Contents
Why there is slip in induction motor rotor?
The interface between the rotor current & revolving magnetic flux can generate torque. Thus, according to Lenz’s law, the rotor starts to turn in the direction of the rotating magnetic field. As a result, the relative speed is equivalent to (Ns – Nr) and it is arranged among them to give rise to slip within the motor.
How is rotor frequency affected by slip speed?
Once the operating slip frequency reaches its maximum value, the rotor current will decrease and, in turn, the output torque will decrease in proportion to 1 / ω s 2 as the stator frequency increases as shown in Fig. 3.51.
Is copper loss is affected by changing load?
core loss is a variable loss in the core. due to alternating magnetic flux educed in core. copper loss is a constant loss its not depend in load & unload…
When S is the slip the rotor copper loss rotor input * []?
Rotor copper loss = S × Rotor input power ∴ Rotor input / Rotor copper loss = 1/S.
What causes motor slip?
Slip depends on motor parameters The traditional way to control wound-rotor-induction-motor speed is to increase slip by adding resistance in the rotor circuit. The slip of low-hp motors is higher than that of high-hp motors because rotor-winding resistance is greater in smaller motors.
What is the impact of slip on rotor current?
When the rotor is stationary, s = 1. Under these conditions, the per phase rotor e.m.f. E2 has a frequency equal to that of supply frequency f. At any slip s, the relative speed between stator field and the rotor is decreased.
How can we reduce the copper loss in transformer?
Copper losses are due to the resistance of the wire in the primary and secondary windings and the current flowing through them. These losses can be reduced by using wire with large cross-sectional area in the manufacturing of the coils.
How do you find the input on a rotor?
Example With Calculations
- The synchronous speed of the motor = (50 ×120) / 6 = 6000 / 6 = 1000 rpm. Slip = (Synchronous speed – Actual speed) = 1000 – 960 = 40 rpm.
- Rotor input = 50 1 = 49 kW.
- Rotor output = Rotor input – Rotor copper loss – Friction and Windage loss.
- Motor efficiency = Rotor output/Motor input.