ABSTRACT
As a general rule, electric motors are very reliable. Occasionally, though, they do develop faults, particularly where the motor is working close to its power limit. A good sign of the equipment seizing up is if the motor starter has begun tripping. Usually, this is because the motor is overloading due to a problem with the equipment, not because there is a fault with the motor. If the spindle does not rotate freely, then the electricians should check at the fan end of the motor to see if the fan blade has jammed or is jamming. A three-phase motor will normally have three windings, and each winding will have two ends. Three-phase motor windings can be connected in star or delta, sometimes referred to as mesh. Polarisation testing is a test that is carried out to check for any deterioration of the windings due to perhaps a build-up of dust, dirt or moisture.
