Q9. (a) Explain the term power factor. (2)
(b) Explain why it is detrimental to have a low power factor. (2)
(c) Explain, with the aid of phasor diagrams, how a synchronous motor may be used to assist in power factor correction. (6)
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. (a) Sketch a circuit diagram of an emergency generator power supply and distribution system, indicating the essential services provided at 440 volts ac, 220 volts ac and 24 volts dc. (6)
(b) State the regulation pertaining to the emergency generator. (4)
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