PowerFlex 4 to vary pump output pressure

[jonmoga]

Hello,

I have a glyco system that chills several product tanks. We have a problem with over presurizing the glycol system when only a few tanks are on. I'm hoping to vary the speed of the pump using a AB Powerflex4 and a presure transmiting using the 4-20ma to control the speed.

Here's my questions.

How do I configure the VFD to vary the motor from an inverse 4-20ma signal, ie pressue is high(20ma) slow the motor down, pressure is low(4ma) speed motor up.
How do I configure it to hold at a desired setpoint, say I want the system to run at 18psi or 9.75ma whether the is 1 tank chilling or 12 tanks.
With more tanks chilling it will require a high pump speed to maintain the desired pressure and vice versa.
Is the powerflex able to do that kind of scaling?

Thanks

Jon

 

[Stig]

Correct me if I'm wrong guys, but according to my magic PF4 book: A112 and A113 is your scaling, set A112 to 100%, A113 to 0% to reverse scale. A112 is the low side of 4-20, and A113 is the high side.

 

[jonmoga]

Good I am on the right track. My big question is how to program it to hold at a derised analog input signal?

 

[Stig]

That part has me, have not had to maintain fluid pressure on that scale...yet that is. I am curious as well on this.

 

[Cow]

I would say you should be using a PF400 for this, rather than a general duty PF4.

 

[alan_505]

Better still use a PF525

 

[jonmoga]

The PF 400 looks like it is perfect for my application and they have been ordered! Thx for the help!