Centrifugal water pump current problem?
Thread Content
The water pump is a single-stage double-suction centrifugal pump. When stopping the pump, the water pump interlock is used to stop the pump after closing the outlet valve. When only this water pump is running, 4 to 5 seconds after closing the pump outlet door (butterfly valve), the motor current begins to rise and the flow pressure also drops. The current rises to the maximum when it is about half closed, and the pump stops when the valve is fully closed. The historical graph is shown above. The flow meter and pressure gauge are both on the main pipe, which is a main pipe method in which multiple water pumps are connected in parallel. This is the case when several water pumps are stopped during individual trial runs. The flow meter is not accurate when estimating that the pipe is not full, but the current changes are not understood. There is a doubt: 1. Since it is a centrifugal pump, after closing the outlet door, the water volume at the pump outlet decreases. Why does the current increase? 2. Since the valve is closed, the flow rate should gradually decrease. As shown in the figure, the flow rate is the lowest when the current is maximum but then increases?
This performance does not belong to a centrifugal pump, but to a mixed-flow pump. The power-flow curve is the highest when it is closed, so the increase in current is reasonable.
If it is as mentioned on the second floor, it is not appropriate to shut down the pump valve and interlock the pump. Can the poster post the nameplate of the pump, so that everyone can learn from it?
You should first check whether the pump is running when this happens. If it is still running after stopping the pump, it may be that the outlet butterfly valve is leaking, the equipment is reversed, and the butterfly valve itself is not tightly sealed.
I have never seen a double-suction mixed-flow pump. Will this pump have a hump in its flow-lift curve?
This post was last edited by Polar Wind on 2018-12-22 20:47 Single-stage double-suction water bottle split centrifugal pump
The specific speed of 260 is a high specific speed centrifugal pump.
I don’t understand this. Is it related to the historical trend of rising valve closing current? Thank you!
This post was last posted by Bubble_ZPTK edited on 2018-12-19 22:07 to find the test data of this pump. There is (random data) in the completion data. See if the head of the pump first decreases and then increases and then decreases when the flow rate of the pump increases from zero flow rate. If so, it means that the curve has a hump.
This information should not be available. During debugging, the water pump was simply tested for vibration, bearing temperature, stator temperature, etc. The flow meter is on the main pipe after the outlet valve of the pump, and it seems to be a vortex flow meter. When the valve is almost completely closed, the current rises to the rated current value. If there is a hump, it is better to stop the pump first and then interlock to close the valve!
Which model of water pump has a hump? How can this situation be avoided? Thank you!