use of temperature controller for non-temperature applications
use of temperature controller for non-temperature applications
(OP)
Hello friends, I have a temperature controller left over from a previous project and I want to put it to good use. I would like to use it as a constant pressure controller (on a water distribution pump). This is a 4-20 mA input/output model, so the input can seemingly be arbitrary. I can set the the 4 and 20 mA mappings during setup. The pressure transmitter, on its part, outputs 4-20 mA too. I plan to use PID mode to drive 4-20 mA controller output (sent to VFD) and use one of the alarms as an 'on' switch for the pump.
So is the only drawback I will encounter is the units painted on the box being C/F instead of bar/psi or am I missing something deeper?
So is the only drawback I will encounter is the units painted on the box being C/F instead of bar/psi or am I missing something deeper?





RE: use of temperature controller for non-temperature applications
Would seem to me that most VFDs can do all that by themselves. If you already have a sensor that puts out 4~20 then the VFD should be able to do everything. There's probably a parameter that can require the input to reach a certain level before the motor is commanded on.
Let us know how it works out!
Keith Cress
kcress - http://www.flaminsystems.com
RE: use of temperature controller for non-temperature applications
It was years ago, but a particular controller targeted for the plastics/packaging electric heat apps (a relatively slow response) and its proporational band setting maxed out 100 (gain = 1). It was installed in gas fired dryer with a massive burner, given the load size, with an incredibly fast response and its proportional band setting could not raised enough to slug down the response for stable control.
But I suspect that most modern controllers have very wide adjustment ranges and are not limited like that particular model was.
RE: use of temperature controller for non-temperature applications
TTFN (ta ta for now)
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RE: use of temperature controller for non-temperature applications
xnuke
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RE: use of temperature controller for non-temperature applications
The controller claims 150 ms/scan sampling rate for the 4-20 mA input, is that too slow?