1000 Ton CHiller with VSD... 2

[sher210]

I was wondering if anyone else has had any problems with a York Chiller after adding a VSD onto it. Around 6 or 7 years ago, the unit was entirely rebuilt and had a VSD added onto it to increase the units efficiency. Before this, the Chiller ran fine without any problems, however ever since the VSD was installed it's had multiple oil pump failures, some electrical issues, and parts (example being the thrust bearing) seem to be wearing much faster then originally expected.

Has anyone else had any similar problems? or is this just a freak incident? Maintence issues may also be a possibility...but I want to assume that isn't it for the time being. Any sort of ideas or suggestions would be helpful. Thanks.

 

[absrbrtek]

I have seen this before on a VFD retro. 2 oil pumps (not variable speed), 1 motor (the new 460v motor), multiple boards and electronics failures. Took the manufacturer just about 2 years to get it right. Had the 50 Hz flashcard in it instead of the 60 Hz. Finaly ran for about 4 months this year and ground the high speed thrust down till it finaly locked out on a proximity failure.

This was a 4160V unit in which they added a 4160/460v transformer. An older 1000 ton YK running on R22.

 

[Yorkman]

You did'nt say was this machine a YK high pressure? I assume so. One issue to look at is as the load drops on the machine and the VSD slows motor RPM down the condenser water temps. need to be lowered also so that stall and surging can be avoided. Excess suging can lead to premature thrust bearing failures. As far as oil pump failues I'm not sure I would associate those to the VSD on the compressor motor. Is there a VSD fit on the oil pump as well if this is a YK I would think so. York has changed motors and boards on thier newer YKs, the factory hasn't really said as to why the change.
Most of the drives I've seen coming out of the factory seem to be performing quite well. A few have had drive/electonic issues, but all were covered under warrenty.
The biggest concern is the surging brought about by running at reduced load and trying to maintain 75-80 degree condenser water, that needs to be dropped to 60-65 degrees at least.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[EmeraldCoastHVACR]

The whole system should be VSD with a coherent control system.

I'm hoping the pumps(very important) and fans in the AHUs are variable speed too