[South Florida DX Association] AC starting loads

[NPAlex at aol.com]

In a message dated 4/8/2005 10:19:51 PM Eastern Daylight Time, 
n8pr at bellsouth.net writes:

Do you know of anyone in the club that is an electrical engineer or 
electrician? I am trying to get a solid opinion on whether my 15kw generator 
will start up my 4ton A/C. I have spoken to both the generator and A/C 
manufacturers and none will give me a quality answer. I was hoping I could 
have someone come and take accurate peak amperage readings and running 
amperage readings on my A/C unit. Alternatively I can rent a 15kw gas 
generator, but will need an electrician to hook it up for me temporarily to 
see if it will work.

Thx
André Venter , N1AJV
=================================
Pete,
The problem ought to be just numbers that is volts x amps (VA).
If Andre can get a "clamp on" VA meter he can see the peak start current, or 
some approximations can be made that will put you in the ball park.
1 ton of refrigeration = 3.42 KW 
4ton = 13.68 KW  or 13.68 VA and at 100% efficiency that would be 13680/240 = 
57 amps, assume the starting load to be at least 50% more that results in a 
peak current load of 85.5 amps.

The Generac 15kw generator has a peak load rating of 18kw, or at 240 volts 
that would be 75amps.  This would indicate it is in the realm of possible, but 
marginal enough that it is necessary to measure that peak start current with a 
meter.  One other problem with AC units is these starting currents can vary 
considerably depending on the compressor condition, and gas pressures.


Regards,
Norm W4QN