VFD Compressor Minimum Speeds

Return to Engineering Main Menu

Email from Clay Brown on 1/2/20

Subject: VFD_Minimum Speed Update

See the below table for minimum speed setting for the ZPV variable speed compressors. These minimums are expressed as a percentage of the design RPM used for the VBalance selection. These minimum speeds have been selected to maintain a minimum velocity in the suction lines for better oil return.

We need to make sure that we are setting the minimum speed for ALL ZPV compressors per the table below. The ZPV066 and ZPV096 have a different minimum at 3600 RPM because we are using a smaller suction line size on these models. We also need to make sure that these minimums are properly communicated to the ATC for controls by others projects.

 

		MINIMUM SPEED (%)
DESIGN RPM		ZPV063	ZPV066	ZPV096
	3600	68%	50%	50%
	4200	58%	58%	58%
	4800	50%	50%	50%
	5400	45%	45%	45%
	6000	40%	40%	40%
	6600	38%	38%	38%
	7200	35%	35%	35%

 

 

 

 

 

 

Controller Setup Info

Email from Jack Murray (12/26/19)

There has been a slight change in the Minimum Speed settings for the Copeland ZPVs (variable speed scroll compressors). This minimum cannot be set in the Emerson drives, therefore we must set it in the controls software using the chart in the email below.

Use the attached instructions document to set the minimum speed via Bacview or Equipment Touch for jobs that have already been shipped. If this is a Controls by Others job, we must include the minimum speed in the sequence.