Electrical Engineering Answers

A 25 ohms resistor connected in series with a coil of 50-ohm resistance and 150 mH

inductance. What is the power factor (pf) of the circuit?

A salient-pole synchronous generator delivers rated kVA at 0.8 p.f. lagging at rated terminal voltage. It

has Xd = 1.0 p.u. and Xq = 0.6 p.u. If its armature resistance is negligible, compute the excitation

voltage under these conditions.

Calculate the synchronizing torque for unit mechanical angle of phase displacement for a 5,000-kVA,

3-φ alternator running at 1,500 r.p.m. when connected to 6,600-volt, 50-Hz bus-bars. The armature

has a short-circuit reactance of 15%.

A counter has a special counting sequence: 0,5,7,1,0,5,7,1, and so on. Design this counter with minimal number of states. a) Draw a state diagram for the counter b) Construct a state-assigned table including the next state and output c) Draw the circuit diagram for the counter using D flip-flops d) Repeat (c) using T flip-flops e) Repeat (c) using JK flip-flops 

A 3-phase, 16-pole synchronous generator has a resultant air-gap flux of 0.06 Wb per pole. The flux is distributed sinusoidally over the pole. The stator has 2 slots per pole per phase and 4 conductors per slot are accommodated in layers. The coil span is 1500 electrical. Calculate the phase and line induced voltages when the machine runs at 375 rpm.

An ac power generator produces 50 A (rms) at 3600 V. The voltage is stepped up to 100000 V by an ideal transformer and the energy is transmitted through a long distance power line which has a resistance of 100 ohms. What percentage of the power delivered by the generator is dissipated as heat in the long-distance power line?

A single-phase two-wire feeder 1 kilometre long supplies a load of

50 A at 0.707 p.f. lagging, 35 A at 0.8 p.f. lagging and 60 A at 0.9

p.f. lagging at distance of 250 m, 500 m and 1000 m, respectively

from the feeding end. The resistance and reactance of the feeder

per kilometre length are 0.05 and 0.2, respectively. If the voltage

at the far end is to be maintained at 230 V, determine the voltage

at the receiving end?

A two-wire feeder PQR has a load of 100 A at R and 50 A at Q,

both at p.f. 0.707 lagging. The impedance of PQ is (0.03 + j0.05)

Ω and that of QR is (0.07 + j0.015) Ω. If the voltage at the far end

R is to be maintained at 415 V, calculate the voltage at Q and P.