View Full Version : How to figure FLA from RLA ?
06-01-2004, 09:12 AM
I know that you can run a freezer slightly over the RLA. How do you figure the FLA if you know the RLA.
Here's the situation. A tech went on a PM. The freezer was working fine for years. He checked a R/I freezer. The amperage was 2 amps over the nameplate RLA. So he adjusted the CPR valve to get the RLA down to the nameplate rating.
Now the freezer won't maintain temperature. The trick is now--how do we get it back to where it was? It should I assume be between the RLA and the FLA. We just have to figure out the FLA.
06-01-2004, 02:51 PM
RLA is Rated Load Amps, for fuse sizing and contactor selection - that's all - no other value
you need a curve sheet for the compressor
that shows amps under varying conditions
the RLA can often be 50% different than run amps
so is really not usefull (an old wifes tale)
sign in at http://www.copeland-corp.com and you can
get curves on their compressors
ditto at http://www.carlylecompreossor.com on Carlyle
if you have a Copeland compressor and can't get the
curve, give your email address and I'll email it
06-01-2004, 05:30 PM
This may help in understanding the difference between FLA, RLA and why we don't see FLA on compressors anymore:
As to the freezer running a bit higher than RLA, I'd check the measured amps against the manufacturer's performance curves at those conditions to see if there may not be a reason other than the CPR setting that the amps were high.
06-01-2004, 10:07 PM
Thank you men. This is exactly the information I was looking for.
refer dude 2479
06-01-2004, 10:38 PM
My guess is that if it worked fine before at or below nameplate and now it does not work and draws over nameplate you have a bad discharge valve. Get the compressor curves mentioned by the others and spec out the exact operating point of the compressor and compare to the curve. If amps are higher than the curve would indicate, bad discharge valves. If it is an old compressor change ti out. Open it up if it semihermetic.
Of course this assumes that condenser and fan are in good order.
06-01-2004, 11:48 PM
There may just be more to this scenario than what has been told to you thus far.
Sometimes a tech will not reveal every detail of their "adjustment" made while in the field.
Perhaps this tech also made other adjustments while there.
Maybe the charge is different now. Maybe the metering device has been tweeked.
Personally, I always prefer the open door policy to sharing what has been done, but after this one conversation I had tonight with another man in the company ... I can see that not everyone has the same views.
It appears there are some people whom you cannot share everything with.
They just cant handle it.
refer dude 2479
06-02-2004, 10:43 PM
Ain't that the truth. There as those that pick your brain while covering thier a** in an attempt to look good to the ones above
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