Non overloading power V.S Runout power

[sunloco]

Anyone can give a specific explanation for this two glossary in the pump curve, in my view I think the same meaning sometimes. but in certain curve data it will mark non overloading power at certain capacity ,not maximum capacity of rated impeller diameter. that's confused.

 

[BigInch]

Runout power is the power required to pump some indicated flowrate at the corresponding differential pressure as shown on your pump curve, which is typically well above the maximum power rating of your motor driver.

A typical maximum power rating of a pump motor might be approximately 20 to 30% higher than the power required by the pump when operating at the Best Efficiency Point (BEP). Depending on the actual pump, runout power values may be in the range of 50 to 75% higher (or more) than your motor's capability. If you enter the overload flowrate range, motor burnout will follow.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[sunloco]

Sorry , I is still in confusion. where do we get non-oveloading power from pump curve normally ? not the runout piont ? as I know, non-overloading point is not same as runout point . pls help clarify .

 

[Artisi]

I would agree that NOL power and run out power are confusing terms and are best avoided, however they are used and you need to review the term each time it is used.

So my thoughts as an explanation - not all pumps behave the same at the far right hand end of their curve.

On some units the power input starts to droop as you reach the far right hand side of the curve - therefore you can nominate a NOL power(particular motor selection) for the pump which the pump cannot exceed. On other units the power curve shows an ever increasing rise - therefore you need to nominate a power (runout power)which will be sufficient to cover any point of operation beyond its selected duty point as it "runs out" along its curve.
Runout power is an informed decision following a study of the pump system - it can be based on NPSHr, total head across the pump or a control system that will monitor potential over load or over capacity. "Runout" power to my thinking does not ensure NOL operation.



Naresuan University
Phitsanulok
Thailand