220v Wiring for grinder

H

h2ostx

Joined
Sep 3, 2004
Messages
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I just picked up a 220V variable speed setup for my KMG. I was just wondering if most everyone uses the standard 3 prong house plug, for like your clothes dryer?

I hadn't given it much thought until I started getting things ready for wiring it up.

Also, what size wire do you guys use for running to the controller, I will need an 8' cord. Do you recommend the flat 220v wire or something else.

Thanks for all the great information that everyone provides here.

Kelly
 
I just used regular three wire 12 guage bulk extension cord from the hardware store and put on a 220 vt plug. It looks just like a regular 110 vt plug but one prong is horizontal. The plugs for stoves and dryers are for very high amperage pull and not needed for a grinder motor. Just make sure the cable you get is rated for the motor's demands. Unless the idividual wires are smaller then 14 guage most cable will have a 300 vt rating. You don't want to try to wire a plug onto flat 3 con. cable. It is tough enough with braided wire.
 
Thanks, I'm definitely not an electrician.:confused:

I will wire it up like your describing, makes more sense. I did notice that the wires for dryers were rated at 30 amps but the motor was only 6.5 amps.

Thank you,

Kelly
 
You will need a two pole 20 amp breaker in ytou panel for the plug that you will be putting in. The receptical will be rated at 20 amps and constant use 220-250 volts. So you will want the proper 12 awg or even 10 awg wire if you want over kill from the plug to the breaker in the electrical panel. You can pick that stuff up at your local Home Depot or Lowes and it just looks and feels like oversized extension cord without ends. Your motor might only draw 6.5 amps at full load, but if for some reason the motor would lock up you want the breaker to pop before anything melts down and starts a fire.

Grew up with a father who is a master electrician and area electrical inspector. :)
 
You definitely want to run a dedicated 240v circuit to your work area.
I did just that, using 2 pole 20A breaker (HD, Lowes etc).

I use it for: electrical oven, TIG, MIG. Also, at some point :) I will replace
7A 120v "3/4" HP (Craftsman has a funny way to measure HP) motor in my bandsaw with true 1 1/2 HP motor from Grizz and will run it @ 240V

Use heaviest gage wire you can, at least 10awg - for the oven you WILL
get sooner or later .
 
The one leg vertical, the other horizontal is a 20 amp 220v plug/receptacle.
Both legs horizontal is 15amp, 220v plug/receptacle.

I use the 15 amp as it's still above the highest amp rating of the motor.

On the breaker, get close to the motor rating in amperage, because if you go way above in amperage and you have a short or some other electrical problem in the line, with maybe you involved:eek::eek:, it won't trip the breaker.

If it's closer to actual motor rating it will trip the breaker, maybe saving your motor, control and possibly you if you're in the middle of it all.:eek:;)
 
I just got in from Lowes and think I have what I need to make power happen. It's amazing, when you actually have an idea of what you need and fortunately I ran into an employee that knew exactly what I needed.

Now I can't wait to have this set up with variable speed. :cool:

THANKS for all your input.

Kelly
 
h2ostx said:
I just picked up a 220V variable speed setup for my KMG. I was just wondering if most everyone uses the standard 3 prong house plug, for like your clothes dryer?

I hadn't given it much thought until I started getting things ready for wiring it up.

Also, what size wire do you guys use for running to the controller, I will need an 8' cord. Do you recommend the flat 220v wire or something else.

Thanks for all the great information that everyone provides here.

Kelly
Click to expand...

Kelly

Being an electrical type I have a few comments and a couple questions.

If you are using a variable frequency AC drive, the output is most likely three phase? The input power, I am guessing is two phase? The way these units work is the input power goes to a DC power supply which in turn dirves three variable frequency generators that are phase locked to each other. When you change the speed setting you are changing the frequency of these generators. There is also current limiting circuits and other functions which I won't go into. Basically power into the motor is going to be (ignoring losses) the power going into the controller. Electrically speaking one horsepower is 746Watts, (assuming it is computed like it should be i.e. average not peak or maximum) Remember on a three phase motor the current is per phase for each of the three phases. The current for each of the input phases will be higher since it is only two phase. Just take the motor HP x 746 and divide by the input voltage to the controller (220VAC?) this should give you the input current to the controller. Size your wire based on this.

Jim A.:thumbup:

PS don't forget to run a ground wire to your motor if it is three phase and you use a three conductor wire to hook it to the controller.
 
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