Reasons for reverse current during operation of cantilever centrifugal pumps
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A certain DMC unit is equipped with a hot water pump that supplies water at 50°C. When the pump was tested with the outlet valve fully open, the flow rate decreased by 30%, the outlet pressure remained acceptable, but the pump operated at excessive current levels. After analysis, it was found that the pump was running in reverse. It is understandable that a centrifugal pump running in reverse cannot generate pressure or deliver flow; the pumps that ran in reverse in previous instances also did not experience overcurrent. Then why does overcurrent occur when the pump runs in reverse?
The reasons for excessive current when a centrifugal pump operates in reverse may include the following: 1. Low flow rate leading to high current: Generally, the flow rate of a centrifugal pump is proportional to the current. When the pump’s flow rate decreases, the load on the motor increases, which in turn results in a higher current. 2. Impeller wear: Wear of the impeller in a centrifugal pump increases the load on the motor, which leads to excessive current when it reverses direction. 3. Motor issues: When a centrifugal pump operates in reverse, a large reverse torque can be generated; if the motor’s insulation quality is poor, this may lead to excessive current flow. 4. Control system issues: If there are problems with the control system of the centrifugal pump, it may lead to excessive current when the pump operates in reverse. The above four situations require analysis on a case-by-case basis. Such as checking the insulation performance of the motor, whether the impeller is worn, and whether the control system is functioning properly. Safety must be considered during the inspection to ensure the proper operation of the equipment. .