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The slip of induction motor is generally
A) 0 to 1%
B) 2 to 5%
C) 10 to 12%
D) 15 to 20%
2 to 5%
For a standard 3-phase polyphase induction motor operating under normal full-load conditions, the slip typically ranges between 2% and 5% (0.02 to 0.05). At no-load, the slip is even lower, close to 0.5% to 1%, whereas during starting, the slip is equal to 1 (100%).
For a standard 3-phase polyphase induction motor operating under normal full-load conditions, the slip typically ranges between 2% and 5% (0.02 to 0.05). At no-load, the slip is even lower, close to 0.5% to 1%, whereas during starting, the slip is equal to 1 (100%).
s=NsтАЛNsтАЛтИТNтАЛ тАФ Per-unit slip of the induction motor
NsтАЛ=P120fтАЛ тАФ Synchronous speed in RPM
frтАЛ=sтЛЕf тАФ Rotor frequency as a function of slip and supply frequency
An induction motor operates on the principle of electromagnetic induction, requiring a relative velocity between the rotating magnetic field created by the stator (NsтАЛ) and the actual rotor speed (N). If the rotor were to reach synchronous speed (N=NsтАЛ), the slip would become zero, causing the induced electromotive force (EMF) and current in the rotor to drop to zero, eliminating electromagnetic torque. Therefore, the rotor always runs at a speed slightly less than synchronous speed to develop necessary torque.
At no-load, the slip is extremely low, generally around 0.5% to 1%.
At full-load, the slip of a standard commercial induction motor is typically between 2% and 5%.
At starting, rotor speed N=0, making the starting slip s=1 (100%).
Low full-load slip indicates high operational efficiency (EfficiencyтЙИ1тИТs).
Provides good speed regulation with small speed variations from no-load to full-load.
Higher slip values lead to increased rotor copper losses (PcuтАЛ=s├ЧPgтАЛ).
High slip reduces overall efficiency and increases heating in the rotor.
Standard squirrel-cage induction motors in industrial drives like pumps, fans, and blowers.
Constant-speed applications requiring good speed regulation under varying loads.
Option A (0 to 1%) corresponds to light load or near no-load operating conditions.
Option B (2 to 5%) represents the typical rated full-load operating slip range.
Option C (10 to 12%) and Option D (15 to 20%) represent high slip conditions seen in specialized high-slip motors or abnormal heavy overload/stalled conditions.
B is correct тАФ The full-load slip of a standard polyphase induction motor typically ranges between 2% and 5%.
Remember that rotor copper loss is proportional to slip (PrcuтАЛ=s├ЧPinputтАЛ). Keeping full-load slip low (2-5%) ensures rotor copper losses remain small and motor efficiency stays high.