CNC Transformer - Delta to WYE question and is it big enough?

[barchdesigns]

Hi, I am in the process of moving my shop from a place that has true 3 phase power to a place where I will be running a 3 Phase Rotary converter. I would like to get true WYE power by using a transformer and do it on a budget. I have 2 CNC machines: A Mitsui Seiki VR3A with no main transformer (it was obviously removed years ago), and a Mazak QT10 with a 22.5 KVA transformer. I am only ever going to be running 1 machine at a time and was thinking I could wire both machines up from the Mazak transformer.

I am not an electrician, but know enough to get myself into trouble. I can't quite tell if this Mazak transformer is Delta to WYE. Are most transformers Delta to WYE? I have attached some pictures. Can anyone tell if this is a Delta to WYE transformer?

I also have the option to buy a 45KVA transformer that I am certain is Delta to WYE and would work, but would like to save the money if I can.

Secondly, are these transformers big enough? I haven't found a KVA rating for the Mitsui Seiki VR3A, It has a 10HP spindle motor, and I have measured 45-50Amps as the max Amps when the spindle is spinning up quickly. Most of the time each leg pulls about 10Amps.

Close Up of Transformer
Overall Pic of Transformer

Thanks for your help,
Benjamin Barch
Barch Designs
877-201-9771

[Al_The_Man]

The transformer looks definitely Wye or star secondary, probably delta pri.
I don't see the star point though, unless the ground wire is connected to it?
Is there any reason you want or need the Wye secondary?
The KVA should be just about OK, you always monitor the temperature.
Al.

[barchdesigns]

The reason I would like to go WYE secondary is because the Mitsui Seiki has a lot of things wired from 1 leg for 110V and I don't know if all of the 110V taps all come from a single leg or if they are tapped from any random leg.

For instance, I wouldn't want my cooling fans or coolant pump to be wired to the WILD leg of the RPC. I figure a transformer will guarantee me the 110V from any secondary leg instead of the 250+V of the wild 3 phase converted leg.

Also there used to be a main transformer on the Mitsui Seiki machine at some point. It was obviously removed and the wires are just connected together. That leaves me worried that it had a transformer at one time because of Delta power from a RPC. I figure a transformer will cover all my bases and give me some piece of mind.

FYI the Mazak has a 15HP motor so I was hoping the transformer from it would run the Mutsui Seiki with a 10HP motor. The transformer is actually a 28.8KVA total, but the main 3 phase output is specifically marked 22.5KVA.

Sounds like I am on the right track. Thank you Al. As always I am amazed by your quick and detailed reply.

[Al_The_Man]

The vast majority of commercial machine tools have just three phase in and use a 1ph transformer in the enclosure for the 120vac control. If this is the case, you could just make sure the generated leg does not feed this Txfmr.
There are older ones that use a 3ph txfmr specifically for a DC spindle that uses a 1/2 wave SCR bridge with a star neutral point for the centre of the 1/2 wave bridge.
But if you have AC spindles this should not apply.
Al.

[barchdesigns]

That makes a lot of sense. After closer inspection in the cabinets it appears that this may be the case here too. I see R and S feed a transformer that outputs 100V. T seems to be the leg that isn't hooked to anything except things that take all 3 phases in. So in theory I should just have to make sure T was the wild leg connection.

I probably will still use the transformer just to err on the safe side considering I already have this transformer and it only can help by hooking it up. It would really hurt the budget if we broke our CNC machine and had to pay for repairs.

Thank You

[mike_Kilroy]

u cud drw out the pri connections picture for both 230 and 460v conextions to see if delta, but that is immaterial to ur desire; u just want Y secondary and it says right on nameplate Y. so u r good to go there.

BUT know that u will NOT get 110v from sec line t neutral! that is for ur house which is single phase center tapped! 230v sec to nuetral will give u 230/1.73 or 132 or higher if 240v output.... not same. but as Al stated, those machines should have a control xfmr for their 100v use anyway.... and yes plenty big for the smaller machine too.