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Q8. (a) State THREE reasons why switchboard instruments  are supplied via instrument transformers from the power circuits which they monitor.(3)

(b) Explain why it is hazardous to open circuit a current transformer whilst its primary is still energized. (4)

(c) Sketch a circuit diagram showing an ammeter, a voltmeter and a wattmeter fed from a single-phase supply via current and voltage transformers. (5)

(d) An ammeter, a voltmeter and a wattmeter monitoring a single phase supply read 40 A, 240 V and 8 kW respectively.

Calculate the power factor of the circuit. (4)