Q5. a) Which has the greater equivalent resistance; two equal capacitors in series or in parallel? Explain with reasons? (6)
b) A circuit has a resistance of 3Ω inductance of 0.01H. The voltage across its end is 60V and the frequency is 50Hz. Calculate
a) the impedance
b) the power factor
c) the power absorbed. (10)
Q5. a) Describe the different type of losses occurring in the Power Transformers. (4)
b) A single-phase power transformer supplied a load of 20 KVA at a P.F of 0.81 (lagging). The iron loss of the transformer is 200 W and the copper loss at this load is 180 W. Calculate
(i) The efficiency
(ii) If the load is now changed to 30 KVA at a p.f of 0.91 (lagging). Calculate the new efficiency
Q4. With respect to Alternators onboard:
a) Briefly explain true power, Apparent power and power factor? (8)
b) The alternator is rated for 750 KVA at 0.85 PF, what is the maximum load (Kilo Watt) that can be put on it? Would you be overloading the alternator if the kilowatt reading were now 620 KW and the power factor 0.80? (8)
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