23. RATINGS OF 3·PHASE INDUCTION MOTORS
- Three-phase induction motors are rated in terms of the following:
(i) Power output in kW ;
(v) Phase (single or three)
(vi) Line current;
(vii) Temperature rise in specified time.
- If a motor is designed to be operated on more than one voltage or at more than one speed by reconnecting the winding, a connection diagram is also given on the name plate.
- Class of motors A, B, C, D, E or F is also to be mentioned on the name plate.
- Standard types of squirrel cage motors are:
- Class A motors-Low-impedance squirrel cage rotor motors.
- Class B motors-High-reactance squirrel cage rotor motors,
- Class C motors-High starting torque, low starting current-double squirrel cage motors.
- Class D motors-High resistance squirrel cage rotor motors.
- Class E motors.
Class F motors.