7. What are the reasons for the motor phase loss?
Power supply:
(1) Poor contact in the switch;
(2) Transformer or line disconnection;
(3) Insurance fuses.
Motor:
(1) The motor terminal box screw loose contact is poor;
(2) Poor internal wiring;
(3) The motor winding is broken.
8. What are the causes of abnormal vibration and sound of the motor?
Mechanical aspects:
(1) poor bearing lubrication and bearing wear;
(2) The bearing chamber is too large.
(3) The fastening screw is loose;
(4) There are debris in the motor.
Electromagnetic aspects:
(1) Motor overload operation;
(2) Three-phase current imbalance;
(3) lack of phase;
(4) Short circuit failure of the stator and rotor windings;
(5) The broken part of the welded part of the cage rotor is broken.
9. What are the causes of motor bearing overheating?
The motor itself:
(1) The inner and outer rings of the bearing are too tight;
(2) There are problems with the shape and position tolerance of the parts, such as the coaxiality of the parts such as the base, end cover and shaft;
(3) improper selection of bearings;
(4) The bearing is poorly lubricated or the bearing is not cleaned, and there is debris in the grease;
(5) Shaft current.
Use aspect:
(1) Improper installation of the unit, such as the shaft coaxiality of the motor shaft and the driven device is not satisfactory;
(2) The pulley is pulled too tightly;
(3) The bearing is not well maintained, the grease is insufficient or exceeds the service period, and the hair is deteriorated.
11. What are the reasons for the low insulation resistance of the motor?
(1) The winding is damp or has water intrusion;
(2) accumulation of dust or oil on the windings;
(3) Insulation aging;
(4) The insulation of the motor lead or terminal block is broken.
