# Wiring up VFD ?



## mmcmdl (May 30, 2022)

So I have to wire the motor to 220 instead of 440 . I can do that . I have 4 wires coming in from the switch . I know the green is a ground . Does it matter which way the switch to the motor is wired ?? I'll get into the VFD a little later on tonight . This SES ( secret electrical $h** ) makes my head spin .


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## AGCB97 (May 30, 2022)

A little more info might help (at least it would help me help you)! If you're wiring 3-phase it will run regardless but if it turns backwards switch any 2 wires
Aaron


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## den-den (May 30, 2022)

"4 wires coming in from the switch"  is a red flag to me.  It is not a good idea to put a switch between the VFD and the motor.  Perhaps the switch is ahead of the VFD?  If so avoid using that switch for normal shut down.


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## rabler (May 30, 2022)

Dave,
4 wires coming in with one ground.  So you'll want to wire the other three directly to the VFD, and bypass the switch completely.  It really doesn't matter which wire goes to which of the main terminals on the VFD, except for which way (CW/CCW) forward/reverse spins.  You can switch any two wires between the VFD and motor to flip that between CW/CCW.  (Or you change the labels.)

Then you have to wire control switches to the VFD for on/off forward/reverse.  And program the VFD.


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## markba633csi (May 30, 2022)

VFD output must connect directly to motor, no switches or contactors in between
-Mark


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## graham-xrf (May 30, 2022)

As @rabler has mentioned, in three phase connections, swapping over any two results in motor reversal. The forward/reverse switch, in effect, is doing that for you. When you use a VFD, connect direct to the motor, without any switching in between, things can get very bad for the electronics unless it has the direct connection, because that is the only way it can sense the phase currents.  A VFD reverses the motor by electronically changing the relative phases, via software. Messing with this by allowing any intervening switches can result in damage.

You _can_ normally signal the VFD to start, stop, jog, reverse, etc. either from it's front panel buttons and software, or you can signal it's logic control inputs from external switches. Also, you can often use a interface to a PC with a controlling program.


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## mmcmdl (May 31, 2022)

OK , back at this after the bonfire last night . Series 1 , 2 horse BP . I have a forward / reverse switch on the left hand side of the head as usual . You're saying to wire the VFD in between this switch and the motor ? ( if you see smoke coming from my direction , lets hope it's from the firepit and not the BP )   So , in layman's terms . Breaker box to the forward / reverse switch , to the VFD ,to the motor pecker head ?


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## akjeff (May 31, 2022)

I would wire the single phase AC from some sort of disconnect device ( i.e. breaker, a simple appropriately rated on/off switch ) directly to the VFD input, and the VFD 3P out direct to the peckerhead. Repurpose the forward/reverse switch on the mill to act as contact closures to "tell" the VFD to run/stop and provide direction control.


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## jwmelvin (May 31, 2022)

Yes I agree with [mention]akjeff [/mention]


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