Powerflex 4 field wiring question

TheDude_Abides

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• Mar 30, 2019

• #1

So i’m Field engineering a panel for a 19’ conveyor we are building. The conveyor will have 3 - powerflex 4 drives. My question is concerning the start input on the drive. Can I feed the output off the PLC (+24v) straight to the drive for the start input? If so do I need to take my power supply common to terminal 4? Right now the only way to get it to work is have my PLC output fire a 24vdc coil and run my drive +24vdc through a set of NO contacts. But I want to do away with all the relays that are unecessary if possible.

 

jstolaruk

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• Mar 30, 2019

• #2

Should work find, make sure the digital input SNK/SRC jumper is jumpered for SRC.

 

TheDude_Abides

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• Mar 30, 2019

• #3

So term 4 isn’t referencing the -24vdc in the drive itself, correct?

 

jstolaruk

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• Mar 30, 2019

• #4

Its called out as digital common.

 

jaden

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• Mar 30, 2019

• #5

The manual shows 2 wire control using an external supply.

 

rupej

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• Mar 30, 2019

• #6

Yup I do it all the time. Makes controlling drives much cleaner without relays all over the place.

 

TheDude_Abides

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• Mar 30, 2019

• #7

Awesome. That’s one thing I’m trying to accomplish with this panel. Only the necessary components, as streamlined as possible. Thank you all for the replies.

 

jraef

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• Apr 1, 2019

• #8

The argument for interposing relays is that if anything goes wrong in your control wiring, it takes out a cheap relay that can be easily replaced, not the more expensive VFD. You can’t repair the control board on the VFD.

 

TheDude_Abides

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• Apr 2, 2019

• #9

jraef said:

The argument for interposing relays is that if anything goes wrong in your control wiring, it takes out a cheap relay that can be easily replaced, not the more expensive VFD. You can’t repair the control board on the VFD.

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Yes, but it also makes troubleshooting twice as difficult and also adds a small amount of current for every relay you add. If all of your wiring for the VFD’s is integral to the cabinet then the chance of damage to the wiring itself is minimal. Also, a short on 24v system will reset the power supply. If I were running 120v controls then I would agree with you.