Aux 1 Unit 15

AC Generators

(a) State THREE devices fitted to the main breakers to protect a.c. generators that are able to run in parallel.(3)
(b) Explain why EACH device stated in part (a) is fitted.(7)

1.Quiz. Study Notes

Answer

(a) State the factor that determines the minimum number of available generators required for a vessel to put to sea.(3)
(b) State SEVEN essential services for the operation of a vessel.(7)

2.Quiz. Study Notes

Answer

With reference to a.c. generators:
(a) explain why they must be synchronised before connecting in parallel;(6)
(b) list TWO devices for ensuring that synchronising is correct;(2)
(c) state how the devices listed in part (b) indicated that synchronising is correct.(2)

3.Quiz. Study Notes

Answer

Describe the routine maintenance that should be carried out on the electrical side of an a.c. generator set.
(10)

4.Quiz. Study Notes

Answer

Describe the FULL procedure for paralleling an incoming a.c generator to another a.c generator connected to the main switchboard.(10)

5.Quiz. Study Notes

Answer

(a) Explain the term single phasing.(2)
(b) State the effects on a motor of single phasing.(6)
(c) State how single phasing may be protected against in the motor starter circuit.(2)

6.Quiz. Study Notes

Answer

Describe the construction of a three phase induction motor of the caged rotor type.(10)

7.Quiz. Study Notes

Answer

(a) Describe the construction of a salient pole a.c. generator rotor.(6)
(b) Explain how many poles would be required for a 50Hz supply, rotational speed of 750rpm.(4)

8.Quiz. Study Notes

Answer

(a) Sketch a block diagram of the layout of a vessel electrical distribution system, including the main and emergency generators and detailing the main consumers supplied by the emergency board.(7)
(b) Describe the MCA recommended procedure for testing the Emergency Alternator.(3)

9.Quiz. Study Notes

Answer