A 10 MVA, 66KV, 50Hz, Y-connected 3-phase alternator has synchronous reactance of 0.635 Ù. It is working at full load at 0.8 lagging p.f. condition. Find torque angle, neglect armature resistance.
2075With a phasor diagram show the effect of increasing the field current of a generator supplying a constant real power and connected to a grid system.
1507Draw the wave shape of armature current in a generator subjected to a sudden three phase short- circuit at its terminals. Define various reactance of generator from this wave shape.
1625A 400 V, 50 Hz, Δ connected synchronous generator has a field reactance of 0.1 Ω and armature resistance of 0.015 Ω. At full load, the machine supplies 1200 A at 0.8 pf lagging. Under full-load conditions, the friction and windage losses are 40 KW and the core losses are 30 KW. What is the machine’s overall efficiency? Ignore any field circuit losses.
1335A generating system will have a total capacity of 300 MW. Find the probable forced outage when the capacity is supplied by two 150 MW units. The operating probability of all units is P=0.98 and forced outage probability rate Q =0.02 .
2139A 500 V shunt motor runs at its normal speed of 250rpm when the armature current is 200A. The resistance of the armature is 0.12 Ω. Calculate the speed when a resistance is inserted in the field reducing the shunt field to 80% of normal value and the armature current is 100A.
2017How do the synchronizing lamps indicate the correctness of phase sequence between existing and incoming alternators?
1566Post New VECL Interview Questions
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