We recently overhauled a multi-stage pump. We changed the impellers and when we commissioned back the pump, the motor trips due to high amp. Actual design pressure is 400 psi and the motor amps is 50 and the full flow is 3.3 Kbd. We commissioned the pump, the discharge pressure is 390 psi and motor amp is 55 and the flow is 1.7 Kbd. When the flow reaches 1.8 Kbd, the motor amps reaches 60 amps and pump trips off. We did a solo run of the motor and the amp is 15 at no load, and the pump shaft also can rotate freely. What is going on?
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Ross Mackay Forum Moderator 94 Posts
Re: Why is our pump operating at a lower pressure and drawing higher amps?14 May 2012 at 1:29pmWhen a pump operates at a lower pressure and draws higher amps, it usually means it's running further out on the curve. If this continues to a higher flow, then the motor will naturally trip out if size does not cover the run out condition of the pump. It is possible that the new impellers are larger or different hydraulic than the older ones. Unfortunately, you don't provide enough information to be absolutely certain.