Motor Brake Horsepower (BHP) 2

[nightfox1925]

Is there any rule of the thumb or parameter estimation formula for estimating the mechanical loading of a given Pump, Fan or compressor HP rating for LV applications say 460VAC motors, 60Hz?

Whenever, there are existing motors where we are adding up new motor loads or when motor HP ratings are identified but without any given information on demand HP, what are best way to estimate the demand and associated power factor and efficiency?

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[davidbeach]

With no other information you can't do much other than assume fully loaded. If you start applying demand factors that aren't backed up with test data you will get bit at some point. If assuming fully loaded is going to cause problems then you need to get some measurements. A week with a recording ammeter in the absolute minimum, a month would be better.

 

[waross]

I have often found valuable demand information on past power invoices. Typically I request the last years power bills as a minimum, two years if available.
Also don't forget to look at the revenue meter. Many of the newer meters display the current demand as well as the maximum demand. (Don't forget the multiplier.) If the installation is not billed on demand, the demand indication may be the maximum from initial installation.
Another resource is the friendly local metering engineer. The metering department of one utility was kind enough to send out a technician with a laptop to down load the memory of an electronic revenue meter. He gave me a floppy disk with KVA, KW, volts per phase and amps per phase at 15 minute intervals for the last 6 weeks.
If you are not able to access these resources then you will probably have to go with the recording ammeter as David suggests.
respectfully

 

[nightfox1925]

Thanks gentlemen.

GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata