Q1: Fill in the blank the correct answer: - A 3- phase,50 Hz induction motor runs at 960 rpm, the number of poles are (a) 2 (b)4 (c) 6 (d) 8 - If full load copper losses in a 3- phase,50 Hz, 4 pole induction motor running at 1425 rpm are 500 W, The rotor input power is a) 5 kW (b) 10 kW (c) 20 kW (d) 50 kW B- Frequency of rotor current in three phase induction motor at starting is (b) less than supply (c) greater than supply (d) slip a) supply frequency -If the rotor bars of a 3- phase induction motor are made deeper, R2 is a) increased at starting (b) decreased at starting (c) increased at running (d) decreased at running 5-The full load slip of a 3-phase induction motor ranges from a) 10% to 20% (b) 20% to 30% (c) 2% to 5% (d) 0.5 % to 1% 5- The advantages of squirrel cage induction motor is that (c) it has good cooling. a) has low starting current (b) it requires less maintenance d) external resistance can be inserted in the rotor circuit - The maximum voltage is induced in the rotor of a 3-phase induction motor when is (a) runs at no load (b) runs at full load (c) blocked (d) reversed direction B- The rotor reactance of a 3-phase induction motor is maximum at ---------- a) full load (b) starting (c) no load (d) half load - Friction an windage losses of a 3-phase induction motor are a) maximum at no load (b) minimum at no load (c) maximum at full load (d) remain the same at all loads 10-If supply voltage of a 3-phase induction motor is increased 2 times, then torque is---------- (a) increased 2 times (b) decreased 2 times (c) increased 4 times (d) decreased 4 times [25 Marks]
Q1: Fill in the blank the correct answer: - A 3- phase,50 Hz induction motor runs at 960 rpm, the number of poles are (a) 2 (b)4 (c) 6 (d) 8 - If full load copper losses in a 3- phase,50 Hz, 4 pole induction motor running at 1425 rpm are 500 W, The rotor input power is a) 5 kW (b) 10 kW (c) 20 kW (d) 50 kW B- Frequency of rotor current in three phase induction motor at starting is (b) less than supply (c) greater than supply (d) slip a) supply frequency -If the rotor bars of a 3- phase induction motor are made deeper, R2 is a) increased at starting (b) decreased at starting (c) increased at running (d) decreased at running 5-The full load slip of a 3-phase induction motor ranges from a) 10% to 20% (b) 20% to 30% (c) 2% to 5% (d) 0.5 % to 1% 5- The advantages of squirrel cage induction motor is that (c) it has good cooling. a) has low starting current (b) it requires less maintenance d) external resistance can be inserted in the rotor circuit - The maximum voltage is induced in the rotor of a 3-phase induction motor when is (a) runs at no load (b) runs at full load (c) blocked (d) reversed direction B- The rotor reactance of a 3-phase induction motor is maximum at ---------- a) full load (b) starting (c) no load (d) half load - Friction an windage losses of a 3-phase induction motor are a) maximum at no load (b) minimum at no load (c) maximum at full load (d) remain the same at all loads 10-If supply voltage of a 3-phase induction motor is increased 2 times, then torque is---------- (a) increased 2 times (b) decreased 2 times (c) increased 4 times (d) decreased 4 times [25 Marks]
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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