How to repair explosion-proof motors and what are the common faults?

How to repair explosion-proof motors and what are the common faults?
Maintenance of explosion-proof motors

1、 Appearance inspection:

1. Check whether there are cracks, open welds, or deformations on the motor casing, whether the spare parts are complete, and whether there is any damage.

2. Whether the explosion-proof parts have complete fasteners, and whether there are sliding buckles on the sturdy screws and holes.  

2、 Rotor inspection: After extracting the rotor, remove the inner and outer small covers and check for any damage. The rotor cage bar and end ring should be welded firmly and reliably without any open or virtual welding.

3、 Bearing inspection: Remove the coupling and check for damage. Remove the bearing and check for cracks, peeling, pitting, discoloration, and rust spots

4、 Stator inspection:

1. The stator core and winding surface should be clean, and the winding insulation should not have obvious damage or changes.
2. When all windings are rewound, the insulation level, winding pitch, wire cross-section, etc. should be the same as the original design.
3. Immersion frequency: Immerse no less than 3 times.
5、 Cooling system: Check that the water circuit of the water-cooled motor is unobstructed, the seal is intact, and there is no leakage. Conduct a water pressure test.
 

6、 Explosion proof surface inspection: The repair of all explosion-proof parts of the explosion-proof motor complies with the GB3836.2-2000 standard. 7、 Experiment:

1. The insulation resistance value of the winding should be lower than 5M Ω (660V, 380V), and 1140V should not be lower than 10M Ω.
2. Voltage withstand test: 380V-2000v/min, 660V-2500v/min, 1140V -3000v/min.
3. No load test: The unbalanced value of three-phase no-load current shall not exceed 10%, and the operation shall be smooth without any abnormal noise.

1) Due to improper maintenance and installation, the explosion-proof surface is severely corroded. Therefore, it is necessary to adopt the correct installation process and carefully inspect and maintain according to the maintenance system.

2) The explosion-proof surface has suffered severe mechanical damage. This is caused by improper installation or transportation lifting, and if repair is difficult, a motor of the same type must be replaced.

3) The sealing ring is damaged and does not function as a seal. This is due to improper tightening of the screws. Tightening the screws too tightly and applying excessive force can cause the sealing ring to crack; When the fastening screw is too loose, the sealing ring is susceptible to external corrosion, which can also cause damage and lose its sealing function. Poor sealing ring material can also cause premature damage, so it is necessary to replace it with qualified sealing material.

4) The explosion-proof surface is severely deformed. This is due to insufficient machining accuracy of the components, improper material handling, and improper operation. Uniform force is required during installation, and machining should be carried out according to the accuracy and roughness of the drawing. It is difficult to repair motors with severe deformation of the explosion-proof surface, and it is necessary to replace the motor with a new one if necessary. Slight deformation, caused by improper installation, can be reassembled.