What is the effect of following on induction motors: (1) Voltage unbalance (2) Harmonic distortion

What is the effect of following on induction motors: (1) Voltage unbalance (2) Harmonic distortion
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1 Answer

Answer :

i) Effect of voltage unbalance: For three phase motors this leads to unequal currents in the three phase windings that result in unbalance in the fields produced due to which negative phase sequence currents are produced that cause oppositely rotating magnetic field to the normal one, leading to overheating in rotor. Over voltage produces excessive amount of current which increases I2R losses and motor efficiency reduces. 


ii) Effect of harmonic distortion: Due to distortion of the main frequency waveform by harmonics produced due to solid state devices, electromagnetic devices, arcing devices the high frequency harmonics lead to increased copper losses and iron losses that results in over heating of motors (due to the harmonic voltages and resulting currents thereon). This leads to motor failures, lower life and improper torque speed characteristics. 

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