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FAQ02018 of inverters FAQ

FAQ No. FAQ02018

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Question

We are using an Inverter for speed control. How can we calculate the rotational speed of an induction motor?

Answer



Generally, the speed (N) of an induction motor is expressed by the following formula:

N = (120f/P) × (1 - S) (rpm)

f: Primary frequency

S: Slip

Example:

Where f = 60 Hz, P = 4 poles, and S = 3%,

N = ( (120 × 60) ⁄ 4) × (1 − 0.03) = 1,746 (rpm