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Q9. Describe, with the aid of a circuit diagram, the operation of an automatic voltage regulator (AVR) which employs the use of thyristors. (10)

Q10. with reference to a.c. induction motors:

(a) state, with reasons, the type of fuses used for protection; (2)

(b) explain the effects of single phasing; (3)

(c) describe how thermistors can be used to protect the motor; (3)

(d) state TWO types of relay that provide electrical overload protection. (2)

Q11. (a) Explain, with the aid of a sketch, the principle of operation of an earth leakage detection system of the instrument type (6)

(b) Explain why an insulated neutral system is used extensively on-board ships (2)

(c) State, with reasons, why a single earth fault on an insulated neutral system should always be cleared as soon as possible (2)