2 replies to this topic

[xyz168]

What is the relationship between the flow rate and amp usage on compressor? In other word, how is the amp usage affected if we lower the ACFM? I've been looking around but it seems like there is no formula that best describe this relationship. It really seems pump curve is the best bet.

PS: I am referring to both PD and centrifugal.

Thanks.

[Art Montemayor]

Just what exactly - and specifically - are you trying to do, apply, or achieve with the relationship you are looking for? Please be specific and don't just say you want to describe the relationship. We are all engineers here, and not pure scientists. We look for specific, quantified answers and solutions - not qualitative effects.

I think I know what you are alluding to, but I want to make sure so I don't waste my time going off on a tangent. ALL COMPRESSORS - and that includes positive displacement reciprocating types as well as dynamic centrifugals - consume electric power when connected to an electric motor driver. We all know that. We should also know that as the work done is increased, the power consumed will also increase. THAT is a definite "relationship". I think you want more than just that type of "relationship". I think you want an "equation" that translates the gas flow rate compressed to an amperage draw from an electric main feed.

Any centrifugal pump performance curve will give you that relationship in the form of separate curves. This is not normally done with compressors because the so-called relationship is almost always really of no value - in a practical application. So, why you would want to have that equation(s) is something that I'm curious about.

Await your response.

[xyz168]

Art:

Sorry for being vague. You are absolutely right. I am trying to find an equation that translates the gas flow rate compressed to an amperate draw from an electric main feed.

I am trying to compare unit operating cost at different charge rate. Energy usage is one of the components. I would like to know how much electricity we save by having the compressors not operating at its rated capacity. Based on your previous email, I assume there is not much electric savings for compressors when it's not running at the rated capacity?

Thanks.