How does slip affect motor speed?

How does slip affect motor speed?

Slip increases with increasing load – providing a greater torque. It is common to express the slip as the ratio between the shaft rotation speed and the synchronous magnetic field speed. Full-load slip varies from less than 1 % in high hp motors to more than 5-6 % in minor hp motors.

What is the effect of change in rotor resistance on torque slip characteristics?

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 changing the rotor resistance on the slip at max 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.

Is torque directly proportional to slip?

Torque is directly proportional to the square of the supply voltage. Torque is directly proportional to slip. Thus, torque-slip characteristics are linear in the lower slip region.

Which of the following will vary the maximum torque?

Which of the following will vary the maximum torque? The condition for maximum running torque is R = S.X By substituting the above value we can get the maximum torque. Tmax ∝ 1 / (2 X). Therefore the maximum torque will depend on the rotor reactance X only.

What is the effect of rotor resistance on maximum torque and slip corresponding to maximum torque?

Equation of Maximum Torque 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.

How is slip torque calculated?

So, when slip s = R2 / X2, the torque will be maximum and this slip is called maximum slip Sm and it is defined as the ratio of rotor resistance to that of rotor reactance.

What is torque slip?

The torque slip curve for an induction motor gives us the information about the variation of torque with the slip. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the machine.

What is negative slip?

Negative slip: When the theoretical discharge is less than actual discharge is known as negative slip.

How does torque affect the slip of a motor?

As torque decreases, due to extra loading effect, speed further decreases and slip further increases. Again torque decreases as T α1/s hence same load acts as an extra load due to reduction in torque produced. Hence speed further drops. Eventually motor comes to standstill condition.

What are the slip characteristics of an induction motor?

Rotor speed or actual speed is the speed at which rotor rotates. The range of slip is between zero to one and the range of rotor speed is between zero (standstill) and (synchronous speed). Torque slip characteristic is a curve plotted between the torque and the slip of induction motor. It also gives the relationship between torque and slip.

When is the torque of an induction motor low?

2) When the rotor speed is not equal to the synchronous speed but near to the synchronous speed, the slip is very low. In this condition, the is very small and negligible compared to the . If the rotor resistance consider as constant, the torque is proportional to the slip.

When do you use torque for rotor speed?

When rotor speed is very near to synchronous speed i.e. when the slip is very low the value of the term (sX 2) 2 is very small in comparison to R 22 and is neglected. Therefore, torque is given by the expression: In the above expression, all quantities are constant except slip s.