Magnetic Noise in Induction Motors

Noise in large high voltage induction motors (500Hp–18000Hp) may be airborne or magnetic in nature. Usually, large high voltage induction motors are custom built and tailored to meet customer’s demand. Since every motor is unique in its design, it is imperative to predict accurately the magnetic noise generation during design phase, this way avoiding expensive rework cost and not loosing the customer confidence. Stator – rotor mechanical design, along with careful electrical coil design, can significantly cut down magnetic noise in an induction motor. This paper discusses the various causes and control of magnetic noise in large induction motors. Theoretical noise predictions in large induction motors, along with measured experimental noise data, are presented.