Mini Mill Phase detect light

[slatern44]

I just had my shop wired for 3-phase power about 2 weeks ago because of buying a new VF-2. So I had my two mini mills switched over to 3-phase power now since I have the option. But one of them has the phase detect light on and the other does not even have a light on it to detect correct phasing. So I called Haas and they said the light needs to be off and to call my electrician that did the wiring and have him correct the phase. In the mean time selway came out and did my instal on the new VF-2 and I showed them the light on and they said the same thing. Fix it or it could burn up your coolant pump or computer. The electrician was here this week and tried everything to get the light off and failed (even talk with Haas for about 1/2 hour trying different things). We finaly got smart and opened up my other Mini Mill and checked it out and it does not even have a light in that spot. The words are there but the bulb is not put in. Then selway service manager gave me a call and said dont worry about it, that's why your newer mini does not have that bulb. So my question is if you have a mini mill on 3-phase power would you open up your back panel and see if you have a phase detect bulb and if yes, is it on.
Thanks.

[Al_The_Man]

I can't see it burning out a computer, it is probabally on 1 phase.
Usually phase detectors just indicate phase rotation so that any three phase motors will rotate the right way when power is applied, but you would know right away when you start one of the 3ph motors?
Some are just indicators, some actually lock out a main contactor to prevent any power up where safety is an issue, as used in elevators etc.
I am not sure why they would bother with something like a CNC m/c.
Al.

[slatern44]

I'm not a electrician but it I think it because they dont want the wild leg of the 3-phase to burn up or over turn the coolant pump or computer. I think they said the computer power if off leg a, wild leg is b or center and coolant power comes off leg c. But I could be wrong on this.

[Al_The_Man]

I don't quite see how a phase rotation detector can guarantee the artificial leg of an RPC can only be be applied to one particular phase?
You could swap the 2 main 1phase conductors to reverse it the phase rotation?
It is true however you do not want the artificial phase to feed the computer.
Al.

[wms]

OK this should muddy the waters even more..

Been this way since day one..2000 Model Mini Mill 3ph 230 volt..

[Donkey Hotey]

I just recently learned that some incoming industrial power may also have a 'wild leg' (similar to a Rotary Phase Converter). If you aren't familiar, basically: it has to do with the wiring of the transformers upstream of your location. Here's how you check for it:

Using a VOM, measure from the ground wire to each of the three incoming power lines. If all three are the same (110-120V) then you have Wye wired power and you don't have a 'wild leg'. If two measure 110-120 and the other measures over 200V, you have Delta wired power. The higher voltage leg is the one people are calling 'wild'.

If you have a 'wild leg' of voltage, it should be connected to the center connection of the incoming power (B). Haas told me it makes no difference and that the machine can handle delta or wye wiring without a problem, on any phases.

I won't bore you with why but the machine does indeed use legs A & C to generate other voltages in the machine. In the purest sense, it is better to wire the 'wild leg' to the center tap but Haas still insisted that it made no difference. I sleep better knowing that the computer has a proper ground.

So:
If you have a wild leg (Delta power):
Wire the wild leg to the center phase.
If the FAIL light is on, swap the two outer wires to correct. The PASS light should now come on.

If you have no wild leg (Wye power):
Wire the three incoming to any terminal
If the FAIL light is on, swap any pair and the PASS light should come on.

Two more things you should check:
There are taps on the main transformer in the bottom of the cabinet. They are supposed to be connected to the proper voltage for the incoming power. Make sure that the voltage measured across any pair of incoming lines matches the tap position on the transformer.

The other is the low voltage power supply jumper in the upper right corner of the cabinet (near the incoming power, the main contactor and the circuit breaker). It has a white nylon jumper that plugs into one of two locations (IIRC). It's like the transformer: set it to the proper incoming voltage level.

Disclaimer:
There are some very seriously high voltages in the back of that cabinet. I had the ground ring of my oscilloscope probe bump against the DC 325V screw when looking for voltage problems and the last 0.5" of the probe exploded! The 'pop' was like a gunshot and my ears rang for 30 minutes. There are voltages in there that will kill you. The DC power supply / vector drive stores that kind of power, even after the incoming line is disconnected (watch for the 'high voltage light' to fade out before it's safe). This is no joke. If you aren't confident working around high voltage electricity, don't go digging around in there.

Even if you are confident, try to use the 'one hand' rule (avoid having two hands on the machine). High voltage on one hand will bite or burn you but two hands and the voltage passes through your chest. Not good.

WMS: that photo is priceless. I guess all the checking in the world can't fix everything.

[Al_The_Man]

I can't believe that a responsible company would not set up a local isolated 120vac supply for control purposes complete with grounded neutral.
This would eliminate all the apprehension about different 3 phase configurations causing problems.
Al.

[Donkey Hotey]

Originally Posted by Al_The_Man I can't believe that a responsible company would not set up a local isolated 120vac supply

'Isolated' is the key word there. In truth, they really do isolate the power in the machine. In fact, they are so careful about isolating things that they are able to make that statement that 'it doesn't matter'.

In fact, I don't think most owners (or even techs) would know it unless they started probing around with an oscilloscope. I found it when I discovered that my 325V DC power was swinging up and down on a 115V wave. Measured leg-to-leg, it was 325V but referenced to ground, it was all over the place. IE: there is no true 'neutral' on the high voltage DC portion of the machine.

Because of all of the electronic noise in a CNC machine, they have isolated everything from everything else. It's really brilliant how some of it is done.

But at the end of the day, I like to eliminate 'potential' electrical problems and noise before they start. I prefer to be careful about connecting the A & C legs to the good legs and letting B go wild which is the way the machine is wired.

[slatern44]

WMS,
That looks the same as my January 2006 mini, but my October 2006 mini the bulb was never put in. I guess they finally got tired of people asking "is this light suppose to be on?" The machine runs fine this way just trying to check to see what you guys thought. Haas still says the light should be off, selway says dont worry about it. Either way I still get to pay the electrician bill for checking it out.
Thanks.

[Al_The_Man]

Originally Posted by Donkey Hotey CNC machine, they have isolated everything from everything else. It's really brilliant how some of it is done. But at the end of the day, I like to eliminate 'potential' electrical problems and noise before they start. I prefer to be careful about connecting the A & C legs to the good legs and letting B go wild which is the way the machine is wired.

They appear to have gone against current convention it is not all that often you see the 'Isolate everything philosophy in a CNC machine.
In the systems I do, I prefer the opposite, conventional bonding of all the power supplies to a common ground buss that is connected to the system ground.
A Delta supply with a neutral is relatively rare, but most machines are usually equipped with internal transformers that provide isolation anyway.
Al.

[Donkey Hotey]

As Al already pointed out, I don't know what the phase detect light is for anyway. Almost everything in my machines is run from some form of rectified DC.

The only things that would care about phase are motors running straight from the incoming AC power: high HP coolant pumps, hydraulic pumps or other accessories like that.

[Geof]

Like the song goes; " ...don't worry, be happy... ".

If you have a lathe with a three phase drive hydraulic pump then you should make sure the phasing is correct before pushing RESET the first time the machine is powered up.

When there are no three phase motors running direct from the incoming three phase supply the phasing is irrelevant.