A thermal power plant is equipped with a motor with a power of 220 kW and a voltage of 6 kV. The shaft end of the motor shaft is a 2322E cylindrical roller bearing, and the non-shaft end is a 6322 deep groove ball bearing. In 2004, when the motor was in operation, the temperature of the bearing at the shaft end was sharply increased, the bearing oil cap was discolored, and the smoke of the burnt smell was accompanied. After the operation of the on-duty personnel stopped the inspection, it was found that the motor shaft extension end bearing burned and was locked with the motor rotor.
1 Accident investigation
After the accident, the maintenance personnel conducted a physical examination of the motor and found that:
(1) The bearing end of the motor shaft is burned, the bearing frame and the roller are worn out seriously, and the outer ring of the bearing turns blue partially;
(2) The bearing chamber has obvious signs of wear and is accompanied by deep cracks;
(3) The rotor shaft is combined with the inner and outer oil caps, and there are many deep wear marks;
(4) The inner and outer oil caps of the motor shaft extension end bearing are burnt.
After the disintegration inspection, the maintenance record of the motor was also checked, and it was found that the motor had replaced the bearings at both ends two years ago. When the bearing was replaced, it was found that there was a problem with the tolerance of the motor shaft end bearing and the bearing chamber, and the bearing was slightly rounded, but it was not treated. After the replacement of the bearing, the motor was replenished only once in February 2004, and there was no maintenance record.
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