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O_E
26-06-2008, 09:44 PM
Hi Everybody,

I want to learn two different types scroll compressors' max/min operartion frequency;

1-Copeland ZR28K3-PFJ-1 phase 220 V- 50 Hz compressor min and max operation frequency (Hz) ?

2-Copeland ZR28K3-TFD- 380 V- 3 phase-50 Hz compressor min and max operation frequency (Hz) ?

Thanks

Brian_UK
26-06-2008, 10:25 PM
Have you tried the Copeland website for this type of information?

O_E
26-06-2008, 11:44 PM
Yes I have, but I couldn't find this information. Thanks.

O_E
27-06-2008, 01:17 AM
Has anybody ever used this kind of compressor as variable speed? We could listen experiences about this.

Thanks.

GXMPLX
27-06-2008, 02:05 AM
Sorry, never done this, but as my wife says, I simply can't keep my mouth shut!

Copeland does not release this kind of information they will try to sell you the Digital Scroll.

The problen is not just a matter of frequency but voltage too.

The PFJ compressor works in 60Hz at 265V so I would asume it is safe to use it up to this condition but respecting this voltage too.

Notice that changing from 50Hz to 60Hz the amps remain more or less the same (within 5%) and the voltage changes proportional to the frequency 265/220=60/50 more or less.

The lower frequency is somewhat triky but I think it can be field measured.

The main problem when you go low (besides oil return, etc.) is that you have to cool the motor so I would set up an experiment trying to measure winding temperature.

Copeland's electrical handbook tells you how winding resistance varies with temperature.

I would not try to go to less than 33% of nominal system capacity in order not to have too much trouble with things like oil return, unless your system is designed for this.

For the TFD compressor the voltage frequency relation also holds (more or less) 460/380=60/50.

I suppose if you lower the frequency you should try to keep this same relation to the voltages.

Hope this is useful and I would love to hear about your results. Good luck!

WINJA
27-06-2008, 09:10 AM
Hi Everybody,

I want to learn two different types scroll compressors' max/min operartion frequency;

1-Copeland ZR28K3-PFJ-1 phase 220 V- 50 Hz compressor min and max operation frequency (Hz) ?

2-Copeland ZR28K3-TFD- 380 V- 3 phase-50 Hz compressor min and max operation frequency (Hz) ?

Thanks
I heard that its not just minimum and maximum frequency but also certain frequency has to be avoided due to harmonics causing expodential wear and damage , is this true or not ? anyone?

GXMPLX
27-06-2008, 02:47 PM
I heard that its not just minimum and maximum frequency but also certain frequency has to be avoided due to harmonics causing expodential wear and damage , is this true or not ? anyone?

The manufacturer´s never massified applications using frequency controllers (except in places like Japan I've heard) It must be for some reason! The expected life of a AC there is less than 5 years.

Resonance is always something to check for when varying frequency.

Every system has natural frequencies that will produce resonance. The problem here is that these frequencies depend on the load of the compressor, therefore you either need to have VERY good mathematical models to predict them or a lot of lab work to find them out!