As an industrial equipment maintenance engineer, I often face various complex mechanical failures. However, among the numerous cases I have dealt with, the troubleshooting of a DC oil pump motor left a deep impression on me. This was not only a technical challenge but also made me deeply understand the importance of details and patience in the problem-solving process.
Fault Background
One day, I received an urgent call from a customer. The customer reported that after the start-up of their DC oil pump motor, the current gradually increased, rising from the initial 160A to 200A, and was accompanied by an increase in oil pressure from 0.132MPa to 0.145MPa. This abnormal current caused the motor to be unable to operate normally, and this oil pump motor was an important piece of equipment for the entire production line, which must be repaired as soon as possible.
Preliminary Inspection
After arriving at the site, I first conducted a visual inspection of the overall condition of the motor and the pump. The motor housing and the wiring looked normal, with no obvious signs of damage or wear. Subsequently, I tested the electrical system to ensure that the power supply voltage was stable and met the requirements. Since there was no problem with the voltage, I was able to determine that the problem lay within the equipment itself.
Gradual Troubleshooting
Inspection of the Mechanical Part:
I removed the cover of the pump and carefully inspected the inside of the pump cavity. Sure enough, a large amount of impurities were found piled up at the pump inlet, which might be one of the reasons for the increase in the running resistance of the pump. I cleaned these foreign objects and checked the condition of the impeller. Some wear marks were found on the edge of the impeller, but it was not serious enough to cause significant resistance.
When inspecting the bearings, I found that some of the bearings had already been worn, and there was an obvious sense of resistance when they were rotating. Due to the poor condition of the bearings, the load on the motor would increase. I immediately replaced these worn bearings.
Inspection of the Motor Part:
The inspection of the motor was relatively complex. I measured the insulation resistance of the coils, and the value was normal, with no short-circuit phenomenon. However, just to be on the safe side, I still opened the end cover of the motor to check if there were any signs of looseness or aging of the coils. The coils looked to be in good condition.
Then I checked the wiring of the motor to ensure that all the connectors were tightened and there were no signs of looseness or oxidation.
System Pressure and Fluid:
Adjusted the pressure setting of the pump system to ensure it was within a reasonable range. I consulted the relevant technical manual and found that the working pressure of the pump should be slightly lower than the current setting value. So I readjusted the system pressure to 0.130MPa.
I inspected the oil product and found that the viscosity of the oil was slightly high, which might be caused by the recent change of the supplier. After communicating with the customer, we decided to replace it with the oil product with a suitable viscosity that was used before.
Result Verification
After a series of inspections and adjustments, I restarted the motor. To my relief, the current returned to the normal level, stabilizing below 160A, and the outlet oil pressure also remained at the adjusted value of 0.130MPa. All these efforts were highly recognized by the customer, and they expressed their gratitude for the rapid restoration of the operation of the production line.
Experience Summary
I have learned a lot from handling this failure. Firstly, when facing a problem, it is necessary to conduct a gradual troubleshooting from the whole to the part, and not to overlook any detail. Secondly, communication and cooperation are also very important. The customer's feedback on the equipment status and the suggestions for replacing the oil product helped me find the root cause of the problem more quickly.
Through this case, I have not only improved my fault diagnosis skills but also have a better understanding of the responsibility and value as a maintenance engineer. This experience of successfully solving the failure has become a precious memory in my career.
