Hello List,

Does anyone have any experience controlling PAT (Position Adjusting Type) motorized valve actuators with a PLC based control system. Any thoughts or comments are welcomed.

Bradley G. Hite
Intertech Incorporated
mailto:[email protected]
http://www.myplc.com
Teaching Practical Skills for a Technological World

 

A couple of things I have found that are often not thought of when driving valves that have simple motorized operators:

1) Use a control algorithm with adjustable setpoint deadband.

2) Include status inputs for full-close, and/or full-open, that can be set to stop the control outputs when the valve reaches its limit.

The reason for both of these is to prevent premature operator/motor failure from overdriving and nuisance operation.

 

I have used the bi-directional motor in several applications and wrote an article in Motion Control Magazine about improving its capabilities. The URL for the article is:

http://www.isa.org/journals/mc/feature/1,1773,8,00.html?index_userid=&first=
&last=

In that case, the control motor was used to position a butterfly valve which in turn fed a single burner for an oven. The temperature varied by +- 7 deg. F and the final product's density was changing more than the process
could handle. By correcting for the valve's deadband permitted process drift periodically, we improved the temperature control to less than 2 deg. F and made the product more consistent.

The article was from the September 1998 issue.

Regards,
Russ Kinner
AVCA Corporation
Maumee, OH USA