1. A 3-phase, 50-Hz, star-connected, 2,000 kVA, 2,300-V alternator gives a short-circuit current of 600 A for a certain field excitation. With the same excitation, the O.C. voltage was 900 V. The resistance between a pair of terminals was 0.12 ohms. The field loss is 8500 W, Iron loss = 9100 W, friction and windage loss = 7600 W Find full-load efficiency and regulation at (a)Unity p.f. (b) 0.8 p.f.lagging

Q: A long shunt d.c. compound generator delivers 110 kW at 220 V. If r = 0.01 ohm, r = 0.002 ohm, and…

A: We have been given an long shunt dc compound generator as shown in figure.  Given data, Voltage (V)…

Q: Q5) An alternator has 36 slots per pole. One coil lies in the slots number 1 and 31. Calculate the…

A: The question is about winding pitch.

Power Measurement

According to Blondel's theorem, the total power is measured with one less number of wattmeters than the number of wires present in the system. So, a single-phase and two-wire system will require one wattmeter and a single-phase and the three-wire system will require two wattmeters, and a three-phase and the three-wire system will also require two wattmeters and a three-phase and the four-wire system will require three wattmeter devices. The wattmeter is a device that measures power using one voltage and one current input as shown in the above figure. Multiple current or voltage input pair cables are used by many power analyzers and digital storage oscilloscopes (DSOs) for measuring watts, in effect within a single instrument acting as multiple wattmeters. It is possible to measure three-phase and four-wire power with one correctly specified power analyzer.