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Q5. (A) Select the correct answer for the alternatives given 1- In transformer, the load current at maximum efficiency is equal to rated load current multiplied by a) Pi Pcu Pi b) [P] 12 Pcu c) Pi d) Pcu 2- When a series de motor is operated without a load, which of the following conditions occur? a) The armature draws excessive current c) The armature will not turn b) The voltage requirement increases d) The armature speeds out of control 3-A 220V shunt motor develops a torque of 216 N.m at an armature current of 40 A. The torque developed when the armature current is 20 A a) 432 N.m b)108 N.m A single phase transformer has maximum effici c) 864 N.m d) SAN

Q5. (A) Select the correct answer for the alternatives given 1- In transformer, the load current at maximum efficiency is equal to rated load current multiplied by a) Pi Pcu Pi b) [P] 12 Pcu c) Pi d) Pcu 2- When a series de motor is operated without a load, which of the following conditions occur? a) The armature draws excessive current c) The armature will not turn b) The voltage requirement increases d) The armature speeds out of control 3-A 220V shunt motor develops a torque of 216 N.m at an armature current of 40 A. The torque developed when the armature current is 20 A a) 432 N.m b)108 N.m A single phase transformer has maximum effici c) 864 N.m d) SAN

Introductory Circuit Analysis (13th Edition)
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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Q5. (A) Select the correct answer for the alternatives given 1-In transformer, the load current at maximum efficiency is equal to rated load current multiplied by a) Peu b) [ Рси 12 Рси c) Pi d) Pi √Pcu 2- When a series de motor is operated without a load, which of the following conditions occur? a) The armature draws excessive current c) The armature will not turn b) The voltage requirement increases d) The armature speeds out of control 3-A 220V shunt motor develops a torque of 216 N.m at an armature current of 40 A. The torque developed when the armature current is 20 A a) 432 N.m b)108 N.m c) 864 N.m d) 54 N.m 4-A single phase transformer has maximum efficiency at 75% of full load. Its copper loss at full load should be a) equal to core loss, b) less than core loss. c) more than core loss, d) equal to 75% of core loss 5- The efficiency of a transformer is 98 % at full-load with 0.8 lagging power factor, what will be the efficiency when supplies full-load with 0.8 leading power factor? a) less than 98 %, b) 98%, c) more than 98 %, 6-During short circuit test of a transformer d) none of the above a) primary is supplied rated voltage, b) primary is supplied full load current at rated voltage c) primary is supplied full load current with small voltage, d) primary is supplied rated kVA 7- A 500kVA transformer has iron loss of 500W and copper losses of 2000W at full load. what is the kVA rating should the transformer operates to achieve maximum efficiency? a)250KVA 15) 500KVA 9 1000KVA 125KVA
Transcribed Image Text:Q5. (A) Select the correct answer for the alternatives given 1-In transformer, the load current at maximum efficiency is equal to rated load current multiplied by a) Peu b) [ Рси 12 Рси c) Pi d) Pi √Pcu 2- When a series de motor is operated without a load, which of the following conditions occur? a) The armature draws excessive current c) The armature will not turn b) The voltage requirement increases d) The armature speeds out of control 3-A 220V shunt motor develops a torque of 216 N.m at an armature current of 40 A. The torque developed when the armature current is 20 A a) 432 N.m b)108 N.m c) 864 N.m d) 54 N.m 4-A single phase transformer has maximum efficiency at 75% of full load. Its copper loss at full load should be a) equal to core loss, b) less than core loss. c) more than core loss, d) equal to 75% of core loss 5- The efficiency of a transformer is 98 % at full-load with 0.8 lagging power factor, what will be the efficiency when supplies full-load with 0.8 leading power factor? a) less than 98 %, b) 98%, c) more than 98 %, 6-During short circuit test of a transformer d) none of the above a) primary is supplied rated voltage, b) primary is supplied full load current at rated voltage c) primary is supplied full load current with small voltage, d) primary is supplied rated kVA 7- A 500kVA transformer has iron loss of 500W and copper losses of 2000W at full load. what is the kVA rating should the transformer operates to achieve maximum efficiency? a)250KVA 15) 500KVA 9 1000KVA 125KVA
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