1. Choose the group of electrical power supplies that best fits the identification of "Mains"
No. 1 diesel and No. 2 diesel
2. Which group of electrical services are likely to be supplied from an emergency generator?
Steering gear and alarm system
3. After main power is restored, a timed sequential restart of motor-driven auxilliaries is necessary to avoid:
Generator overload due to many motors starting at simultaneously
4. Choose the group of electrical power supplies that best fits the identification of "Emergency"
Emergency diesel and batteries
5. An electrical power emergency source in a ship is required because:
It satisfies the SOLAS requirements for ship safety
6. When a blackout occurs: what should be your first reaction?
Inform the bridge about the reason for blackout, and expected time to restart.
7. A 3-phase induction motor is rated at 200 A.Its initial direct- on-line starting current will be approximately:
1000 A
8. The earth lamps in a 3-phase system indicate as follows: Red= bright Yellow= dark Blue= dim
no fault - hard earth - light earth
9. An earth fault exists on the blue line of a 100 A bilge pump circuit. A second earth fault occurs on the yellow line of a 10 A ventilation fan circuit. The likely outcome is that:
A short circuit occurs between earth faults and the ventilation fan fuse blows
10. A ships 3 - phase a.c. circuit has 440 V and 220 V transformer linked sections. The effect of a single earth fault on a 220 V line will cause the following earth lamp indication:
In 440 V section: Two lamps bright. In 220 V section: Two lamps bright.
11. The insulation resistance (IR) to earth of a new galley hot-plate is measured to be 30 Mohm. When three identical hot-plates are tested together their combined IR will be:
10 Mohm
12. A motor is protected by a thermal overcurrent relay. After tripping on overload it will not be possible to reset the overcurrent relay because the:
Bimetallic strips need time to cool down
13. A 3-phase A.C. induction motor is running normally at its rated current of 150 A when a single phasing fault (open circuit) occurs in one line. The likely outcome will be:
Line currents: 0 A, 180 A, 180 A. Trip condition: trip on overload.
14. The function of the fuses in a motor starter circuit is to provide:
Short circuit protection.
15. "Protective discrimination" means the progressive grading of sizes/tripping times of:
Line fuses and overcurrent relays
16. If the A.C. line current in a generator is doubled, the heating effect in the stator windings will:
Quadruple
17. When a large motor load suddenly is disconnected from the switchboard and the genarator is AVR controlled, the voltage will:
Initially rise, then reset to the set value.
18. Under normal conditions, the electric power for services supplied from the emergency switchboard is supplied from:
The main diesel generator or shaft generator.
19. Regular (at least weekly) testing of the emergency generator must be performed to check:
Its readiness to perform as specified.
20. Unloading a generator, it is necessary to gradually decrease the load in order to avoid:
Undue overspeeding.
21. The internal e.m.f. generated in the phase windings of an a.c. generator is controlled by:
The diesel speed and excitation current.
22. A 10% reduction in generator speed occurs due to a faulty governor. The likely consequence for each motor powered from this generator is to:
Reduce motor speed by about 10%
23. The pair of instruments necessary for generator synchronising are:
Voltmeter and synchroscope
24. Prior to synchronising, the generator voltage and frequency are respectively controlled by:
AVR and speed governor
25. For ideal synchronising, the phase angle difference between the incomer e.m.f. and the busbar voltage should be:
0°
26. During synchronising, the incoming generator should be running slightly "fast" compared to the busbar frequency.This is to ensure that the:
Incomer picks up as a generator
27. The correct time to synchronise is usually taken to be when the synchroscope reaches the "5 to 12" position. This to allow for:
Circuit breaker operating time
28. After successful synchronising the kW and kVar loading are respectively transfered by the following controls:
Speed governor and voltage regulator
29. For two generators running in parallel, their share of additional load (kW) will be determined by the:
Governor droop settings on each prime mover
30. Generator 1 and 2 are working in parallel. Prime-mover 2 suffers a total fuel loss. The likely outcome is:
No.2 generator trips on reverse power
31. It is possible to operate two similar generators in parallel at equal power (kW) but at different power factors. The generator with lower power factor will cause it to run:
Hotter due to increased current
32. Check-synchroniser equipment is often installed to:
Prevent manual synchronising outside permitted limits
No. 1 diesel and No. 2 diesel
2. Which group of electrical services are likely to be supplied from an emergency generator?
Steering gear and alarm system
3. After main power is restored, a timed sequential restart of motor-driven auxilliaries is necessary to avoid:
Generator overload due to many motors starting at simultaneously
4. Choose the group of electrical power supplies that best fits the identification of "Emergency"
Emergency diesel and batteries
5. An electrical power emergency source in a ship is required because:
It satisfies the SOLAS requirements for ship safety
6. When a blackout occurs: what should be your first reaction?
Inform the bridge about the reason for blackout, and expected time to restart.
7. A 3-phase induction motor is rated at 200 A.Its initial direct- on-line starting current will be approximately:
1000 A
8. The earth lamps in a 3-phase system indicate as follows: Red= bright Yellow= dark Blue= dim
no fault - hard earth - light earth
9. An earth fault exists on the blue line of a 100 A bilge pump circuit. A second earth fault occurs on the yellow line of a 10 A ventilation fan circuit. The likely outcome is that:
A short circuit occurs between earth faults and the ventilation fan fuse blows
10. A ships 3 - phase a.c. circuit has 440 V and 220 V transformer linked sections. The effect of a single earth fault on a 220 V line will cause the following earth lamp indication:
In 440 V section: Two lamps bright. In 220 V section: Two lamps bright.
11. The insulation resistance (IR) to earth of a new galley hot-plate is measured to be 30 Mohm. When three identical hot-plates are tested together their combined IR will be:
10 Mohm
12. A motor is protected by a thermal overcurrent relay. After tripping on overload it will not be possible to reset the overcurrent relay because the:
Bimetallic strips need time to cool down
13. A 3-phase A.C. induction motor is running normally at its rated current of 150 A when a single phasing fault (open circuit) occurs in one line. The likely outcome will be:
Line currents: 0 A, 180 A, 180 A. Trip condition: trip on overload.
14. The function of the fuses in a motor starter circuit is to provide:
Short circuit protection.
15. "Protective discrimination" means the progressive grading of sizes/tripping times of:
Line fuses and overcurrent relays
16. If the A.C. line current in a generator is doubled, the heating effect in the stator windings will:
Quadruple
17. When a large motor load suddenly is disconnected from the switchboard and the genarator is AVR controlled, the voltage will:
Initially rise, then reset to the set value.
18. Under normal conditions, the electric power for services supplied from the emergency switchboard is supplied from:
The main diesel generator or shaft generator.
19. Regular (at least weekly) testing of the emergency generator must be performed to check:
Its readiness to perform as specified.
20. Unloading a generator, it is necessary to gradually decrease the load in order to avoid:
Undue overspeeding.
21. The internal e.m.f. generated in the phase windings of an a.c. generator is controlled by:
The diesel speed and excitation current.
22. A 10% reduction in generator speed occurs due to a faulty governor. The likely consequence for each motor powered from this generator is to:
Reduce motor speed by about 10%
23. The pair of instruments necessary for generator synchronising are:
Voltmeter and synchroscope
24. Prior to synchronising, the generator voltage and frequency are respectively controlled by:
AVR and speed governor
25. For ideal synchronising, the phase angle difference between the incomer e.m.f. and the busbar voltage should be:
0°
26. During synchronising, the incoming generator should be running slightly "fast" compared to the busbar frequency.This is to ensure that the:
Incomer picks up as a generator
27. The correct time to synchronise is usually taken to be when the synchroscope reaches the "5 to 12" position. This to allow for:
Circuit breaker operating time
28. After successful synchronising the kW and kVar loading are respectively transfered by the following controls:
Speed governor and voltage regulator
29. For two generators running in parallel, their share of additional load (kW) will be determined by the:
Governor droop settings on each prime mover
30. Generator 1 and 2 are working in parallel. Prime-mover 2 suffers a total fuel loss. The likely outcome is:
No.2 generator trips on reverse power
31. It is possible to operate two similar generators in parallel at equal power (kW) but at different power factors. The generator with lower power factor will cause it to run:
Hotter due to increased current
32. Check-synchroniser equipment is often installed to:
Prevent manual synchronising outside permitted limits
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