Variable frequency Drives and pumps
Variable frequency Drives and pumps
(OP)
We recently had to change an electric motor (2 pole ,2900 rpm,5 kw) operating at 30 hz through a variable frequency drive.
We replaced it for a 4 pole,1450 rpm and changed the frequency to 60 hz because we had no spare 2 pole motor.
My boss and our plant electrician are currently arguing over this installation.
My boss says it will run better, more efficiently and consume less amps for a given load compared with the original set up using a 2 pole.
The electrician says it will make no difference.
Can anyone tell me who is correct and what is the theory behind your answers.
The motor and pump have been operating now for around 2 days with no problems.
We replaced it for a 4 pole,1450 rpm and changed the frequency to 60 hz because we had no spare 2 pole motor.
My boss and our plant electrician are currently arguing over this installation.
My boss says it will run better, more efficiently and consume less amps for a given load compared with the original set up using a 2 pole.
The electrician says it will make no difference.
Can anyone tell me who is correct and what is the theory behind your answers.
The motor and pump have been operating now for around 2 days with no problems.





RE: Variable frequency Drives and pumps
RE: Variable frequency Drives and pumps
The problem, I believe, is that a motor operating at low frequency has more difficulty cooling itself and therefore needs to be designed/manufactured accordingly.
RE: Variable frequency Drives and pumps
I changed 1450 rpm 4 kW motor to 2990 4 kW motor, but it took overcurrent all the time at the same flows (waterpump) so I had to change old motor back.
I guess that your boss is right.
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