power consumption vs size & freq. on a scroll type compressor

[iboomalot]

I noticed displacement and possibly pwr consumption on a scroll "could" vary depending on load or freq.


Is there a way to take a 1hp scroll and drop the freq from say 90hz to 50hz and thus use less power ??

I know the temps would go up some but when benching crank up the HZ and get more displacement for lower temps???

[andybg]

How are you going to go from 60 to 50? You have a frequency drive of some sort? If you only vary hertz from 60 to 50 without altering the voltage you will overheat the compressor most likely and cause winding damage.
If you drop hertz from 60 to 50 you will have to drop 115 VAC to 95 VAC to compensate. You may be able to find a 1HP VFD and play around with it to see.

I noticed displacement and possibly pwr consumption on a scroll "could" vary depending on load or freq.


It does vary somewhat and yes as your load changes you do see an increase and decrease in amp draw.

[chilly1]

IF you drop the frequency you will need to also lower the voltage a VFD ( variable frequency drive) is the best alternative. You could actually use a 1/3 hp Recriprocating compressor and when benching run teh Frequenct up to 75 for benching and down to 50 for operation under normal conditions. You will need to test a few compressors I know of only a few that are rated for this type of drive methods.

[iboomalot]

I thought I had read where the scrolls start out at low RPM like 20hz then spin up to 60 hz.

but ran across this PDF

http://kadenfan.hitachi.co.jp/comp/comp_e/comp_e14a.htm

EUSERIES(Scroll) Inverter Controlled Compressors

1. Small torque fluctuation, low vibration and quiet operation.
2. High efficiency due to high-precision process.
3. Wide rotation speed range.