Reasons for the rotores blower to trip due to high current
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Our company uses Roots blowers for material transfer, with one unit in operation and another as a backup. Recently, the backup pump has been shutting down due to high current levels whenever the pumps are switched over. Inspections of the equipment showed that the check valve at the outlet was functioning properly, the inlet filter was in good condition, and the bearings were properly lubricated; yet the pump still shuts down due to overcurrent after starting up. For example, during operation of A, after starting B, the outlet safety valve will activate for a short period of time; once A is stopped, operation returns to normal. During a recent pump reversal, after starting Pump B, the current reached its full scale, the rotation speed was significantly low, and the outlet safety valve did not activate. It is initially suspected that the inlet filter is clogged, resulting in excessive suction resistance. After disassembly and inspection, it was confirmed to be in good condition; the manual turning of the shaft was smooth, and upon disassembly the bearings and rotor were found to be normal ； The outlet check valve is easy to disassemble for inspection. Currently, there are doubts regarding this issue: 1. If the outlet pressure is high, then the safety valve does not activate ； The issue of inlet resistance has also been resolved, and the rotor can be rotated smoothly ； The motor runs smoothly at no load ； After the outlet safety valve is removed, start up
The principle of a Roots blower is the same as that of a Roots vacuum pump. Any resistance at the inlet or outlet will cause the current to increase. I have encountered situations where foreign objects fell out at the outlet of a Roots vacuum pump, blocking the pipeline and causing an increase in current; you might find this useful as reference.
The motor overcurrent is caused by the load; the reason for it is unknown
The pressure of the safety valve can be adjusted
The material gets blocked outside the outlet pipe, increasing resistance
In the end, the motor aged and had low insulation; after replacing it, it operated normally
The outlet resistance is high; you can try disconnecting the outlet to see.