Motors running at low load

[casdar]

The case is a pump for an hydraulic power unit, the pump can operate at low load, so the pump only have to circulate oil until a nitrogen accumulator needs to increase its pressure, then the pump has to circulate the oil but to icnrease the pressure, so the pump is at full load.

The question is what could be the percentage of power consumption at a low load condition of a motor pump, and is there a standard for this issue?

 

[ScusaMe]

Pumps for hydraulic power units are typically of the Positive Displacement type. Since there are many different types of PD pumps, with the little information you have provided, it is impossible to "guess" an answer, and no, there is no rule of generality that would apply.

The electric motor is determined by the operating requirements of the pump. Therefore, you need to direct your inquiry at the manufacturer of your particular pump.

 

[electricpete]

Correct.

Also, trying to read between the lines of what the question MIGHT be.. the motor can safely supply any load level below full load: 10%...1%...the motor doesn't care. (If this is obvious our irrelevant to your question, I apologize )

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(2B)+(2B)' ?

 

[electricpete]

To add to my last post:
1-the motor supplies whatever power the load demands at the machine speed. In most cases for simplicity we can assume machine speed is constant (neglect slip)
2-I'm assuming fixed frequency supply.

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(2B)+(2B)' ?

 

[waross]

The question is what could be the percentage of power consumption at a low load condition of a motor pump, and is there a standard for this issue?

Stating your question this way can lead to misunderstanding and confusion.
Percentage of what? Full load? Efficiency?
A properly designed and applied pump will present a high load when pumping. The load may vary depending on the pressure differential across the pump.
When on bypass the pump will present less load. The power consumption will be the sum of the work done, the no-load losses and the load dependent losses. Pick any two parameters and calculate a percentage.

Bill
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"Why not the best?"
Jimmy Carter