Q9. a) Sketch a circuit showing how the emergency generator is started, connected to the emergency busbars and how the main busbars are disconnected in the event of a blackout.(6)
b) Explain how an emergency generator can be tested to ensure that it is capable of satisfactorily delivering the rated power.(4)
Q10. With reference to braking of a.c induction motors
(a) Explain why braking may be required (2)
(b) Explain why electrical braking is preferable to mechanical braking (2)
(c) Explain the term plugging (2)
(d) Describe how dynamic braking is achieved (4)
Q11. With reference to the protection of electrical power circuits:
(a) explain discrimination, describing how it is achieved. (5)
(b) state, with reasons, the type of fuses used for protection; (3)
(c) explain preferential tripping. (2)
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