Newbie needs help with KM3P

[freak_brain]

Hello Good friends!!!

I recently purchased a Hurco KM3P machine. Before putting power to it I have a few items I need to take care of. This is where I need your help!!!

First.... power

This machine was ran on 480 3 phase. I am putting this in my shop at my house. Guess what.... no 480. I have a phase converter that I made myself. Simply put it is a 15hp 3 phase motor that I use to make the third leg. So, I have 230V 3 phase.

Are there any known problem using this type of phase converter on a cnc?

Changing the wiring on the motors are pretty straight forward but I'm not so confident when it comes to the transformers. I added a picture to this post as to what I think I have to do to them. There is only one transformer in the picture but the wiring on the other is exactly the same. I wrote on the picture what I thought I should do to make them work with 230V.

Does it look correct to you electrical gurus?

After posting this I noticed you can't really read what I put on the picture so I will try to explain it if I can.

On the front of the transformer there is a terminal block on a din rail. there are 4 wires coming into the bottom labeled, from left to right, H1 H3 H2 H4. On the top there are two wires. The wiring information on the front of the transformer states...

230V

L1. H1-H3
L2. H2-H4

480V

L1. H1
L2. H4

So I read that as this. H3 and H2 are hooked to nothing (480V wiring). If I jumper H3 to H1 and H2 to H4 that should make it work with 230V. Does that sound correct??

Also. How do I properly ground the machine so that I don't have any ground loops problems?

Thanks for any help you may have to offer!!
Allen James

[skullworks]

Note that the only item that uses 3ph power is the spindle motor. (on some models the coolant pump might be 3ph)

Personally I would make some space in the left side cabnet by moving or eliminating contactor units and mount a VFD there - The VFD can then handle direction and even tweak your top and bottom speeds. Also using VFD breaking will extend the life of your mechanical spindle break.

This method is "cleaner" and will use less power than a constant on motor type phase converter.

[freak_brain]

skullworks,

thanks for your reply!!! Can you be so kind to tell me what a vfd is?

Thanks
Allen

[freak_brain]

skullworks,

I found out what it is.... variable-frequency drive, but how does it help me? Also, if I use one of these can I just power the transformers and the motors with single phase?

Thanks
Allen

[skullworks]

A VFD is in effect a variable phase converter.

Most units up to 3hp can take 1ph in and put out 3ph and by adjusting the freq from the normal 60Hz it can also control motor speeds within reason. "Cheap" VFD's might have a range of say 40Hz to 90Hz while a higher end model might be functional from 20Hz to 400Hz. Now some motors can not handle the extra heat from running beyond certain limits so its best not to try to push a nornmal fixed speed motor to far outside its normal operating range.

This would act as to power supply and direction control for your spindle motor. So the forward and reversing contactors are not needed.

Most likely everything else in the cabnet can run of normal 110VAC. You might wire it up with 220 in and put the Servo power on one leg and the control on another. Consult a real Electrician about your options.

[freak_brain]

Skullworks

If I understand this correctly the vfd would replace the contacts and would also change the "power in" requirements to single phase? Also, with the motor(s) I have I probably don't want to work to far from 60hz because of the heat issues? Not that I would do this myself I am just trying to get some information so I know what I am talking about when I look for a "qualified" electrician.


Thanks again for the help!!!
Allen James

[skullworks]

I know the KM3P had some type of motor to adjust the Vari-drive Speed - I don't know what it was. I thought it might be a stepper.

I worked on a KM3 (only difference was it did not have the "P"rogramable speed control.) for 12 years.

In fact I know it gave up the ghost a few years back and I have been trying to talk them into selling it to me. I could bring it back to life with EMC2.

[freak_brain]

I know the KM3P had some type of motor to adjust the Vari-drive Speed - I don't know what it was. I thought it might be a stepper.

I worked on a KM3 (only difference was it did not have the "P"rogramable speed control.) for 12 years.

In fact I know it gave up the ghost a few years back and I have been trying to talk them into selling it to me. I could bring it back to life with EMC2.

Here is what I do know.... which isn't much!!

The motor for adjusting the spindle rmp has a set of contacts that has three phase running to it. They are labeled as 4MI and 4MD. The book states they are spindle rmp increase and decrease contacts. That would lead one to believe it is a 3ph motor. I was wondering how they got the rmp correctly with that, maybe a tach?

The variable speed drive is the only difference between the km3 and the km3p?

Allen

[skullworks]

The variable speed drive is the only difference between the km3 and the km3p?

Allen

Yep. In place of that motor the KM3 just has the same little crank like any other BP clone.