Mini Mill 2 single phase wiring - help, please!

I've just bought a 2008 Mini Mill 2 which has previously been running on 3 phase. My understanding is that this machine is capable of running on a 240v single phase connection which I am attempting to do, however I am somewhat confused by the connection details.

The connection details in the operator's manual state:

"For single phase operation, only terminals L1 and L3 on the circuit breaker are used ... L2 should be left open", which is fine, but I am wondering if the connection is polarity specific, i.e does live go to L1 and neutral go to L2, vice versa, or are the connections are non-specific?



The next section goes onto describe the connections on the T5 transformer, which I'm fine with.



Section 3 goes onto mention the main transformer located to the bottom right of the cabinet and makes mentions of two input connections located on "TB2" - Terminal board 2, and instructs where to connect "Wire 74", depending on the voltage. The problem I seem to have is that no Terminal board 2 seems to be present in my machine.

The only connections I have from the transfomer are:

A twisted black and red pair which leads to the power supply board, located next to the main breaker.

A connector (two blue and one purple wire) which is connected to the 320v power supply and labelled 230v to 300v.


A connector (two brown wires and one grey) which is not connected to anything but labelled 366v to 395v

A connector (yellow and two red wires) which joins on to another connector and then off to the main breaker.



Additionally, on the transformer is has a sticker which states "Check the volatge at the main cicruit breaker, then select the proper connector on this transformer"

Finally, the instructions mention to check the DC bus voltage between pins 6 & 7. I cannot seem to find the DC bus, I assume that this is different on my machine too?


If anyone could shed some light on it all, I'd be very grateful.

Many thanks.

I think you need to involve an electrician. On 240 volt single phase services both conductors are 120V to the neutral conductor, but 240V between them. Based on the description in your first paragraph, the 240V conductors from the panel can be connected either way, but the neutral conductor (normally white) is not connected at all. Be certain the green safety grounding conductor is properly connected to the machine.

I can't help you with the rest.

Stainless00 said:

, but I am wondering if the connection is polarity specific, i.e does live go to L1 and neutral go to L2, vice versa, or are the connections are non-specific?

Click to expand...

Stop right here.
An electrician or tech is cheaper than blowing out a board.
Perhaps someone on the net can lead you through it but one mistake and you fail the smoke test.
This stuff is also not house wiring so best a machine or industrial electrician, not a guy that wires the panel and plugs for homes (different worlds and skill sets).

I am all for do it yourself but I did blow up a few things learning in my "exuberant youth".
When guessing you disconnect the output at each section/device. Hook up and measure what is going out, step onto the next.
Do you have a wiring print and know how to read it? The missing board should not be a big deal.
Baby steps.
Doubtful you will hurt it but you might spend a lot of time and when running it might not be quite right.
Bob

wheels17 said:

I think you need to involve an electrician. On 240 volt single phase services both conductors are 120V to the neutral conductor, but 240V between them. .

Click to expand...

He is in the UK, ergo he does use L1-N for 240V.

As to the wiring, It won't matter.
The only 3ph consumer in the Minis is the 320V DC power supply for the servos, and I am sure it can figure out how to create it, as long as the inputs are on 1 and 3.
The main transformer on the bottom is a simple single phase tranny for 120V ( coolant pump, llights etc )

Regarding the TB2, my guess is that machine is a European model, where 240V is pretty much everywhere.
Here in the US we can have anywhere from 208 to 250, some folks might still be on old-old transformers with 190V
Hence, US models typically include a multi-tap transformer, and it's inputs are brought out to TB2.
Black - Common ( L2 in the US, N or L1 everywhere else )
White - 208V
Red - 240V

So, in your case there is no white, incoming power is connected to red and black. If you want to be particular and feel good, ohm out the wiring from the black
wire to either L1 or L3, whichever terminal is short, put the Neutral there.

(sidenote: Pretty sad Haas doesn't supply a European version of the installation portion of the manual )

As already mentioned, 230V single phase power will have two hot wires, so polarity is unimportant. Unless there is a separate connection for a neutral (I doubt it, they probably use a transformer for lower voltage needs) there would be no neutral connection. There should always be a ground connection.

Does the transformer list different voltage ranges like 200-215V, 216V-230V, etc? You are supposed to connect the wires to the voltage range that encompasses your actual voltage.

The DC bus is a voltage, not a thing. They are telling you to measure it between pins 6 & 7. I would imagine they should tell you on what board or connector these pins are located.