Q1.A. The following results give the open circuit characteristic of de shunt generator running at 300 r.p.m. V. (V) 7.5 I (A) 92 132 162 183 190 212 2 3 4 5 6. 7 Determine the voltage to which machine will excite if field circuit resistance is 40 2 and run at 375 r.p.m. a. What additional resistance would have to be inserted in the field circuit to reduce the voltage to 200v at 375 r.p.m? b. Without additional resistance determine the load current supplied by the generator when its terminal voltage is 200v. ignore armature reaction and assume speed is constant (armature resistance is 0.42). B. Does the transformer works at its maximum efficiency? When and how?

Q1.A. The following results give the open circuit characteristic of de shunt generator running at 300 r.p.m. V. (V) 7.5 I (A) 92 132 162 183 190 212 2 3 4 5 6. 7 Determine the voltage to which machine will excite if field circuit resistance is 40 2 and run at 375 r.p.m. a. What additional resistance would have to be inserted in the field circuit to reduce the voltage to 200v at 375 r.p.m? b. Without additional resistance determine the load current supplied by the generator when its terminal voltage is 200v. ignore armature reaction and assume speed is constant (armature resistance is 0.42). B. Does the transformer works at its maximum efficiency? When and how?

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Electrical Heating Unit

The conversion of electrical energy to heat energy is known as electric heating. The heating system that converts the electrical energy to heat energy for various application is called electrical heating unit. Electricity is employed as the firing mechanism in electric heating systems, which transforms electric current to heat. Electric heaters have heating elements in the form of electric resistors.

Question

Q1.A. The following results give the open circuit characteristic of de shunt
generator running at 300 r.p.m.
Va (V) 7.5
I (A)
92
132
162
183
190
212
2
3
4
5
7
Determine the voltage to which machine will excite if field circuit resistance is
40 2 and run at 375 r.p.m.
a. What additional resistance would have to be inserted in the field circuit to
reduce the voltage to 200v at 375 r.p.m?
b. Without additional resistance determine the load current supplied by the
generator when its terminal voltage is 200v. ignore armature reaction and
assume speed is constant (armature resistance is 0.42).
B. Does the transformer works at its maximum efficiency? When and how?
Q2. A short circuit test on a transformer of 20KVA 2400/240 V 50 Hz gives the
following instruments readings: wattmeter reading: 277 W, voltmeter reading :
68 volts, ammeter reading :8.6 A
a) Obtain the equivalent transformer parameter referred to the low-voltage side.
b) The voltage regulation of the transformer for an (0.760) leading PF load.
c) Draw the phasor diagram of the voltages for the transformer.
d) Determine the efficiency of this transformer at full load if the core loss is 130W.

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