After motor starting speed is lower than the rated speed:

If several motor also appear such problems tend to power grid voltage is too low.If an electric motor parts electric motor starting a buzz and some vibration,to check whether the stator winding is a power,whether can measure three phase current balance and a buzz vibration check whether the three-phase voltage is too low,but not when no-load motor speed is normal,and the permanent magnet motors for saleloaded speed down.Check the steps: First will start motor racing,such as rotating speed is normal,can clean the motor with light load,such as low speed,load mechanical parts have cut living phenomenon,if no fault in the mechanical parts,motor speed not reduce,can make the motor in the rated load within the scope of operation,if the motor speed dropped,give a person a kind of not move feeling,it is proved that motor has a fault,the cause of this failure is that the extended delta connection of single phase capacitor start induction motor motor into a star,squirrel www.facebook.com/guohong.trading cage rotor broken bar,if it's just around the motor,is likely to be a very like a phase.