Vfd for well pump

[Ganelmatt]

Hey guys just wondering if anyone has ever built a VFD for a well pump using a pressure transmitter and a Allen Bradley drive. Maybe this isn’t even possible. Just curious. Thanks

 

[Bobster]

This is a bog standard design, depends on what you want the pressure transmitter to control.

 

[Spoon]

As above. Isn't it just a case of the transmitter being an input for the Allen Bradley PLC and an output being the 'Start' signal for the VFD?
Or do you want different controls?

 

[Spoon]

@Rob, you are up early mate...

 

[Bobster]

@Rob, you are up early mate...

I'm not in the UK timezone.

The OP dependent on what he wants to do, could connect the sensor direct to the drive without the need of a PLC and use the drives inbuilt PID or basic logic functions.

It's a really common set up for pumping systems/LEV systems.

 

[Spoon]

I'm not in the UK timezone.

The OP dependent on what he wants to do, could connect the sensor direct to the drive without the need of a PLC and use the drives inbuilt PID or basic logic functions.

It's a really common set up for pumping systems/LEV systems.

True mate. That's why I asked if he wanted different controls

 

[Ganelmatt]

This is a bog standard design, depends on what you want the pressure transmitter to control.

Just to keep the pressure at 60 psi

 

[Spoon]

Just to keep the pressure at 60 psi

What VFD are you thinking of using?
As above, why not feed the signal from the sensor directly into the drive? Why the Allen Bradley PLC?

 

[Bobster]

Just to keep the pressure at 60 psi

Easy, just get a VFD with an analog input that matches the output from your pressure transmitter, and that is capable of built in PID control.

How big a drive are you planning on using kW wise?

The Powerflex 7xx seiries would have all the capability. However, if it is a small VFD it may be cheaper to use a small programmable relay to run the PID loop.

 

[Bobster]

Just noticed you're a plumber.

This is a simple job, but above even a "standard electrician"

You'll also have to take into account your local codes. An the system will most likely, dependent on where you are in Canada be (UL) C-UL compliant

 

[Spoon]

Just out of interest @Ganelmatt can you tell us more about what you need this for. I'm just curious as if this is something you are designing then you may have over engineered it a bit.
I'm presuming the VFD is cause the motor is 3 phase and you only have single phase? I can't see a need for variable speed of the motor.
Is the motor existing or are you purchasing one?

 

[Ganelmatt]

What VFD are you thinking of using?
As above, why not feed the signal from the sensor directly into the drive? Why the Allen Bradley PLC?

It’s a Allen bradly drive I have, just wasn’t sure if there’s setting in the drive to say run and keep the pressure sensor reading 60

 

[Spoon]

It’s a Allen bradly drive I have, just wasn’t sure if there’s setting in the drive to say run and keep the pressure sensor reading 60

That makes it more clear. The VFD is Allen Bradley and there is no PLC.

 

[Ganelmatt]

That makes it more clear. The VFD is Allen Bradley and there is no PLC.

No there is no plc

 

[Spoon]

So tell us what you are trying to do, in more detail.
Why are you using a VFD?
Is the pump motor an existing motor?