage regulator (AVR) manual voltage timer found at the switchboard.

Another condition that must be met is the frequency for both generators must be kept the same. This can be achieved by observing the frequency meter and using the governor controls on the synchronisation control panel to adjust the frequency.

The governor controls can also be used to keep the voltage for both generators in same phase rotation. This is done by observing the synchroscope phase rotation indicator and making any adjustments with governor controls provided on the main switchboard synchronisation panel.

Question 19

a) State the conditions that must be satisfied before paralleling an a.c. generator
with the main electrical switchboard. (6)
b) For EACH condition stated in (a) explain EACH of the following:
(i) how it is monitored (4)
(ii) how it is adjusted (6)

Answer 19

a.) - Voltage for incoming and running generator must be kept the same
- Frequency for incoming and running generator must be kept the same
- Voltage for incoming and running generator must be in same phase rotation

b.) (i) - In order to monitor the voltage and keep it the same you must observe the voltmeter found on the synchronisation panel.
- To monitor the frequency for both generators so that it can be kept the same you must look at the frequency meter on the main switchboard.
- To keep the voltage in same phase rotation monitor the synchroscope

(ii) Voltage for incoming and running generator is adjusted by the AVR manual voltage timer.
Governor controls provided on the main switchboard generator synchronisation panel can be raised or lowered to adjust the frequency for the incoming and running generator as well as to keep the voltage in same phase rotation for both generators. When adjusting observe the voltmeter and frequency meter and make sure they match, use the governor controls for incoming and running generator one at a time and carefully so that paralleling is easier.

Question 20

Describe how to manually couple a second auxiliary generator to the main
switchboard and balance out the load. (16)

Answer 20

Firstly before paralleling a generator onto the switchboard and balance out the load you have to carry out all pre start checks such as, doing a visual inspection of the air starting system, control air, fuel oil supply and cooling system pipes and associated equipment for any leaks or abnormalities. Check the LO sump tank level by oil dipstick high and low level markings. Start the LO priming pump and check suction and discharge pressure by using gauges. Then carry out a blow down procedure to purge the cylinders and indicator cocks of any debris, oil and water moisture and then engage the turning gear. Afterwards disengage the turning gear and open fuel supply, start engine from local control panel and raise the fuel notch. Before then heading to ECR switch generator from local control to remote. When you’ve arrived in ECR monitor the pressure and temperature parameters and wait for them to stabilise. Go to generator switchboard and turn on voltmeter and frequency meter. check to see if the incoming generator voltage is the same, if not then adjust by the AVR. Check if the frequency of incoming generator matches if not then adjust by raising or lowering the governor controls. Then turn on the synchroscope and ensure it runs in clockwise direction, this can be adjusted by using governor controls as well. Allow the synchroscope to operate at a rate of 4-5secs per revolution. Afterwards close the main circuit breaker for the incoming generator when the synchroscope is at the 5to12 position. This is to allow for a delay in human reaction time so the phase sequence will be equal. Let both generators run steadily so incoming generator can synchronise with running one and then start to produce electrical power. At this stage auxiliary generator load needs to be balanced out by adjusting the fuel and speed. To achieve this use the governor controls to increase fuel/speed of incoming generator slightly and decrease the fuel/speed of running one slightly. This adjustment will increase the KW of incoming generator and decrease the KW load from running one. Continue to adjust the KW load sharing until both generators load is evenly balanced

Question 21

Explain the procedure to be taken in EACH of the following circumstances in order to prepare a large electrical generator set for maintenance:

a) taking the a. c. generator off electrical load; (6)

b) isolating the machine in order that work may be safely carried out. (10)

Answer 21

a.) on the generator synchronisation panel, put the selector switch from auto to manual. this is done to allow for manual control of generator that is going to be taken offload. keep all other generators on auto. then using the governor controls slowly unload the generator by lowering the fuel intake so that speed and load can be reduced. the speed and load for the running generators will adjust automatically to maintain 60hz and so only monitor the parameters. when the generator load has dropped to a safe level, about 50KW, open the main circuit breaker by turning the ACB (air circuit breaker) control knob to open. afterwards readjust speed and check running generators are maintaining load and running at 60Hz. let generator run a bit for cooling down purposes before securing. finally stop engine by switching control knob to stop on switchboard panel and then ensure engine has fully stopped so isolation of prime mover an alternator can start.

b.) in order to carry out maintenance on a generator the alternator and prime mover has to be isolated. to isolate a prime mover stop or shut down G/E and switch from manual to local control. isolate fuel supply by closing and locking off fuel valve. then close the starting air valve, remove the turning bar to engage interlock. Then isolate the lube oil and jacket water cooling system. to isolate the alternator simply rack out the main circuit breaker and put into lock position whenever any isolation is complete post notices to make crew aware.

Question 22

a) List FIVE protective devices fitted to a main electrical switchboard. (10)
b) State the precautions to be taken before working on the switchboard.

Answer 22

a.) Overcurrent trip relay - when there is a small increase over the full load current. On a motor an overload trip is detected by an overcurrent relay.

Undervoltage relay - when there is a 50% or more voltage drop due to a release mechanism fitted on a G/E circuit breaker. Prevents a circuit breaker of a dead generator being closed on a live bus bar.

Preferential trip - used as protection to prevent a generator being overloaded by shedding off non essential electrical load in the event of an overload trip. After a time delay a preferential trip relay will switch off a predetermined set of non essential loads

Main circuit breaker - fitted as a protection device to prevent a generator from being damaged from an overcurrent trip

Reverse power trip - fitted to avoid loss of electrical power. Its when a generator consumes power instead of generating it. Its also known as a motoring effect where running generator can’t cope with electrical load from the one running in reverse so it will trip due to a reverse power relay.

b.) Have a competent officer with you to provide assistance, reduce risk of injury and provide technical support.

Ensure you have electrical PPE on and you use insulated tools beforehand and ensure they’re working

Use electrical rubber insulated mats and ensure they’re rated to the voltage of the live equipment you’re working on

Have an electrical rescue hook on standby if available so that if necessary you can pull a casualty away from a live electrical source.

Control access to the area by using safety barriers or tape and signs to signs to make crew aware of where its safe to work

Ensure any conductive metals or objects are at a safe distance away from any live equipment

Isolate electrical power to the switchboard by racking/closing off the circuit breaker feeding the electrical machinery

Use a lock out tag out method to secure and warn against re-closing the circuit breaker

Use a multimeter to test for voltage and thereby carrying out a prove test prove to ensure equipment is isolated

Carry out a risk assessment to introduce Control measures and obtain a permit to work to ensure work is authorised and to minimise risks

Question 23

Explain why EACH of the following protective devices are fitted to a main
electrical switchboard (4 marks each)
Reverse power.
Under voltage.
Main circuit breaker
overcurrent.
Preference trips.

Answer 23

Reverse power - used on a switchboard to avoid loss of electrical power and damage to machinery. Reverse power is also known as motoring effect, it occurs when a generator a is consuming power instead of producing it. A running generator will not be able to cope with the electrical load of motoring one and will therefore trip once detected by a reverse power relay

Undervoltage - occurs when the average voltage of equipment falls below rated voltage amount. An undervoltage relay is fitted as protection to prevent circuit breaker of a dead generator being closed onto a live bus bar. Closing the circuit breaker would cause a three phase short circuit fault

Main circuit breaker overcurrent- a main circuit breaker is used as protection to prevent damage from overcurrent, which is current above full current rating of the generator

Preferential trip - protection fitted on a generator to prevent overloading by shedding the generator off non essential electrical loads. In the event of an overload, after a time delay the Preferential trip relay will switch off a predetermined set of non essential loads

Question 24

What protective device stops a main circuit breaker being closed when the generator is not running. (4)

Answer 24

Undervoltage occurs when the average voltage of equipment falls below rated voltage amount. An undervoltage relay is fitted as protection to prevent circuit breaker of a dead generator being closed onto a live bus bar. Closing the circuit breaker would cause a three phase short circuit fault

Question 25

explain what is meant by harmonics?

Answer 25

Harmonics is the term used to describe a distortion in the behaviour of rapidly changing physical quantities such as noise and electricity. Pure notes are noises vibrating at a given frequency but when we talk about ‘harmonics’ we are describing the overtones of the pure note produced by some interference or distortion. In electrical systems the distortion can be extensive and accumulative and therefore the fundamental frequency of 60 Hz would have a second harmonic of 120 Hz and a third harmonic of 180 Hz. The values can keep on rising where the number of the harmonic distortion is multiplied by the fundamental frequency to give the distortion value, for example, the tenth harmonic will be 600 Hz. In speed control circuits of a.c. propulsion motors the high-speed switching action of the electronic components, in the power converters, will cause a harmonic distortion of the original ‘pure’ waveform of the original supply from the generators.

Question 26

what are some of the common and unpredictable effects of excessive harmonic distortion on marine installations

Answer 26

Some of the common and unpredictable effects of excessive harmonic distortion on marine installations include:

• Overheating and sustained damage to bearings, laminations and winding insulation on generators, transformers and induction motors causing early life failure, which could potentially result in fire
• Overheating of the stator and rotor of fixed speed electric motors; risk of bearing collapse due to hot rotors. This is especially problematic on explosion-proof motors with increased risk of explosion, more especially with ExN (non-sparking motors).
• Overheating of cables and additional risk of failure due to resonance. Harmonics also decrease the ability to carry rated current due to ‘skin effect’, which reduces a cable’s effective CSA.
• Disruption in the operation of uninterruptible power supplies (UPS).
• Spurious tripping or failure of sensitive electronic and computer equipment, measurement and protection relays.
• Voltage resonances leading to transient over voltage and over-current failures in the electrical network.
• Electromagnetic interference (EMI) resulting in disruption to communication equipment.
• Malfunction of circuit breakers and fuses.

Question 27

what are some ways to counter act the effects of harmonic distortion?

Answer 27

There are several methods used to counter the effects of harmonic distortion in marine power systems, including:

• Active or passive filters.
• Increasing the number of pulses in power converters by using multiple-phase shifted secondary windings in propulsion motor supply transformers.
• Installing generators with a large sub-transient reactance.

The predominant harmonics that are expected to occur in the electrical power conversion systems are calculated at the design stage. Keeping low THD values on a system will further ensure proper operation of equipment and a longer equipment life span

Question 28

explain what is total harmonic distortion?

Answer 28

Total Harmonic Distortion (THD)

Harmonic distortion can be multiples of either the voltage or current waveforms and the THD is a term used to describe the contribution of all the harmonic waveforms in the electrical power generation and distribution system. It is expressed as a percentage of the ratio of the root mean square (RMS) value of the total harmonic content to the RMS value of the fundamental frequency. Lloyd’s Register rules on harmonic distortion of voltage state are as follows. Unless specified otherwise, the THD of the voltage waveform at any a.c. switchboard or section board is not to exceed 8% of the fundamental for all frequencies up to 50 times the supply frequency and no voltage at a frequency above 25 times supply frequency is to exceed 1.5% of the fundamental of the supply voltage. All other classification societies place a limit of 5% on THD of voltage (THDv). The Institution of Electrical and Electronic Engineers’ (IEEE) Recommended Practice for Electrical Installations on Shipboard (IEEE Standard 45–2002) states: A dedicated propulsion bus should normally have a voltage total harmonic distortion of no more than 8%. If this limit is exceeded in the dedicated propulsion bus, it should be verified by documentation or testing that malfunction or overheating of components does not occur. A non-dedicated main generation/distribution bus should not exceed a voltage total harmonic distortion of 5%, and no single voltage harmonic should exceed 3%.IEC 60034–1, 2004, Rotating Electrical Machines – Part 1: Rating and Performance, requires that the THDv for synchronous motors above 300 kW output should not exceed 5%. It does not specify distortion levels for individual harmonics. However, keeping low THD values on a system will further ensure proper operation of equipment and a longer equipment lifespan.

Question 29

what is the purpose of fuel rack limiter?

Answer 29

During starting period, the turbocharger is out ofnormal operation and therefore diesel engine isalways in the incomplete combustion due to lack ofair, which results in heavy smoke. The fuel rack limiter is usedto avoid excessive fuel injected intocylinder during starting period to avoid heavy smoke.During starting period, the engine automation systemactivate starting solenoid valve to supply compressedair to push the fuel rack limiter piston. A fuel rack limiter valve supplies air to a pneumatic cylinder or fuel rack limiter.The limiting position is set to about 50%load normally.Thelimiting position can be adjusted by guide whenloosening locking screw. On-off valve is for stopping the engine when engine shut down is necessary or over speed trip is activated. This valve provides air to each stop cylinder, connected to each fuel pumps and pulls the rack to cut off fuel to the engine.

Question 30

what are PLCs?

Answer 30

Programmable Logic Controllers

Programmable logic controllers (PLCs), also known as programmable controllers, are solid-state devices where integrated circuits (ICs) are employed to control automation processes. Programmed by using common programming languages, PLCs store and execute instructions, eg sequencing, timing, counting, data acquisition and manipulation.

The essential components of all PLCs are:

 Power supply module

 central processing unit

 memory module

 input/output module.

Question 31

with reference to PLCs what is the power supply module?

Answer 31

Power supply module

The purpose of the power supply module is to provide reliable and stable voltage output to PLC components (examples in Figure 9.2). For critical equipment incorporating PLC control, it is likely that an uninterruptable power supply (UPS) or back up battery arrangement will be incorporated.

Question 32

with reference to PLC what is the memory module

Answer 32

Memory module

Memory is used to store programs and data. Memory organisation can differ depending on manufacturer and model of the PLC. On a basic level memory is split between 2 sections, read only memory (ROM) and random access memory (RAM).

 ROM - This is used by manufacturers to ensure programs or essential data are not lost or over-written. The operating system or main program is likely to be located here

 RAM —- Data can be read from here, but can also be overwritten or replaced. This could be used by PLC processes for keeping temporary data such as feedback signals. RAM is sometimes referred to as volatile as it is open to change and is cleared when power loss occurs.

Question 33

with reference to PLC what is the central processing unit?

Answer 33

Central processing unit

The central processing unit (CPU) is a complex unit that performs functions set by the program contained within system memory and communicates with other components on the PLC network. The main tasks of the CPU are as follows:

 Read data from the input-output (I/O) modules

 interpret data for decision making

 implement arithmetical or logical actions (e.g. give a start signal to a cooling fan motor to reduce temperature).

Question 34

with reference to PLC what is the input/output module?

Answer 34

Input/output modules

The I/O module interface links the CPU, the process data providers (inputs) and the controllable devices (outputs). Input modules gather input signals from devices such as switches, relays, speed sensors, temperature sensors, etc.

Output modules control the desired effect on field components including heaters, motors, lighting, etc. For example, where the temperature in a galley fridge rises above acceptable conditions, the information is recorded by the fridge temperature sensor and passed to the input module. This is then flagged by the CPU, which calculates that the cooling fan should now run. The CPU then orders the output module to send the start signal to the fridge cooling fan.

The two main signals that are used with I/O modules are:

 Discrete

 analogue.

Discrete

There are two states, or conditions, of discrete signals: false (low or 0) and true (high or 1).

Discrete input signals are acquired by the PLC via the discrete input module from various devices, eg pushbuttons, selector switches, level switches, pressure switches and temperature switches.

Discrete output modules supply an output signal to field components. For example this could be a stop/start signal for a heater or on/off for an LED circuit.

Typical Discrete signal values: 0-24 Vdc (eg 0 = off, 24V = on), 0-230 Vac (eg 0 = close, 230V = open).

Analogue

Unlike discrete signals analogue signals are not simply high or low, or true or false. Analogue signals are continuous and can vary in measurement with time. The inputs are acquired via analogue modules from various analogue devices, eg temperature sensors, potentiometers and pressure transducers.

Sending of analogue outputs to field devices is handled by the analogue output modules. These outputs can control devices such as variable speed motors, dimmable lighting, proportional solenoid valves, power output thyristors and step motors.

While ranges vary, typical analogue I/O signal values are 4—20 mA when using current, or 0-120 Vac or 0—10 Vdc if using voltage.

Question 35

with reference to PLC what are programming languages

Answer 35

Programming languages

The primary goal of programming is to automate and optimize complex tasks by creating software programs that can execute these tasks without human intervention. To control a PLC A programming language isused this is a set of instructions written by a programmer to deliver instructions to the computer to perform and accomplish a task.

In visual /graphical coding, programmerscreate software applications using visual elements such as diagrams, flowcharts, and symbolsinstead of traditional lines of code which is text based programming

These languages can be graphical or text based

There are five common languages used for PLC programming:

 Ladder logic diagram (LD or LAD)

 function blocks diagram (FBD)

 instruction list (IL)

 structured text (ST)

 sequential function charts (SFC).

Question 36

Explain how to Troubleshoot PLCs

Answer 36

PLCs are considered reliable when maintained correctly, but failures and malfunctions can occur.

These can be due to a number of reasons:

 Module failure

 damaged or poor network connections

 overheating

dampness/moisture

radio frequency interference

electromagnetic interference

loss of power.

Rectifying the cause of a failure requires a logical fault finding routine. Familiarity with normal PLC operation will aid in this process, as will circuit drawings and the manufacturers’ manuals. Generally, PLCs will have LED indication on the main module.

LED indication can make fault finding easier by guiding the technician to the troublesome part of the circuit. For example. If the LAN LED was illuminated red, it may indicate a network failure and the user can then start checking network modules and connections. If the BAT LED is red, then the back-up battery may be dead. These are only examples, so manufacturer’s drawings and manuals should always be consulted to confirm the corresponding LED indication.

Example of a troubleshooting approach:

1.Check central unit and I/O expansion modules for alarm indication LEDs. Modern PLC installations may have LCD displays on the CPU module that may display alarm codes or fault information.

2.Check the PLC power supply, ensuring that it is on and no alarms have been triggered by a power supply module.

3.Carefully check that all the fuses in the PLC appliance are intact and that there are no loose wires or contaminated terminals.

4.Ensure that there are no environmental conditions affecting the operation, eg humidity, moisture or overheating.

5.Ensure that the I/O status corresponds to the actual input signals from the operator or input device. Compare visual PLC I/O status LEDs with any record of LED status in working/normal conditions.

6.Ensure that shielding and earthing arrangements are sound to prevent EMI and RFI.

7.Verify that the auxiliary components, ie relays, contactors, solenoid valves, etc, operate correctly when a simulated output signal is applied.

8.If the fault remains, reboot the PLC following manufacturer’s instructions.

9.If there is a logic backup (software or memory) available on board, try solving the problem by uploading the program (re-installing the software).

Question 37

Explain what is emergency diesel generator, its purpose and how to safely operate it?

Answer 37

The emergency diesel generator is a self contained diesel engine driven electrical generator set, which is located in a separated room with access from deck. Usually the generator is the self-excited, brush less type and can be set for manual or automatic operation. Auto will be normally selected, with the manual setting being used for testing the generator or in case of auto start failure.
Upon failure of the main diesel generators the emergency generator set will start automatically and connect to the emergency switchboard to maintain supplies to essential services. It is also used to get the ship under power from dead ship condition and will enable power to be supplied to the essential services without the need for external services such as starting air, fuel oil supply and cooling water.
The engine is normally equipped with a self-contained cooling water system which is circulated by an engine-driven pump and cooled in a radiator. Cooling air is forced through the radiator by an engine-driven fan. The cooling water is mixed with anti-freeze in order to prevent freezing of the cooling water in cold conditions and a thermostatic electrical heater is fitted in the cooling water system to maintain the engine in a condition ready for immediate starting. The engine-driven cooling water pump supplies the LO cooler and after leaving the engine, the cooling water flows to the thermostat and back to the radiator or engine circulation pump.
The engine running gear is force lubricated by an engine-driven gear pump which draws oil from the sump tank and discharges it through the cooler and a filter to the lube oil rail. The system is equipped with a pressure regulating valve to prevent over-pressure of the lube oil supply to the engine.
The generator is supplied with fuel from a dedicated tank which is located in the emergency generator compartment. The fuel level into the tank, as per SOLAS requirement should be enough for 18 hrs in case of cargo ships and 36 hrs in case of passenger vessels of continuous running of the generator at maximum nominal load.
The engine is normally started by means of an electric starter motor with power to the motor being supplied by batteries. The batteries are provided with an isolation switch and are maintained in a fully charged condition by a battery charger which operates continuously and is usually equipped with an alarm which is activated if the charger fails.
A back up hydraulic starter is also fitted with the hydraulic power being manually generated via a hand pump. An accumulator charged by the hand pump provides the pressure to drive the hydraulic motor which connects with the flywheel.
Emergency generator hydraulic starter
When in automatic operation only the electric starter motor is utilized. The engine should be started at least once a week and run up to full load monthly.
The emergency switchboard is normally supplied from the main 440V switchboard and when AUTO mode is selected, the emergency generator is started automatically by detecting no-voltage on the emergency switchboard busbar. Usually, three start attempts are available under automatic control, with a start failure alarm in the event of a failure to start.
The emergency generator air circuit breaker (ACB) will connect automatically to the emergency switchboard after confirming the continuation of no voltage and the bus tie breaker on the emergency switchboard, which feeds from 440V main switchboard is opened automatically when no voltage is detected.
The emergency generator is designed to restore power to the emergency switchboard within 45 seconds as per SOLAS requirement. According to SOLAS regulation an emergency generator must be fully operational for up to 10 degree of trim and 22 and a half degrees of list and need to start anytime at 0°C temperature.

So, in order to enable the emergency generator to start automatically in the event of a blackout:
The mode selector switch at the local control panel must be set to the AUTO position.
The fuel tank must always contain sufficient fuel for at least 18 hours of operation at full load.
The battery system must always remain on charge and the batteries must be checked to ensure that they are fully charged. If one of the battery systems fails it must be disconnected and must be replaced at the earliest possible time.

Usually, after power has been restored on the main switchboard the generator ACB and tie breaker will automatically operate and engine will stop. If the automatic system fails, the manual procedure to stop the engine after power restoration is as follow:
Turn the emergency generator operating mode switch to the MANUAL position.
Manually open the emergency generator circuit breaker.
Manually close the normal supply circuit breaker (tie breaker) to the emergency switchboard.
Manually stop the emergency generator by pressing the STOP pushbutton on the engine panel.
After engine stops, turn the emergency generator operating mode switch to the AUTO position.

If for some reason the emergency generators fails to start automatically, then this must be started manually either using battery starter or hydraulic starter mentioned above. The procedure of manual starting of the emergency generator and manual closing of the circuit breaker is, generally as follow:
Check that there are no water, fuel or lubricating oil leaks and that the emergency generator is available for starting and ensure that there is no restriction on the engine starting.
Ensure that the enginecontrol panel is supplied with electrical power.
Ensure that the fuel system is fully primed and that all of the valves from the fuel tank to the engine are open.
Check the water level in the radiator expansion tank add water to the tank if necessary.
The generator heater and switchboard heater must be switched on.
Ensure that the starter batteries are fully charged and that they are able to supply electrical power to the starter motor.
Check the oil level in the engine sump and replenish if necessary.
Turn the engine control panel mode selector switch to the MAN position.
At the engine control panel press the START pushbutton. The engine should turn over on the electric starter motor and should fire. When the engine fires the START pushbutton must be released. The engine governor will regulate the speed to the preset value.
Check that the engine runs smoothly without excessive noise or vibration.
When the engine is running normally and the generator voltage and frequency are correct, the generator may be connected to the switchboard. The emergency generator circuit breaker is closed by pressing the CLOSE/MAN pushbutton on the same panel.

In order to test the interlock between main switchboard and emergency switchboard the procedure is quite simple but requires attention in order to prevent total power loss during test. In this procedure the bus tie breaker (located normally in ECR and EG’s room) need to be manually open and the emergency switchboard will black out. The emergency generator will start automatically and the generator ACB will close to feed the emergency generator. To return to the normal mode, the tie breaker must be manually closed and emergency generator ACB will open and generator will automatically stop after a preset cooling time. The same test can be performed by turning the E/G SEQ TEST switch, located at the emergency switchboard, inside the emergency generator panel, to the ENG & ACB position. The bus tie breaker will receive an open command. However, during live test in presence of a surveyor or PSC officer , they will always ask to manually trip the tie breaker.
It is very important to avoid frequent consecutive start and stop of the emergency generator without cooling down as this will lead to alternator heater or winding failure. Moreover, running the engine on idle before stop will allow the cooling water and lube oil to carry away heat from the combustion chambers, bearings and turbocharger. It is very important for the turbocharger where frequent sudden stops can result in damage to the bearings and seals.
Generally the idling period before stop is set for 5 minutes and the time period should not be extended, as long periods of idling will result in poor combustion and build-up of carbon deposits in the engine combustion chamber, exhaust manifold and turbocharger.

Question 38

what’s the function of a UPS system

Answer 38

UPS systems ensure that critical systems on ships, such as navigation and communication systems, remain operational during power outages or other disruptions. This is essential for maintaining the safety and security of the ship and its crew.

Question 39

Explain What is a blackout and how to recover from a blackout ?

Answer 39

A blackout is an unexpected loss of electricity. Blackout occurs when there is a sudden total loss of electric power in the ship’s main power system It gets very dark and quiet and most machinery comes to a stop, though some diesel engines may still be running as the fuel will be supplied by gravity to these engines. Vessel automation is installed to protect crew from this kind of thing, Power Management Systems (PMS), preferential tripping of non-essential machinery, and sequential start systems help us get going again automatically.
When a blackout happens, the emergency generator should start within 45 seconds and give you back the essential minimum services you need in order to recover. The alarm and monitoring system are normally continuously working as they are supplied, for safety reasons, from vessel batteries.
As soon as you can, you need to inform the Officer of the Watch on the bridge about what is going on and try to be as accurate as possible. Take the main engine control into ECR and move the control lever back to the stop position so that you can re-start the engine later in an orderly way. If the engineer’s alarm hasn’t gone off yet, turn it on now and call the Chief Engineer.
Most of the time, the main engine will have stopped because the electrically driven lubricating oil, fresh water, and sea water pumps have stopped working. If the auxiliary boiler was running, close the main steam stop valve to preserve the steam pressure. and once engineers have reached the engine room and you have enough manpower available it might be a good idea to stop using steam for non-essential services (like accommodation heating, fuel tanks heating, etc), as this will make it easier to get steam pressure quickly back to the fuel oil heaters, which are needed to power back and move the vessel.
It is a good idea to record these things (usually on the whiteboard inside ECR) so that everything can be put back to normal later.
Meanwhile you should try to figure out why the power went out, and the data logger might give us some clues about the events that lead to the blackout. Once the cause of blackout has been found it needs to be fixed, if possible, or isolate the faulty equipment that might be causing it. During a blackout there is a lot to do and everything should be done in an organized fashion, therefore a recovery procedure should be in place, which can guide you through the whole situation, with specific task delegated to engine crew members. On most ships, but not all, we can’t run the main generator and the emergency generator at the same time. We can usually get them to work together, but there are usually two circuit breakers (bus tie breaker and emergency generator breaker) that are set up so that only one can be turned off at a time.
This means that we can use either the main switchboard or the emergency generator to power the emergency switchboard. There is no way that we can’t use the emergency generator to power the main switchboard. So now in case of a black out and automatic start of emergency generator, the emergency switchboard will usually be powered by the emergency generator and the main switchboard will be powered by the main generator with no link between the two.
At some point, after everything is more or less restored, we’ll have to link the main and emergency switchboards back together, which means putting power back into the emergency switchboard from the main switchboard. Normally this operation happens automatically as the tie breaker will close once there is power from the main generator and the emergency generator breaker will open and it will automatically stop.
If this system works then it is great, but if don’t then everything should be manually restored. During manual operation you should keep in mind that anything fed from the emergency switchboard will lose power for a short time and it is important to know what this affects, because it could cause another blackout (for instance, if it is supplying power to the main generator fuel pump). During this change over, essential navigation equipment is usually kept running with the help of individual Uninterruptible Power Supplies (UPS). Restoring manually the power should not be a problem for an engineer, since we do this operation as a routine weekly exercise when we test the emergency generator on load. It is important to note that after connecting the main switchboard to the emergency switchboard again you need to turn off the emergency generator. There have been many times when the emergency generator was left running after the power has been recovered. Also, make sure that all of the controls are back to “Auto” and ready to go for the next time. Now that we have enough power, reset the breakers and turn on all the other machines and systems that need to be on and breakers in the preferential tripping sequence are among these (non-essential machinery). On container vessels which carry large amount of reefer containers and where the energy demand is very high, you need to ensure that reefer breakers are started in an appropriate manner, one by one, in order to avoid main generator overload which can cause another power loss.
Modern power management systems make it less likely for power to go out for no reason, but engineers must be familiar with the specific procedures, where to find the instructions and procedures, and ready to act in case of automation failure.

Question 39

What is Reverse Power?

Answer 39

During a vessel voyage, depending on power requirement (during manoeuvrings, canal transit, shallow waters, using bow/stern thrusters etc.) the engine crew need to run more than one generator. To run two or more generators in parallel, they need to be safely synchronized.
However, if not properly synchronized, these generators can create a dangerous condition known as reverse power. Reverse power on vessel diesel generators can pose significant risks to the overall electrical system and equipment onboard. Synchronization is crucial to ensure the smooth operation of generators, and taking appropriate measures and precautions can prevent reverse power situations.
Reverse power is a condition that occurs when a generator is operating at a higher frequency than the electrical system it is connected to. Reverse power occurs when the power flows from the bus bar or electrical network back into the generator. This situation arises during synchronization when the generator’s rotational speed, voltage, or phase sequence does not match the electrical network. Reverse power can cause damage to the generator, increase fuel consumption, and disrupt the operation of other connected generators.

Question 40

What are some Preventive Measures and Precautions to prevent reverse power?

Answer 40

To avoid reverse power during synchronization, it is vital to implement the following measures and precautions:

Generator Preparation:Ensure that the generator is in good condition and properly maintained. Regular inspections and maintenance routines help identify potential issues beforehand.

Voltage and Frequency Matching:Prior to synchronization, verify that the generator’s voltage and frequency match the electrical network’s requirements. Use precision instruments to measure and adjust the generator’s parameters accordingly.

Phase Sequence Alignment:Confirm that the generator’s phase sequence matches that of the electrical network. Phase sequence meters or phase rotation indicators can be utilized for this purpose.

Protective Relays and Circuit Breakers:Install appropriate protective relays and circuit breakers to detect reverse power situations. These devices will trip and isolate the generator from the network if reverse power occurs.

Synchronization Panel:Employ a synchronization panel equipped with synchroscopes, meters, and alarms. This panel provides visual and audible indications of synchronization status and alerts operators to potential reverse power conditions.

Engineer Training:Ensure that the engineers are well-trained in synchronization procedures and the potential risks associated with reverse power. Regular training sessions and refresher courses help enhance their understanding and vigilance.

Question 41

In the event of reverse power occurring despite preventive measures, what are the troubleshooting steps which can be undertaken?

Answer 41

Immediate Isolation:When reverse power is detected, engineer should immediately disconnect the generator from the network by tripping the circuit breaker or activating protective relays

Fault Analysis:Examine the generator’s settings, synchronization panel readings, and any recorded alarms or indicators. Identify any potential causes such as incorrect phase sequence, voltage mismatch, or frequency deviation.

Corrective Actions:Depending on the fault analysis, take appropriate corrective actions. This may involve adjusting the generator’s voltage, frequency, or phase sequence to match the network requirements. Additionally, inspect and rectify any faulty relays, circuit breakers, or synchronization panel components.

Synchronization Retry:Once the corrective actions are completed, retry the synchronization process while closely monitoring the generator’s behaviour and synchronization panel readings. Confirm that the reverse power condition has been resolved.

Post-Troubleshooting Inspection:Conduct a thorough inspection of the generator and associated equipment to ensure there are no hidden issues that could lead to future reverse power occurrences.