Fire Pump current draw question

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bbaumer

bbaumer

Senior Member
Location
Indiana
Hi all.

I am planning on making some additions to a sprinkler system in an existing building with a fire pump. The pump is 30hp, 240V 3ph and is wired to a 240V 3ph source.

Nameplate FLC on the pump motor is 40A which jives with T430-250.

I asked for recent pump test results from the Owner. One year ago churn amps were about 38A, 100% flow amps about 55A and 150% flow amps about 75A.

The most recent test from Aug. 2009, showed churn amps at 102A, 100% flow 120A and 150% flow at 135A.

The testing company apparently said nothing to the Owner in the way of raising any red flags.

Any idea what might be going on here? Design flows (500gpm at 100% and 750gpm at 150%) were not quite reached but close.

Thanks.
 
Guess what bothers me the most is the company that did the functional test did not red flag the condition. Wondering if my thinking is off, that being this is an issue and needs addressed.

Oh - and I looked again at the rating. FLC on the motor is 72 at 240V, not 40. Also, looked at the wrong column on T250. It says 80A, not 40. I misread the nameplate and T250. Actual draw is still very high though.

The Owner's in-house staff is performing their own pump churn test tonight and will take amp readings and report back.
 
What is a "pump churn test"?
Is there any chance that they did not correctly measure the flow rate in the test with the high currents?
 
The first set of numbers seems what it should be, the second set of numbers is grossly higher than it should be. The great disparity smells of measurement error to me. If the pump is designed right, the 100% flow should be around 75% of FLA. So if the nameplate FLA is 72A, 55A at 100% flow is almost dead on for a conservative design. No flow amps are normally virtually meaningless, except in this case, a no-flow amp reading that exceeds the motor nameplate FLA is extremely suspicious. Your motor either has a SERIOUS mechanical problem, or someone doesn't know how to read a clam-on ammeter. My suspicion would be the latter, but due diligence says that you should check their work before having someone spend money checking the motor.
 
Jraef said:
The first set of numbers seems what it should be, the second set of numbers is grossly higher than it should be. The great disparity smells of measurement error to me. If the pump is designed right, the 100% flow should be around 75% of FLA. So if the nameplate FLA is 72A, 55A at 100% flow is almost dead on for a conservative design. No flow amps are normally virtually meaningless, except in this case, a no-flow amp reading that exceeds the motor nameplate FLA is extremely suspicious. Your motor either has a SERIOUS mechanical problem, or someone doesn't know how to read a clam-on ammeter. My suspicion would be the latter, but due diligence says that you should check their work before having someone spend money checking the motor.
Click to expand...

I think you are right. The Owner did a churn test last night. Roughly 38A. Not even close to the testing company's 102A!
 
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