Open Drive Compressor

[tech_support007]

Has anyone ever heard of hooking up a Open Drive compressor with a Variable speed motor? If so what are the thinks that need to be taken into consideration? I know that the oil pressure needs maintain a proper operating pressures.

[seabee5701]

I do not have recent experience with a modern open drive compressor but...I worked in a very large plant with 6 units that were 3000 tons each,trane,york and the 3rd type was worthington..from what I recall,there were separate oil pump motors,small independent of the chiller compressors....so if it is like this then it might not be a problem.....but they were very large motors driving the compressors..

[freonrick]

I would contact the compressor factory and find out what they say. they should be able to tell you rpm range and any thing else.

[techhead]

Have done it with carriers worked great just make sure your low rpm is within the spec of the compressor.
we ran suction temp sensor to control speed.

you did mean a Vfd?

[wolfdog]

I worked on a custom packaged unit for grocery stores that used a Carried open drive with a variable pitch pulley like the Trane Varitrac. The hydraulic unloaders were adjusted way high and the energy management software for the store handled the position of the pulley.

I can't give any details but Tom Thumb was putting them on their stores so it can be done.

[RichardL]

Each manufacturer has it's own "Minimum" speed, for it's open drive Recip's. Carrier, York, Snacke etc. that are belt driven, all are slightly below 1/2 direct coupled speed.Example(York=740 RPM min)
It would be without a doubt the best capacity control method out there. But do "Not" expect any manufacturer to give it's blessings on this..
Should you attempt this, absolutely & positively remove any other cylinder unloading first....otherwise thou' will be creeping around in the 5% capacity region & oil return will be zip...nada'.....nary' none....
I played with this on some Delta Airlines "Air-A-Plane" units with a 460 Ford & 8 cyl. Trane E compressor....They used on older planes without an APU onboard.(Convair 880)
Them "E" compressors will hump out some cooling when you spin them up to about 3000RPM...

[stanbyyourword]

seen them on ice rink packs w open drive vilters superb control of unloading and pressure control, as stated follow manuf minimum and maximum limits stan