# What is the effect of varying rotor resistance on maximum torque and starting torque of induction motor?

Contents

See the Torque – Slip characteristics when rotor resistance is varying. Rotor resistance can be increased upto that when Starting torque becomes equal to Maximum value of torque, because after that Starting torque gets reduced. This value of resistance is called Critical Resistance.

## What is the effect of introducing resistance in the rotor circuit of an induction motor?

If the resistance in the rotor circuit is increased, the slip is increased and the speed of the rotor is decreased.

## What is the relation of the rotor resistance with respect to the starting torque in induction motors?

The maximum torque is inversely proportional to rotor reactance. The maximum torque is independent of rotor resistance. The slip at which maximum torque occur depends upon rotor resistance, R2. So, by varying the rotor resistance, maximum torque can be obtained at any required slip.

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## What is the effect of increased rotor resistance on starting torque and maximum torque of an induction motor?

While high starting torques are desirable, high rotor resistance results in a relatively high slip during normal running operation. The high resistance causes increased losses and reduced efficiency during normal operation.

## What is the effect of rotor resistance on maximum torque and slip corresponding to maximum torque explain with neat diagram?

The maximum torque is independent of the rotor resistance. But the exact location of the maximum torque Ʈmax is dependent on it. The greater, the value of the R2, the greater is the value of the slip at which maximum torque occurs. As the rotor resistance increases, the pullout speed of the motor decreases.

## What is the effect of rotor resistance on starting torque?

Rotor resistance can be increased upto that when Starting torque becomes equal to Maximum value of torque, because after that Starting torque gets reduced. This value of resistance is called Critical Resistance. When slip at starting becomes equal to slip corresponding to maximum torque.

## Which type of motor has high starting torque?

DC motor has high starting torque.In a series motor the same current flows through the armature and the field winding.

## How will you improve the starting torque of a 3 phase induction motor?

There are three ways to improve the starting torque of induction Motor. The across the line starting torque at low speed can be increased by increasing the rotor resistance. This will decrease the efficiency of the motor, and the heat on the rotor.

## What is maximum torque in induction motor?

Hence, the developed torque is maximum when the rotor resistance per phase is equal to the rotor reactance per phase under running conditions. By putting the value of sX20 = R2 in equation (1) we get the equation for maximum torque.

## What is full-load torque in induction motor?

The Full-load Torque is the torque required to produce the rated power of an electrical motor at full-load speed. In imperial units the Full-load Torque can be expressed as. T = 5252 Php / nr (1)

## When rotor resistance is increase the value of maximum torque is?

Rotor resistance can be increased upto that when Starting torque becomes equal to Maximum value of torque, because after that Starting torque gets reduced. This value of resistance is called Critical Resistance. When slip at starting becomes equal to slip corresponding to maximum torque.

## Why skewing is used in induction motor?

The skewing of the rotor reduces the tooth harmonics, and thus prevents the crawling effect. Reduces Magnetic Hum: The skewing helps in reducing the magnetic hum, and the motor runs quieter.

## What is the formula for rotor turns per phase?

What is the formula for rotor turns per phase? Explanation: Firstly, the winding factor for stator is obtained along with the winding factor for stator. Next the ratio of the rotor voltage per phase to the stator voltage per phase.

## What is the relationship between torque and speed in constant type loads?

3. What is the relationship between torque and speed in constant type loads? Explanation: Speed hoist is a perfect example of constant type loads in which torque variation is independent of speed. The speed-torque characteristics of this type of load are given by T=K where K is a constant.

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## Is torque proportional to slip?

Thus, the torque is inversely proportional to slip towards standstill conditions. We can represent the torque-slip characteristic by a rectangular hyperbola. … The maximum torque developed in an induction motor is called the pull-out torque or breakdown torque.

## What is pull-out torque?

: the maximum torque a motor will carry without an abrupt drop in speed. 