The actual speed of a squirrel cage induction motor is:

• A. Always the value listed on the name plate.
• B. The synchronous speed.
• C. Faster as the motors load increases.
• D. Equal to the synchronous speed minus slip.

Answer: (A)

Actual speed is not a fixed, universal number for an induction motor; it depends on slip, which varies with load. The synchronous speed is the speed the motor would run at if there were no slip (no load), but under real load the rotor lags behind that speed by a value called slip. The speed that a motor actually runs at, for practical design and operation, is the rated speed shown on the nameplate. This value reflects the motor’s performance at its rated load, voltage, and frequency, and serves as the standard reference for the motor’s operating speed. Therefore, in most contexts the speed listed on the nameplate is used as the actual speed figure. The other statements don’t describe typical operation: the motor does not run at synchronous speed under load, increasing load generally reduces speed (increases slip), and while rotor speed does equal synchronous speed minus slip, that slip varies with conditions and is not a fixed number when asked for the motor’s actual speed—the nameplate rating is the practical reference.