08 May Sparking on Commutator
There are a lot of reasons to generate sparking on commutator.We must find the main reason so that clear and improve this trouble.When some reversing troubles happened at D.C. motors,the most frequently thing we do is checking and adjusting the normalization of reversing conditions.We found that motors and other parts of motors are running well.This shows that commutation deterioration result from some parts of motor’s working condition has changed or the surrounding environment has changed during the operation of the motor,which destroyed sliding contact.Commutation will work well after checking and adjusting the motor.
In checking D.C. motors’ troubles of commutation deterioration,it is usually includes the following main items.
A.Measuring resistance between commutator segment.According this way,we will find out whether armature winding is broken, open welding or turn-to-turn short circuit.Or whether riser is fractured and there is short circuit between commutator pieces.The voltage drop method is usually used to check resistance between commutator segment, or a special measuring instrument for resistance between commutator can be used.
B.Measuring for pendulum of commutator. Distorted or deflected commutators make an impact on sliding contacting.Why is it happen? Brush pulsation which is over a certain frequency leads to deterioration of commutation.High speed motor and multiple armature winding motor are more sensitive.
C. For the inspection of the neutral surface of the brush, the position of the neutral line of the brush of DC motor should be strictly on the geometric center line of the main magnetic pole, especially for large motor, reversible motor and high-speed motor. Because when the brush deviates from the neutral line of the main engine, the commutation will lead and delay. The longitudinal axis armature reaction changes the external characteristics of the motor. For the reversible motor, the rotational speed is different under the two turns, and the external characteristics are also different, and the commutation strength is also different under the two turns. When the brush deviates from the neutral position, the motor will produce no-load spark because the commutating element enters the main pole flux region.