In an AC induction motor, the rotor always spins slightly slower than the stator's magnetic field — that gap is called slip, and it's what makes the motor produce torque. Enter your motor's Synchronous Speed (Ns) and Rotor Speed (Nr) into the Motor Slip Calculator to get the Motor Slip percentage, along with the RPM speed difference and a Motor Condition classification based on your result.
Motor Slip
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Speed Difference
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Motor Condition
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Motor slip is the difference between synchronous speed and rotor speed in an induction motor, expressed as a percentage. It's essential for motor operation as it creates the rotating magnetic field needed for torque generation.
Induction motors require slip to operate because the rotor speed must be less than synchronous speed to induce current in the rotor windings. If there was no slip, there would be no relative motion and no induced current to create torque.
Normal slip for induction motors typically ranges from 2% to 5% at full load. High-efficiency motors may have slip as low as 1%, while older or heavily loaded motors may have slip up to 8%.
Synchronous speed is calculated using the formula: Ns = (120 × f) / P, where f is the supply frequency (Hz) and P is the number of poles. For a 4-pole motor on 60Hz supply, Ns = 1800 RPM.
High motor slip can be caused by excessive load, low voltage supply, rotor resistance issues, mechanical problems, or motor overheating. High slip indicates reduced efficiency and potential motor problems.
Yes, negative slip occurs when the rotor speed exceeds synchronous speed, making the motor operate as a generator. This can happen when the motor is driven by external forces faster than its synchronous speed.
Higher slip generally means lower efficiency because more energy is lost as heat in the rotor. Motors are designed to operate at optimal slip values where efficiency is maximized while maintaining adequate torque.