Dear all,
we have a 75kW pump submersible pump with Star-Delta control. It came to my notice recently that the starting current of one of the pumps is 21A (others that we have typically have a starting current of 160A) while the running current is 55A (as against 70A for the others). The speed of the pump is also lower than that of the other pumps.

Does anyone have any ideas as to what the problem may be? Previous experience and how the problem was solved?Your support will be most appreciated.

Truly, I have not experienced this kind of situation before.

Regards,
VMAC100

looks like the impeller is not being driven by the shaft or is there a diffuser in which case it's worn out.

some 15 years ago when I was still starting up, we had cooling water circulating pumps for the turbine condensors. they had a diffusor which due to cavitation/erosion used to wear out and eventually cut in two and the lower part falling down. we could notice this by monitoring the current drawn.

Thanks Rennie.

However, the pump evavuates the water as so I would say that the impeller is being driven by the shaft.

When you say 'diffuser', what do you mean?

Grateful

Hello,

It's difficult for me to explain, english not being my mother language. It's like a curved surface (housing) to direct the water into the impeller.

Vmac,

So you have lower starting & running currents? This is quite strange. Normally people use soft starter to reduce starting current but your problem is the reverse.

Read here about what is a pump diffuser:
http://www.engineersedge.com/pumps/diffuser.htm

Rennie, did you mean the diffuser vanes got worn out and their lower halves broken off or detached from the impeller?

Vmac, even though the pump still evacuates water, is it at the right discharge pressure & flow rate?

This message has been edited. Last edited by: Josh,

What is the nameplate speed rating and what speed is the machine actually running?

What is the distance from the power supply to the pump?

What is the cable (wire) size?

What is the voltage at the power supply, itself?

What is the nameplate voltage and current for the pump?

Howard