I would like to ask whether axial flow pumps in rainwater pumping stations generally use variable frequency control?
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I looked at the textbook's working condition adjustment methods for water pumps, including speed adjustment, diameter adjustment, angle adjustment, and throttling adjustment. So the axial flow pump should have variable angle adjustment itself, so will the actual application of axial flow pumps with large flow and small lift such as rainwater pumping stations require variable frequency adjustment? I always feel that the adjustment range of frequency conversion adjustment is limited. If the flow rate is too small, then the water pump will not work in the high efficiency zone at all. If the rainwater pumping station adopts frequency conversion, is it to meet the drainage requirements of small flow or to reduce the impact of the current on the initial startup of the axial flow pump?
Personally, I think it would be nice to have an adjustment method. If you have to do everything, there will be problems of mutual restraint, which is not conducive to the normal operation of the pump and shortens the service life of the pump.
Variable speed saves energy.: The energy consumed by pipeline resistance cannot be saved by static pressure head. If the flow rate changes greatly, a variable speed motor can also be considered, but you need to look at the "limit" relationship between the flow range and the speed. The speed range corresponding to the demand flow range is too small, which is unfavorable for control.
I don't understand how complicated a rainwater pump is. First of all, there should be a puddle in front of the rainwater pump, and a liquid level switch should be set according to the liquid level of the puddle. The pump automatically starts when the liquid level is high, and stops automatically when the liquid level is low. I don’t understand why frequency conversion is needed? Is it because the puddle is too small?
Rainwater pumps should not have such requirements
Frequency conversion only reduces the starting current when starting, and then it is the power frequency.