consumption vs FLA vs motor hp

[mech4321]

Hi,

We have to evaluate the power consumption of a fluid cooler which have at 600V an FLA of 23A. That would give approximately kw = 600 x 23 x 1.73 = 23.9 kw or 32 hp. However, the fluid cooler has only a total of motor of 6 x 1.5 hp = 9 hp (plus a small amount for the controls). Where does come this big differance? How can we evaluate the consumption at full load if this value is not available from the manufacturer.

Thanks
Alex

 

[MintJulep]

Use an ampmeter.

 

[berkshire]

You are neglecting the fact that the full load amperage ( starting load) is about double the running amperage.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[mech4321]

I tought that the starting load is related to the LRA (locked rotor amperage) which can be estimated to 5 to 6 times the FLA?
Alex

 

[ScottyUK]

Full load current is declared at nominal voltage under maximum power output conditions. Full load current is not the same as starting current.

Are you sure there are no other loads on the unit, and that there really are six 1.5HP motors? If it is a chiller they typically have relatively large compressor motor with a couple of relatively small fans associated with it. Some units have multiple banks of compressor + fans on a common frame. It is unusual to see a chiller where the compressor motor is the same size as the fans, although perhaps not impossible.

Are there any significant single phase loads such as heaters which would force the current to be high on one phase but would require the 3-phase service to be sized to suit, i.e. one phase draws 23A but two phases are only part-loaded?

 

[DRWeig]

alupien,

You already have a thread going with this exact same question in another forum -- Electric Motors, Generators, and Control Engineering. People are still posting there, as well as here, which gets very confusing.

Please take a few moments to read the forum policies, especially number 4. There is a link to them below my name.

For the rest of us, here is a link to the other thread:

http://www.eng-tips.com/viewthread.cfm?qid=329873

Best to you,

Goober Dave

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