Shocking Electrical question.

HHH Knives

HHH Knives

Super Moderator
Hello and good day Dogs! I was blessed to score a rather nice belt grinder with a 3HP 3phase 240V motor and now have to wire it up.

The plan is to add a VFD. and this off a 240 line. with the VFD for speed control. and I think it also will convert the 240 to 3phase?

My first question is. Can I run more then one machine in line on a 240 lead from my box?
Next would be what VFD and where to get it?

Any advise would be great. A electrician I am not so I appreciate any advise you guys with experience can give.

Blessings
Randy
 
IMHO it's not a good idea to run multiple 220v tools "inline"

What you can do is wire a plug onto the VFD. This way you can unplug the VFD and plug in say a welder or something else that is SINGLE phase 220v.

I did not do it this way and hard wired my VFD from the breaker so I can ONLY run 3 phase on that line.

I did wire a 220v dryer outlet on my VFD's output and currently run 6 different 3 phase tools from that single VFD. Just plug in what you want to run and you can ONLY run 1 tool at a time.

As far as VFD's go. You need to decide whether you want NEMA 4 rating or not. NEMA 4 is washdown rated so metallic dust is not a problem. NEMA 4 enclosure cost significantly more than non-NEMA 4

As knifemakers we skirt NEMA 4 by putting the VFD in a filtered enclosure. IIRC I had about $30 in my enclosure with automotive filters.

If you've got room in the breaker box it would be wise to power the VFD on a dedicated circuit IMHO.

NON NEMA 4-
http://www.factorymation.com/Products/FM50_230V/FM50-203-C.html

NEMA 4-
http://www.factorymation.com/Products/FM50_230V/FM50-203-N4FS.html

-Josh
 
Thanks for the info guys. I was hoping to add this tool inline with the welder. As you mentioned. But having it where both could run at same time. But if this is not possible, Then I will make the change and run a dedicated line in for this machine. Then still use the plug option so as I need to add a machine I can like you did Josh.

I will most likely go with the NEMA 4 rather then try to make a dust free box. Even with the cost difference.

Any and all other input is welcomed and appreciated.

Blessings
Randy
 
Sounds like you know where you're going.

I won't say it's impossible to run them inline. BUT the calculations for how much draw you're putting on that breaker are best left to a real electrician. Even with the proper calculating done I still wouldn't recommend doing it because the draw on an outlet will be determined by what is plugged in. Best to go dedicated IMHO.

What you don't want is the slow burn of drawing too many amps on that breaker and the resulting FIRE that would be a result. Pretty easy project to wire it all up yourself IF YOU GO WITH A DEDICATED CIRCUIT . Otherwise pay an electrician :)

Much easier for me being a one man show in my shop because I only need one tool at a time. It's very likely IMHO that you would be best served by installing a sub-panel to have dedicated lines for your tools. Even if you have to pay to have it installed. Better safe than burnt to the ground !

-Josh
 
I agree and that's why Im asking. I didn't think it was something I would be told is A-OK! I sorta expected to be told its not proper , yet I was not 100% sure and figured ill ask the pound!

I currently am maxed out on my box. So I will have to switch to a larger box as to accept the additional 220 line. Probably should of started with a larger board to begin with. Live and learn. I never would of thunk I would outgrow that box when I installed it!

God Bless YA!
Randy
 
I'm not an electrician, though I have an electrical background.

As far as running "in line", a 220VAC breaker spans both 120VAC legs of an electrical panel, so theoretically, it shouldn't make a difference (as far as power draw is concerned) if you are running two seperate 240VAC breakers, or "pig tailing" two outlets off of one breaker AS LONG as the breaker is rated at a combined capacity of both tools that will be running at the same time.

Granted, you should keep in mind what your "overload" protection may be reduced in the event of a surplus current to either machine. Your VFD will likely have built in protection, so it shouldn't be as much of a concern, but I'm not sure about your welder.

For example, if you're running a 25 amp welder on a 30 amp circuit, you are protected (via the circuit breaker) if you have a 5+amp surplus to the welder. Now, if you add a 3hp motor in line with that circuit (draws about 8 or 9 amps?) you'll want to increase to at least a 40 amp breaker in order to be able to run both machines at once. This means that it will take 10 more amps of "over current" to trip your breaker and protect your welder, or 30 more amps if just the VFD is running.

This also assumes that your conductors (wires) are rated for the potential full loads you'll see on this circuit. How big is your welder? What size wire are you running to the welders and its outlet?

All this being said, (assuming the overall circuit is up to spec) this probably won't be a problem in standard practice, but it is something to keep in mind.

Remember, a circuit is built for the load, and a breaker for the circuit. When you start splitting loads (I.E., running multiple machines at once) you are forced to rely less on the protection of the breaker panel, and more on any built in protection of the machines themselves (fuses, thermistors, internal breakers, etc...)

Clear as mud?

Somebody please correct me if I'm wrong or stated something incorrectly.
 
Another option you can think about:

If you have the room in your panel, you may be able to remove 4 normally sized single space breakers, and put those circuits on (2) 1/2 spaced breakers:

156513_300.jpg


That will then leave you with two empty spots to put an additional 240VAC double breaker in, which would allow you to keep everything on a seperate circuit.

Now, I wouldn't necessarily recommend doubling up your entire panel/sub-panel this way, but if you're just adding one more ~10 amp circuit, it really shouldn't be a problem at all.

I'd personally feel a little better about doing that than what I mentioned in my previous post.
 
I had to use a double breaker to get a 220v line myself. I only needed 1 because I had an open spot in the box still.

I'd put two doubles in without worrying about it but I'm with Andrew in that I would not load the box full of them.

I'd add a sub panel and rewire my shop in heartbeat if we weren't hoping to sell our place and move.

-Josh
 
when you add the 240 breaker, get one where both sides trip together; if one side trips, they both trip. you may also want to add a breaker/switch at your VFD, one with a lower number than the main in the box. It should trip before the main would and will save footsteps. the one I have can also be used as an on/off switch, so you can isolate power there if you need to do something to VFD wiring.
i also have a dedicated breaker that is only used for the VFD and a dedicated 110 breaker for tools.
 
Kb makes a vfd for 3 hp. Model 29 (1p) #10001. Max output is 9.0 amps. Reverse switch is #9480 and on off switch is # 9523. I bought this setup for my Baldor 3hp and everything runs well. The plus is that you will also be able to run less than 3hp motors as well. Hope this helps.
 
I sell a NEMA 4X VFD that uses 230v into the VFD and outputs to the motor 230v 3 phase. When you are operating more than one piece of equipment off of the VFD you should have all motors of the same hp and rpm. This is because inside the VFD you set a jumper for the hp of the motor you are running. Also you probably will set the J4 jumper to run the motor at double the rated speed. If you have done this and are running an 1800 rpm motor up to 3600 rpm, then plug into a 3600 rpm motor you can get a big surprise.

I can also supply the wiring kit which tells how to set up the VFD and wire the motor. The kit includes an 8' molded power cord, cable glands for a dust proof connection, 2' of 4 conductor cable for between the VFD and motor or you can purchase a longer cable, wire nuts and my wiring instructions.

Let me know if I can help you.
 
I have chosen to not run in the 2x mode. My motor is a 1750 rpm and I have a 6" drive wheel. I chosen a certain pulley ratio so that I woul get the belt speed that I felt was high enough for the belts that require this. Mine runs all out at about 5300 sfm. I would recommend designing around a desired drive wheel rpm, drive wheel size and desired sfpm, then everything else falls into place. That way you can run the vfd in non overdrive mode and then have or run other motors.
 
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