I would like some advice on the issue of the rotary jet pump not starting
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The impeller and casing of the jet pump rotate together; its starting inertia is relatively high. A 22kW motor is used, and the starting current is around 5 times the rated current of 40A, namely over 200A. The start-up time is 8 seconds, the pressure rises slowly, and it seems that the rotational speed does not increase either. Then it shuts down due to a startup time timeout. Adjusted to 15 seconds, the pressure also rises slowly to 1.5 MPa, which is still below the rated head. Parking after the time limit. Could the experts please analyze what’s going on? Was the motor size too small?
Is the Qidong method soft-start, variable-frequency start, or direct start? What is the rated head? Normal pumps never operate at their rated head.
Looking at the set start time, I’ve seen that self-ventilated reduced-pressure starting requires a start time to be set – is it self-ventilated reduced-pressure starting?
For ordinary centrifugal pumps, the operating time generally should not exceed 8 seconds; the rated head is 285 m, the density is 0.9, and the pump is started without the use of variable frequency or soft start technology
It hasn’t started yet after 8 seconds of attempting to launch it; it still doesn’t start even after 15 seconds
Please have the original manufacturer reply – why do we have to keep asking around?
There should be a random instruction manual for the pump, along with operating procedures; if there are any issues, you can directly consult the manufacturer’s after-sales staff
To determine whether to choose a smaller motor, just check the shaft power
Is there an opening at the pump’s inlet? Would reducing that opening help, or should we try running the motor alone first?
Centrifugal pumps can also encounter this problem; before starting the pump, open the outlet valve slightly to minimize the work required during startup, and then gradually open the outlet valve after the pump has started running