A.4.1 Equipment description
A power plant ash storage has two screw air compressors installed as instrument air sources. The air compressor specifications are 18.5kW, air-cooled units, and the exhaust volume is: 3.1m³/min ,.Motor speed 1480r/min.
A.4.2 Fault phenomenon
The plant has a total of 10 air compressors installed, using the original lubricating oil provided by the manufacturer. Since the lubricating oil is expensive, it is planned to use alternative oil products, which are also synthetic oils. For safety reasons, the new synthetic oil is first tried on two small-power air compressors. After the new synthetic oil was used for 1500h, the #2 air compressor had an electrical serious fault alarm. After further inspection, the cause of the serious fault was that the air compressor carbon deposits caused the motor to overcurrent.
A.4.3 Cause Analysis
After inspection, it was found that there was no carbon deposit inside the #1 air compressor, and it had been running for about 6,000 hours before normal maintenance; #1 and #2 air compressors were operated by two different groups of workers. After investigation, it was confirmed that the members of the #2 air compressor working group did not thoroughly drain and clean the air compressor as required, and had a fluke mentality, which led to the mixing of lubricants with different components and caused carbon deposits.
A.4.4 Preventive measures
(1) Air compressor lubricants should be stored separately as special oils to prevent mixing.
(2) Some air compressors that use different oils should be clearly marked, and a dedicated person should be responsible for refueling to prevent mixing of lubricants.
