[polyn]

I'm new to the group. We just received our first CNC machine last week. It's used but I saw it run at the sellers location and then had it shipped to the manufacturer where we did training on it.The three phase power in our shop is a high leg delta system. This means leg 2 is 208 volts to the ground. Legs 1 and 2 are 120 volts to ground. leg to leg is 240 volts.
We wired the machine as the manufacturer told us, knowing we had this type of power. The K1 breaker inside the control panel that runs the computer trips when we turn the control panel switch on.
Any ideas? I'm worried we fried the machine. Fingers crossed that didn't happen it was a huge investment for our small business.
Thanks!!

[want-to-be-cnc]

Hello Polyn,

Your system is called an open Delta. I'm not sure what breaker K-1 is but I'm guessing it is for 120 V controls. If you have that circuit connected to the 208v leg I can see the breaker tripping. What's happening is you're getting 208v instead of 120v. There should be a neutral(white) that goes into machine. Between that white wire and either phase 1 or 3 you should get 120 V. If for some reason after reason relocating it the spindle runs backwards you will need to swap phase 1 and 3 just remember you don't want the high leg on that K-1 breaker. It's possible that you fried something, but hopefully not.(You can always give it the smell test) When you give it another try, leave the K-1 breaker off. Turn on the power, and then measure the voltage coming in to that breaker, and make sure you have 120V to ground/neutral.

Hope this helps.
Larry

PS if I knew as much about CNC as I do electrical systems be doing pretty good, but that's why I'm here learning is much as I can.

[RCaffin]

Infinitely better solution: Get rid of that High Leg Delta supply!

Get onto the local power supply people and DEMAND a genuine 3-phase supply. They will ***** and moan about the cost. But you will NEVER regret the change.

Incidentally - there are relatively few places left in USA which use the High leg Delta idea. It's a seriously bad idea. And afaik, those places in the USA are the only places in the world which are that primitive.

Cheers
Roger