VFD control

i am looking to to install VFD speed control on six fan motors using a allen bradley PLC any pointers on how this project would be helpfull

More details on the equipment involved? What PLC? What VFD? What communication protocol?

vfd

Vfd svx9000
plc allen bradley

lennox1974 said:

Vfd svx9000
plc allen bradley

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OK. We're getting closer. what AB PLC? They're NOT all the same. I'm not familiar with svx9000. Who makes it?

Allen bradley 1756 rs logix 5000
cutler hammer make svx9000 vfd's

What coomunication interface?

At minimum, a VFD requires two control signals. One signal to tell it when to start, another to tell it how fast to go. Both of those signals can come from the PLC.

The run command is typically a contact closure. The speed command could be an analog signal. It could also be one or more contact closures which tell the VFD to select one of several preset speeds.

But, rereading your original post, I'm not sure I answered the question you asked. That's because I'm not sure what the question was. Do you want help on how to implement PLC control of a VFD or do you want reasons why PLC control of a VFD would be an improvement over the way the fan speed is currently controlled?

Cutler hammer has devicenet interfaces for its vfd, this is a nice option since you have 6 vfd.