# Induction Motor Calculator

Calculate the synchronous speed, slip and rated torque for an induction motor

Tip: registered users can save calculations.

## Symbols

• f  -  system frequency (Hz)
• nr  - rated (or rotor) speed (rpm)
• ns  - synchronous speed (rpm)
• P   - number of poles
• Pr  - motor rated power (kW)
• S   - motor slip (%)
• Tr  - rated torque (Nm)

## Formulae

Synchronous Speed

${n}_{s}=\frac{120f}{P}$

Rotor Slip

$S=\frac{{n}_{s}-{n}_{r}}{{n}_{s}}×100%$

Note: for locked rotor nr = 0, therefore S = 1. The slip will decrease as the rotor speed increases.

Rated Torque

${T}_{r}=\frac{9550-{P}_{r}}{{n}_{r}}$

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