NEED HELP WITH FUSE PLACEMENT ON VFD

[Craig Daniel]

I bought a cheap vfd off ebay and have it wired and running but I was told I need an inline fuse for overload protection. Where would the fuse be placed in the circuit? I really appreciate all the help in advance.

 

[kuraki]

Ask the guy that told you that you needed one? I'm running 4 of the things in my shop and added no fuse protection to any of them.

 

[Lieblad]

For a VFD or any appliance, fuse or circuitbreaker needs to be in the supply circuit.(at the loadcenter).
Depending what type of circuit your VFD is connected to, you may not need additional protection.
Most guys treat their VFD & motor like any other plugged appliance. Relying on the OCPD of the circuit its plugged into.

But for example, if you connected a small VFD to a 240V 50A welder circuit, you should place additional OCPD suitable for the appliance (VFD & motor in this case) at the point of VFD connection.

 

[Craig Daniel]

The VFD is connected to 220 volt 30 amp double pole breaker, Should I connect the inline fuse where the 2 power leads wire in to the VFD? Also what size fuse do I need to install?

 

[kuraki]

That depends entirely on what size VFD you have and whether it's rated for 30a draw or not.

 

[Ken H>]

Craig, the breaker in the panel is to protect the wiring in the circuit from breaker to receptacle. Most of the folks here that are running VFDs simply plug into the circuit (either 120 or 220 VAC) and depend on the breaker to protect the wiring. That does NOT protect the VFD drive. "IF" you wish to add protective device to protect the VFD (I'll bet almost none of us have) you would add the additional fuse/breaker between the receptacle and VFD. You didn't say what size VFD you have, but I'd expect it to be less than 2hp rating? If so, the input will be perhaps 10 amps max (Don't remember exact current required).

Short story - don't worry about it.

 

[Craig Daniel]

Thanks so much for all the help guys, I ran the VFD today and am well pleased with it.

 

[Drew Riley]

Most VFDs now days have built in over current protection anyway (digital, not a fuse), though I think I do recall seeing a manual or two suggesting additional fuses on the incoming power for protection.
Most industrial MCCs will have in line fuses, or breakers closer to the ratings of the drives and other computers and such in them, but for our applications, this is overkill, IMO. As long as you have reliable connections and your area doesn’t have a lot of surges or power outages, you should be fine.

 

[Craig Daniel]

Thanks a lot, I have a lot of questions especially when it comes to electrical connections.