Q5. Describe the following to protect and control the motors: (i) Using circuit diagram and the current-time characteristics, explain the motor overload protection by thermal overload relay. Explain using a circuit diagram how the motor will automatic shutdown when input (ii) fails? (iii) Explain using circuit diagram the under voltage protection of a motor (iv) Draw the circuit diagram to explain the adjustable-frequency drive for a 3-phase induction motor

Q5. Describe the following to protect and control the motors: (i) Using circuit diagram and the current-time characteristics, explain the motor overload protection by thermal overload relay. Explain using a circuit diagram how the motor will automatic shutdown when input (ii) fails? (iii) Explain using circuit diagram the under voltage protection of a motor (iv) Draw the circuit diagram to explain the adjustable-frequency drive for a 3-phase induction motor

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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Similar questions

A 6-pole, 230-V, 60-Hz, Y-connected, three-phase induction motor has R1=0.50, R2'=0.250, X1=0.7502, X2'=0.52, Xm=1000, and Rc-50022. The friction and windage loss is 150 W. Determine the efficiency of the motor at its rated slip of 1.5%. Use the original equivalent circuit.
A 380 V, 50 Hz, 6-pole, 960 rpm, star connected induction motor has the following parameters: stator and rotor resistances are 1.25 each, and stator and rotor leakage reactance are 1.5 each (magnetising reactance can be neglected). The motor is controlled by simultaneous stator voltage and frequency variation. Voltage boost is not used and the motor is controlled using V/f constant law. The motor is supplied from a three-phase voltage source inverter. The motor operates at 30 Hz. Calculate the ratio of the maximum torque at this frequency with respect to the one at rated frequency, for both motoring and generation. b) For the same 30 Hz operating frequency, calculate ratio of the starting current at this frequency with respec to the starting current at rated frequency. c) Assume that the voltage boost of 20 V (phase voltage) is used. Calculate new value of the phase voltage that would be applied in this case for the operating frequency of 30 Hz. Repeat part b) with this new voltage…
A) At what percentage of slip is the pull-out or breakdown torque of a typical 3-phase squirrel- cage induction motor reached? 21. a) 3% slip b) 10% slip c) 20% slip d) none of the above B) If load is increased beyond the breakdown torque, what happens to the speed of the motor? a) it stops b) it may speed up beyond its rated rpm c) its speed will not change, but its current will go down d) none of the above
When the speed of the dc motor is varied by changing the armature resistance, is to be held constant. O field flux O applied voltage O load current O armature current The starting torque of a three phase slip ring induction motor is to a three phase squirrel cage induction motor. when compared O very low O low same O high
Define slip in an induction motor.
Single phase induction motors are not self-starting. For self- starting purpose we are adding many components with it. One of the components is a starting winding which will be disconnected when the motor reaches about full operating speed. State the necessity of this winding and what would happen if the start switch, capacitor, or start winding fail to open?
7-6. A three-phase, 60-Hz, four-pole induction motor runs at a no-load speed of 1790 r/min and a full-load speed of 1720 r/min. Calculate the slip and the electrical fre- quency of the rotor at no-load and full-load conditions. What is the speed regulation of this motor [Equation (4-68)]?
B. What are differences in term of construction and working principle between Shaded Pole Induction Motor and Capacitor Start Induction Motor?