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+ Reasons for sparks in the motor and inspection methods

① Excessive sparks caused by motor overload. It can measure whether the motor current exceeds the rated value. If the current is too large, the motor is overloaded.

② The brush and commutator are in poor contact. The reason is: the surface of the commutator is too dirty; the spring pressure is not appropriate, the spring pressure can be adjusted by spring balance or experience; when replacing the brush, the wrong brush is suitable for other models; the brush or brush clamping gap is too large If it is too tight or too loose, use emery cloth too tightly. If it is too loose, replace the brush; the contact surface is too small or the brush direction is backward. The small contact surface is mainly caused by improper polishing method when replacing the brush. The correct grinding method is to press the N320 fine emery cloth between the brush and the commutator (the emery cloth faces the brush, close to the surface of the commutator, and the emery cloth cannot be straightened), and the emery cloth moves along the working direction of the motor.

The brush handle is loose and the brushes are not arranged in a straight line. The greater the deviation of the brush position, the greater the spark.

④ The armature vibration causes excessive sparks. The reason is that the gap between the armature and the magnetic pole is not uniform, which causes the armature winding branch voltage to be different, and the internal current is generated to cause the brush to spark; the bearing wear causes the upper gap between the armature and the magnetic pole to be too large, and the lower gap too small. The axis of the coupling is incorrect; the belt of the belt drive motor is too tight.

⑤ The walkie-talkie is short-circuited. The reasons are as follows: electric brush powder and commutator copper powder fill the commutator slot; the mica between the commutating layers is corroded; the brushes formed during the maintenance of the commutator are not removed in time.

⑥ The position of the brush is not at the neutral point. The reasons are as follows: the position of the brush is moved improperly or the fixing bolts of the brush holder are loose during the maintenance process, resulting in excessive sparks under the brush.

The commutating pole winding is reversed. The way to determine this is to take out the armature and apply low-voltage direct current to the stator. Use a small magnetic needle to test the commutator polarity. Along the direction of motor rotation, the generator is "N--N--S--S", and the motor is "N--S--S--N" (uppercase letters are the main polarity, lowercase letters are the commutation polarity ).

⑧ The exchange pole field is too strong or too weak. If the magnetic field of the commutator pole is too strong, the following signs will appear: a green needle spark, the position of the spark is sliding into the end of the brush and commutator, and the surface of the commutator is burned symmetrically. For generators, the brushes can move an appropriate angle against the direction of rotation; for motors, the brushes can move an appropriate angle in the direction of rotation.

If the magnetic field is too weak, the following signs will appear: The spark is located on the sliding end of the brush and commutator. For generators, the brushes need to move an appropriate angle in the direction of rotation; if it is a motor, the brushes should move an appropriate angle against the direction of rotation.

The commutator is eccentric. In addition to manufacturing reasons, it is mainly caused by improper maintenance methods. The reason for the mica protruding between the commutator plates is that when the commutator slot is cut, the edge mica plates are not cleaned up, and when the commutator plates are worn, the mica plates protrude, causing flashover.

Participate in the desoldering of the armature winding and commutator. Use a multimeter (or bridge) to measure the resistance of two adjacent pieces one by one. If the resistance between one piece and two pieces is greater than the resistance between any other two pieces, it means that the winding between the two pieces is not welded or broken.

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