Reasons for the shutdown of submersible centrifugal pumps
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Hello, everyone! I would like to ask everyone: This unit is equipped with an submersible centrifugal pump, and during normal operation it suddenly stopped working (without any adjustment to the load). As soon as this was noticed, the pump was started again on site. During the first attempt to start it, the frequency conversion setting was set to 0; after the pump started, the frequency was increased to 20%, but the pump stopped working again. During the second start-up, the frequency conversion is first increased to 20% to initiate operation, after which the pump shuts down. During the third start-up, the frequency conversion is first increased to 50% for startup; once operation is normal, it is gradually increased to 70% for operation. The reason for the trip was the activation of the overcurrent protection; the rated current of this pump is 244A, while it was around 348A at the time of the trip. However, since this pump was put into operation, it has been started and stopped multiple times; each time it was started, the procedure of setting the frequency to 0, starting the pump, and then increasing the frequency was followed, and no shutdowns occurred. So, what causes the above problems? Please let me know! Thank you!
It seems that when such things happen, it can’t be said that using an inverter motor under load is the right approach. Perhaps a caching issue has occurred, and it’s possible to resolve it after a few attempts. If possible, it is estimated that the pump will be able to start when it is turned on next time, following the old procedure. The key issue is that it is recommended to disassemble the pump and thoroughly investigate the cause.
The pump will definitely be rotated before it is started; if there is a jam at some point, the operator surely won’t start the pump, right?
A simple solution is to try starting the device at the mains frequency by disabling variable frequency control, or to use a Inverter of the same specifications; this can help determine quickly whether there is an electrical issue. Then consider further investigation from the perspective of disassembling and overhauling the pump.
If non-electrical issues are ruled out, there must be a problem with the pump itself
Was the crankshaft venting done in accordance with the procedures?
To be honest, driving the equipment in this way shows a poor understanding of equipment management. When there are problems with the equipment, it is necessary to thoroughly check all possible issues, leaving none unexamined, including those that may arise in the process pipelines, before starting the equipment again; rather than starting it over and over again without such thorough checks.