Q1: Fill in the blank the correct answer: 1- A 3-phase,50 Hz induction motor runs at 960 rpm, the number of poles are (a) 2 (b)4 (c) 6 (d) 8 2- 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 3- Frequency of rotor current in three phase induction motor at starting is --------- frequency (a) supply (b) less than supply (c) greater than supply (d) slip 4- 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 ----- (b) 20% to 30% (a) 10% to 20% 6- The advantages of squirrel cage induction motor is that (b) it requires less maintenance (a) has low starting current (c) 2% to 5% (d) 0.5% to 1% (c) it has good cooling (d) external resistance can be inserted in the rotor circuit 7- 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 8- The rotor reactance of a 3-phase induction motor is maximum at ---------- (a) full load (b) starting (c) no load (d) half load 9- 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: 1- A 3-phase,50 Hz induction motor runs at 960 rpm, the number of poles are (a) 2 (b)4 (c) 6 (d) 8 2- 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 3- Frequency of rotor current in three phase induction motor at starting is --------- frequency (a) supply (b) less than supply (c) greater than supply (d) slip 4- 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 ----- (b) 20% to 30% (a) 10% to 20% 6- The advantages of squirrel cage induction motor is that (b) it requires less maintenance (a) has low starting current (c) 2% to 5% (d) 0.5% to 1% (c) it has good cooling (d) external resistance can be inserted in the rotor circuit 7- 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 8- The rotor reactance of a 3-phase induction motor is maximum at ---------- (a) full load (b) starting (c) no load (d) half load 9- 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
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![Q1: Fill in the blank the correct answer:
1- A 3-phase,50 Hz induction motor runs at 960 rpm, the number of poles are
(a) 2
(b)4 (c) 6
(d) 8
2- 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
3- Frequency of rotor current in three phase induction motor at starting is --------- frequency
(a) supply
(b) less than supply (c) greater than supply (d) slip
4- 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 -----
(b) 20% to 30%
(a) 10% to 20%
6- The advantages of squirrel cage induction motor is that
(b) it requires less maintenance
(a) has low starting current
(c) 2% to 5%
(d) 0.5% to 1%
(c) it has good cooling
(d) external resistance can be inserted in the rotor circuit
7- 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
8- The rotor reactance of a 3-phase induction motor is maximum at ----------
(a) full load (b) starting (c) no load
(d) half load
9- 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]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9f8f866c-ae7b-4b47-af09-9a1e52458793%2F1cba9492-9ba3-44e7-8671-5dd5e846be66%2Fnpdh83s_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Q1: Fill in the blank the correct answer:
1- A 3-phase,50 Hz induction motor runs at 960 rpm, the number of poles are
(a) 2
(b)4 (c) 6
(d) 8
2- 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
3- Frequency of rotor current in three phase induction motor at starting is --------- frequency
(a) supply
(b) less than supply (c) greater than supply (d) slip
4- 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 -----
(b) 20% to 30%
(a) 10% to 20%
6- The advantages of squirrel cage induction motor is that
(b) it requires less maintenance
(a) has low starting current
(c) 2% to 5%
(d) 0.5% to 1%
(c) it has good cooling
(d) external resistance can be inserted in the rotor circuit
7- 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
8- The rotor reactance of a 3-phase induction motor is maximum at ----------
(a) full load (b) starting (c) no load
(d) half load
9- 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]
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