Electrical In Front Of A Vfd, Between The Vfd And Motor?

[itsme_Bernie]

No magnetic switches between the VFD and motor. A three position switch is fine, just don't switch it while it is running or even turning.
I have my VFD hanging on a hook next to whatever machine I am using. I use twist lock connectors so I won't blow it. No enclosure for 10 years now, no problems.

Bernie

 

[JimDawson]

Hmmm but isn't that what the Forward/Reverse switch is doing? Its a 3 position switch, forward, stop, reverse. I'm fine with no contactor there I'm just curious.

I'm a little late getting back to the party. Well that seem like that is exactly what the switch is doing, unconventional at best. I have never seen that done before, and it goes against every VFD manufacture's recommendations that I have ever read.

Here is a simple schematic for the power contactor circuit. If you don't have a neutral on your plug, this could be wired across the 240V line with a 240V coil relay. The Automation Direct relay part number shown is a 120V coil.

 

[JimDawson]

DISCLAIMER: I have never switched the power between a VFD and motor, not wanting to brick a $250 VFD. So it is possible that the VFD won't fault on FLA if you start it that way (maybe there is a time delay). The enemy of transistors is heat; current passing through the transistor generates heat. However, short durations starting surge might not heat it up enough to fry a transistor. I don't know, and I am not curious enough to risk $250 to find out.

I agree, maybe some day I'll have a spare to try that with. I'm curious as to what would happen.

 

[wrmiller]

My Danfoss control panel is located next to the DRO. It was on the head but I don't like electronics getting abused like that.

 

[coolidge]

Bill I'm replacing that Danfoss 10k pot. Its rather pathetic imo, it only has about 180 degrees of rotation, zero resistance to turning, and the knob is tiny. I found trying to adjust the speed pretty annoying. I'm not going multi-turn or anything but at least a single turn 270 degrees. And ideally I would put that control panel back on the main unit vs having it remote mounted out front.

 

[tmarks11]

I agree, maybe some day I'll have a spare to try that with. I'm curious as to what would happen.

It should just fault on exceeding FLA limits, not fry a transistor. But since it is just as easy to hook up the VFD the right way (instead of the wrong way), it never really seemed worth experimenting to find out,