latihan soal pasca att3 Maintance and repair of electrical and electronic equipment

Maintance and repair of electrical and electronic equipment

1. As part of the regular maintenance for a paramagnetic oxygen analyser used for measuring the oxygen content ofexhaust gas it is important to keep the sample line filter as clean as possible. Why is this necessary with this type of
   instrument?

1. A high flow rate is required in order to deflect the sensing element

2. The filter may rupture due to the high pressures generated by the sample pump

3. The pressure drop across the filter may damage the sampling pump

4. Pressure variations in the sample chamber can cause errors so restrictions must be kept to a minimum

5. I Don't Know.

2. During maintenance work on a compensated mechanical hydraulic governor air is drawn in to the hydraulic circuitafter draining and lushing out the unit. Which of the actions given in the options is most likely to assist in theremoval of the air from the system?

1. With the governor in operation open the compensation needle valve to introduce instability and disturb theengine load to make the governor hunt

2. Drain the governor again and slowly refill with fresh oil

3. With the governor in operation close the compensation needle valve and disturb the load to make the enginehunt

4. Overfill the governor with fresh ol to force all of the air out

5. IDont Know.

3. A delta connected 3-phase A.C. induction motor is running normally at its rated current of 150 A when a singlephasing fault (open circuit) occurs in one line. The likely outcome will be:

1. Line currents: 75 A, 75 A, 75 A. Trip condition: no trip but speed falls

2. Line currents: 0 A, 180 A, 180 A. Trip condition: trip on overload

3. Line currents: 150 A, 150 A, 150 A. Trip condition: fuses blow on short circuit

4. Line currents: 0 A, 150 A, 300 A Trip condition: trip on overload

5. IDont Know.

4. A 3-phase induction motor is rated at 200 A Full loadline current. Its initial direct- on-line starting current will beapproximately:

1. 1000 A

2. 200 A

3. 5000 A

4. 100 A

5. IDont Know

5. High Voltage (HV) cables are smaller than low voltage cables for a given power rating. Why is this?

1. The HV cable has a thinner wall of special insulation material

2. The HV cable uses Aluminium conductors and therefore requires them to be a smaller cross-sectional area

3. The HV cable uses higher quality copper conductors and therefore requires them to be a smaller cross-sectional area

4. The HV cable carries a smaller current and therefore requires less copper

5. IDon't Know

6. The correct time to synchronise is usually taken to be when the synchroscope reaches the "5 to 12" position and isrotating slowly clockwise. This to allow for

1. Circuit breaker operating time

2. Generator phase difference error

3. Synchroscope pointer time lag

4. Synchroscope error

5. IDon't Know

7. A vapour compression refrigeration system is usually fitted with a number of devices to give protection and control ofthe system. Which of the methods given in the options should be used to test the high pressure cut out duringroutine maintenance and checking of the system?

1. Charge the system with refrigerant until the high pressure cut out operates

2. Gradually shut in the condenser cooling water valve or the condenser refrigerant inlet valve while closelymonitoring the compressor discharge pressure

3. Close the condenser outlet valve and closely monitor the condenser pressure

4. Manually close each of the evaporator coils by switching off the electrical supply to the liquid line solenoid shutoff valves and monitor the condenser pressure

5. I Don't Know.

8. Which of the methods given in the options will give the most accurate test of the accuracy of a bourdon tube typepressure gauge with a range of 0 to 20 bar?

1. Use the fuel injector test pump to check the readings against the test rig master gauge

2. Check the readings against the output gauge from a pressure regulator by connecting it to a regulated testsupply

3. Compare it with the reading from a similar gauge connected to the same pressure source

4. Check the gauge on a deadweight tester

5. I Don't Know

9. The function of the fuses in a motor starter circuit is to provide

1. Short circuit protection

2. Undervoltage protection

3. Overload protection

4. I Don't Know

10. A pressure gauge of the bourdon tube type is reading incorrectly and shows 2 bar when the pressure in the systemis zero. There is no spare available. Which of the options would be the best temporary remedy for this situation?

1. Remove the indicator needle and reposition it to read zero when the system is unpressurised

2. Bend the bourdon tube so that a zero reading is obtained when the system is unpressurised

3. Use a deadweight tester to mark a new scale on the gauge throughout the working range

4. Subtract 2 bar from the gauge reading when checking the pressure

5. IDon't Know

11. Vibration analysis is often used as a conditioning monitoring tool onboard ship as part of the approved plannedmaintenance system. Many vibration measuring instruments are fitted with a harmonic fter/analyser. How would
    these filters normally be used during vibration measurement on a centrifugal pump?

1. To generate an audible sound signal at the same frequency and amplitude as the vibration

2. To isolate a single frequency of vibration associated with one of the pumps components

3. To block out any noise or vibration from the surrounding engine room

4. To sum up all the harmonics of a base frequency to give total vibration for all of the pump's componentssimultaneously

5. I Don't Know

12. A ship has an electrical system rated at 690 Volts. Which voltage level is this?

1. Intermediate voltage

2. Low voltage

3. High voltage

4. Medium voltage

5. I Don't Know

13. After main power is restored (following a blackout), a timed sequential restart of motor-driven auxiliaries isnecessary to avoid

1. Overloading creating earth faults

2. Over-frequency due to overspeed of generator

3. Overvoltage due to current surges

4. Generator overload due to many motors starting at simultaneously

5. I Don't Know

14. A simple level control for a water tank consists of a horizontal lever with a float at one end and a filling valve at theother. The lever is provided with an adjustable pivot positioned between the valve and the float. How will the offset
    in the system be affected under changing demand conditions if the pivot is moved closer to the filling valve?

1. It will increase the offset across the demand range

2. It will reduce the offset throughout the demand range

3. It will increase the offset on high demand but reduce it on low demand

4. It will reduce the offset on low demand but increase it during high demand

5. I Don't Know

15. Which of the following voltage levels would be regarded as high voltage likely to be found on a ship?

1. 660Kv

2.  220V

3. 6.6Kv

4. 690V

5. I Don't Know

16. Which of the methods given in the options should be used to test a remote reading temperature gauge for theauxiliary boiler exhaust gas?

1. Check the resistance change in the sensor over a known temperature range against the resistance values inthe product sheet

2. Fit a spare temperature gauge and see if the readings are the same

3. Place the sensor in a test tank of oil fitted with a heater element and thermometer and check the temperaturegauge at different temperatures

4. Place the sensor in a test tank of water fitted with a heater element and thermometer and check thetemperature gauge at different temperatures

5. IDon't Know.

17. The insulation resistance (IR) to earth of a new galley hot-plate is measured to be 30 Mohm. When three identicalhot-plates on the same supply are tested together their combined IR will be

1. 3 Mohm

2. 90 Mohm

3. 10 Mohm

4. 30 Mohm

5. IDon't Know.

18. 10 A ventilation fan circuit. Both systems are supplied from the ship's 440V supply. The likely outcome is that

1. A short circuit occurs between earth fault and the bilge pump fuse blows

2. An open circuit occurs between earth fault and both motors trip out

3. A short circuit occurs between earth faults and the ventilation fan fuse blows

4. Both motors trip out on overload

5. IDon't Know.

19. Which of the methods given in the options should be used as part of the check of the accuracy of a liquid filled thermometer used in the cold rooms of the ships provisions stores?

1. Place the thermometer in the meat room and check the reading when the refrigeration 

2. Place the thermometer in the meat room and check the reading matches the thermostat setting when the liquid compressor cuts outline valve closes

3. Place the thermometer in a hole drilled into a block of ice to check the zero reading

4. Immerse the thermometer in a mixture of distilled water and ice made from distilled water to check the zeroreading

5. IDon't Know.

20. A power card taken from a diesel engine cylinder using a mechanical indicator has a flat top. Which of the possibleactions given in the options is most likely to correct this irregularity on the power card?

1. Change the indicator spring for one with a higher rating

2. Shorten the cord for the indicator drum drive

3. Lubricate the indicator piston and cylinder

4. Lengthen the cord for the indicator drum drive

5. IDon't Know.

21. The recognised definition of High Voltage equipment is anything that operates at over which of the following levels?

1. 33,000Volts ac or dc

2. 1000Volts ac or 1500Volts dc

3. 1000Volts ac or 750Volts dc

4. 440Volts ac or dc

5. IDon't Know.

22. When checking the zero point on a combustible gas indicator that is to be used to detect hydrocarbon gases in anempty cargo tank which method should be used from the options given?

1. Pass fresh air through the sample chamber

2. Pass methane gas through the sample chamber

3. Pass oxygen gas through the sample chamber

4. Pass carbon monoxide gas through the sample chamber

5. I Don't Know.

23. What could be the cause of a refrigeration compressor running continuously even though normal temperatures forthe cold rooms have been reached?

1. The differential pressure switch for the lubricating oil pressure cut-out is stuck in the closed position

2. Low-pressure cut-out is stuck in closed position

3. High-pressure cut-out is stuck in open position

4. Solenoid valve before the expansion valve stuck in closed position

5. I Dont Know

24. With the set point at the actual desired value, a temperature control system is giving an unacceptably large offset(difference between set point and measured value) on high load resulting in a low system temperature. Which of theactions given in the options should be taken to reduce this effect and therefore achieve closer control of the
    temperature?

1. Reduce the width of the proportional band for the controller

2. Increase the set point to a value above the actual desired value

3. Increase the width of the proportional band for the controller

4. I Don't Know.

25. Which of the following options may be used as a brief summary of how to safely make high voltage equipment accessible?

1. Disconnect, isolate, earth (ground)

2. Shed load, Earth (ground), disconnect, isolate

3. Shed load, isolate. Earth (ground)

4. Disconnect, earth (ground), isolate

5. I Don’t Know

26. Compressed air for instrument and control purposes needs to be of high quality. In order to condition the air filtermodules are usually fitted to remove the contaminants. If there is evidence of oil carry over to the final elements in
    the instrumentation air system what is the most likely cause?

1. The particle removal module is choked

2. The air compressor piston rings need to be renewed

3. The coalescer module is saturated and requires renewal

4. The drier section of the module needs to be regenerated

5. I Don't Know

27. For two generators running in parallel, their share of additional load (kW) will be determined by the

1. The power factor of the additional load

2. The temperature difference between the generator rotors

3. Governor droop settings on each prime mover

4. Voltage droop setting on each AVR

5. I Don't KnoW

28. The earth lamps in a 3-phase system indicate as follows: Red-bright
    condition shown as red yellow blue is correct?

1. light earth- no fault - hard earth

2. light earth hard earth -no fault

3. hard earth - light earth - no fault

4. no fault - hard earth - light earth

5. I Don't KnoW

29. Check-synchroniser equipment is often installed to

1. Ensure fair equal sharing between generators

2. Prevent manual synchronising outside permitted limits

3. Allow auto-synchronising to take place

4. o Permit faster paralleling of generators

5. I Don't KnoW

30. Personnel in a high voltage switchroom smell rotten eggs. What may this indicate?

1. Burning of insulation

2. Problems with a vacuum circuit breaker

3. Arcing at badly coupled bus bars

4. Problems with a gas (SF6) circuit breaker

5. I Don't KnoW

31. Set in local control, isolate the suction and delivery valves then commence work

Isolate the suction and delivery valves then inform the electrician that you are starting work
Ascertain from the senior watchkeeper if it is okay to start work, isolate the valves then commence work
In conjunction with the senior watchkeeper and electrician, isolate valves, electrical supply, automatics andpost Do not operate' signs before commencingwork

I Don't Know

32. Following replacement of a diesel alternator governor the machine is test run on load. It is found that as the load isgradually increased the voltage and the frequency gradually fall to an unacceptable level. The governor isamechanical hydraulic type. Select from the options given the correct adjustment to make to correct the situation

1. The governor droop should be reduced

2. The governor load limit should be reduced

3. The governor droop should be increased

4. The governor load limit should be increasec

5. IDon't Know

33. An electrical power emergency source in a ship is required because

1. The ship's total load can be shared between main and emergency generators

2. The main diesel generator(s) can be taken out of service for overhaul or repair

3. It satisfies the need to be environmentally "friendly"

4. It satisfies the SOLAS (and other) requirements for ship safety

5. IDon't Know

34. A deadweight tester is used to check and calibrate a pressure gauge. The tester consists of a hydraulic pump and ahydraulic chamber and balance weight system. After completing the calibration of the pressure gauge the hydraulic
    pressure should be relieved before removing the weights. Select, from the options given, the main reason for this
    requirement

1. To protect the piston in the hydraulic system from possible impact damage as it may reach the end of its stroke

2. To protect the hydraulic pump from a pressure surge as the weights are removed

3. To protect the pressure gauge from a surge in pressure as the weights are removed

4. To protect the hydraulic balance system from a pressure surge as the weights are removed

5. I Don't Know

35. Which of the following alternatives summarise the benefits of using high voltage on ships?

1. Smaller conductors, insulators and transformers

2. More efficient transformers and electrical machines

3. Smaller cables and better power factors

4. Smaller conductors, machines and switchgear

5. I Don't Know

36. A ships 3 - phase a.c. electrical supply system has 440 V and 220 V sections. The effect of a single short circuitfault to earth on a 220 V line will cause which of the following earth lamp indications

1. In 440 V section: all lamps equally bright. In 220 V section: Two lamps bright one lamp dark

2. In 440 V section: All lamps equally bright. In 220 V section: One lamp dim

3. In 440 V section: One lamp dim. In 220 V section: One lamp dim

4. In 440 section: All lamps equally bright. In 220 section: All lamps dark

5. I Don't Know

37. The refrigeration system for the ships provisions consists of a number of cold rooms served by a central refrigerationsystem. The evaporator coils for the vegetable room are found to be frosting up even though the room is down to
    temperature and the liquid line valve has closed. Select, from the options given, the automatic control componentwhich is likely to be malfunctioning and so cause this condition

1. The low pressure cut out for the compressor

2. Back pressure control valve

3. The liquid line valve for the flour room

4. Thermostatic expansion valve for the meat room

5. I Don't Know.

38. On finding a person apparently unconscious in a High Voltage switch room, which of the following should be done?

1. Trip all breakers and approach victim

2. Raise alarm then drag the victim clear so that they cannot reach live parts while receiving aid

3. Check if the victim is in contact with live parts and if not apply first aid

4. Raise alarm, identify means of isolation and apply before approaching victim

5. I Don't Know.

39. During maintenance of a pneumatically operated, diaphragm actuated control valve the diaphragm is found to besplit. Select, from the options given, a suitable material to use to make a temporary replacement if there is no spare
    diaphragm available

1. Natural rubber sheet of greater thickness and lower elasticity as the original diaphragm material

2. Cotton reinforced rubber insertion sheet of smaller thickness but similar strength as the original diaphragmmaterial

3. Natural rubber sheet of approximately the same thickness and elasticity as the original diaphragm material

4. Cotton reinforced rubber insertion sheet of approximately the same thickness but less elasticity than theoriginal diaphragm material

5. I Don't Know

40. Resistance thermometers are often installed in a thermo-well. Will it matter to the accuracy of the measurement howyou install a resistance element in a thermo-well?

1. Will have a minor influence on the measurement

2. No influence at all

3. Will only result in mechanical problems

4. Wrong installation will result in a major deviation in measurement

41. With reference to the installation of pressure gauges tor steam systems. Complete the tollowing statement from theoptions given. To protect a bourdon tube type pressure gauge which is to be fitted to a steam line it should

1. be fitted with a siphon loop between it and the steam pipe

2. be fitted directly to the steam pipe

3. have its casing filled with water

4. be fitted to the steam pipe using a flexible hose

5. I Don't Know

42. A standard outside micrometer requires regular maintenance, including calibration, in order to ensure accuracy ofmeasurement. How is the accuracy of this type of instrument normally checked? Select the answer from the options
    given

1. By checking the distance between micrometer anvil and spindle with an inside vernier gauge

2. By trying a go/no go gauge between the micrometer anvil and spindle at maximum opening at a commontemperature

3. By measuring a standard gauge block or rod at a common temperature

4. By Checking the distance between the micrometer anvil and spindle with an inside micrometer

5. I Don't Know.

43. Salinometers are often used to monitor water supplies. The most common type of sensing device they use is

1. Strain gauge

2. Inductor capsule

3. Electrodes

4. Capacitance probe

5. I Don't Know.

44. A motor is protected by a thermal overcurrent relay. After tripping on overload it will not be possible to reset theovercurrent relay immediately because the

1. Line contactor spring has to be reset

2. Bimetallic strips need time to cool down

3. Oil dash-pot has to be reset

4. Starter isolator automatically applies an interlock

5. I Don't Know.

45. Personnel in a high voltage switchroom smell ozone. This is likely to indicate which of the following?

1. Transformer overload

2. Vacuum circuit breaker problems

3. Arcing at badly connected bus bars

4. Air circuit breaker problems

5. I Don't Know.