Answer 3 QuestionsQ1: Choose the correct answer:1- In an induction motor, no-load slip is generally-(a) Less than 1% (b) 2%(c) 4%(d) 5%2- A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be--------(c) 5Hz(a) 50Hz(b) 25Hz(d) 2Hz3- The efficiency of 3-phase induction motor is about(a) 100%(b) 80-90%(c) 50-60%(d) Less than 50%4- A double squirrel-cage induction motor has ----------(a) Two series winding in stator(b) Two parallel windings in stator(c) Two parallel winding in rotor(d) Two rotors moving in opposite direction5 The rotor slots are slightly skewed in squirrel cage induction motor to -----(a) Increase the strength of rotor bars(b) Reduce the magnetic hum and locking tendency of rotor(d) Provide ease of fabrication(c) Economize on the copper to be used6- Stable operation of an induction motor is ------(a) Between zero slip and unity slip (b) Between zero slip and slip corresponding to maximum torque(c) Between 6.5 slip and 0.95 slip (d) Between slip corresponding to maximum torque and unity slip7- Iron loss in the rotor of a 3-phase induction motor is negligible due to ----(a) Very low frequency of emf induced in the rotor(b) Very low emf induced in the rotor(c) Very low flux density in rotor parts(d) Constant magnitude of flux linking the rotor core8- The starting current of a 3-phase induction motor is about---------of its full load rated current(a) Half(b) Twice(c) 5 to 7 times (d) 8 to 10 times9- During plugging of an induction motor(a) Phase sequence is reversed(b) A de source is connected to stator(e) One phase is open circaited(d) Power is fed back to mains10- Direct online (D.O.L.) starter is used for induction motorsel(a)Less than 5 h.p. (b) Less than 10 h.p. (c) Greater than 10 h.p. (d) For any capacity

"Since you have posted multiple questions. According to guideline we can answer only three short…

1- In an induction motor, no-load slip is generally- (a) Less than 1% (b) 2% (c) 4% (d) 5% 2- A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be-------- (a) 50Hz (b) 25Hz (c) 5Hz (d) 2Hz 3- The efficiency of 3-phase induction motor is about (a) 100% (b) 80-90% -------- (c) 50-60% (d) Less than 50%

1- In an induction motor, no-load slip is generally- (a) Less than 1% (b) 2% (c) 4% (d) 5% 2- A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be-------- (a) 50Hz (b) 25Hz (c) 5Hz (d) 2Hz 3- The efficiency of 3-phase induction motor is about (a) 100% (b) 80-90% -------- (c) 50-60% (d) Less than 50%

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter51: Electric And Electronic Braking

Section: Chapter Questions

Problem 2SQ: Differentiate between the AC and DC magnetic fields applied to an induction motor stator.

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Similar questions

The frequency of rotor current in an induction motor is slip times the frequency of stator current. slip times the frequency of supply, One by slip times the frequency of stator current. One by slip times the frequency of supply
7- Iron loss in the rotor of a 3-phase induction motor is negligible due to (a) Very low frequency of emf induced in the rotor (c) Very low flux density in rotor parts 8- The starting current of a 3-phase induction motor is about (a) Half (c) 5 to 7 times (b) Twice (d) 8 to 10 times 9- During plugging of an induction motor (a) Phase sequence is reversed (b) A de source is connected to stator (e) One phase is open circaited (d) Power is ied back to mains 10- Direct online (D.O.L.) starter is used for induction motors (a)Less than 5 h.p. (b) Less than 10 h.p. (c) Greater than 10 h.p. (d) For any capacity (b) Very low emf induced in the rotor (d) Constant magnitude of flux linking the rotor core of its full load rated current
3.4 The rotor power output of 3-phase induction motor is 15 k. The rotor copper losses at a slip of 4% will be (a) 600 W (c) 650 W (b) 625 W (d) 700 W
What are the following statements are true for a three-phase induction motor? I. Three-phase induction motor stator winding is fed from a single-phase supply II. Stator carries a three-phase winding III. Rotor carries a short circuited winding a. I,II and III b. I only c. I and II only d. II and III
1. The operation of Commutator in DC Motor is * O a) to convert dc to ac O b) to convert ac to dc O c) to convert fixed dc to variable dc O reverse the current direction in the rotating windings each half turn
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4- An induction Motor is a) Self-starting with high torque c) Self-starting with low torque 5- In three-phase squirrel-cage induction motors a) Rotor conductors are kept open b) Rotor conductor ends are short-circuited through slip rings c) Rotor conductors are short-circuited through end rings d) Rotor conductors are connected to insulation b) Self-starting with zero torque d) Not self-starting
Armature winding of an alternator can also be described as