Oh, sorry I misunderstood. I am not doing a very good job in this thread so far.

I thought you meant to put the motor in wye configuration across 230V which would put (1/sqrt(3))*230V=133V across the windings.

But of course you didn't mean that. That is stupid. You don't even have 230V, that's the whole problem isn't it?

You meant put the 230V delta motor into wye so that you can connect it to 400V without any transformer, right? If so, then yes, I think that should work. (1/sqrt(3))*400V=230V so each windings should see the correct voltage it is rated for.

There is no wye/delta start circuit, correct?

Yup.

 

If the motors all run the same speed then one drive might power them all. Then the cost would be less, probably.

I believe so
All run at full speed
But the sled reverses through contactors.
So the grinder moves back and forth

 

Now I realize that we do not have a verification that the TS even has a 3-phase power supply, but only that it is 400 volts. The 3-phase came in post #5 . I am guessing that the supply is three phase, but I am not certain that it has been verified.
There are a number of devices referenced as "cycle-converters" or "cyclo-converters" that do supply three phase from single phase sources. Some of them use rotary converters in some scheme.
But it seems like this is a new machine and that the order became confused and the incorrect product was delivered. So an external transformer package is what is reasonable. So three auto-transformers to step down the 400 volt power seem to be the best option for availability.
It will require an examination of the circuit to determine if a neutral connection is needed for operation, or not. Some systems use the phase-to-neutral voltage to power the control circuits, thus not needing a "controls" transformer.

 

Our system is 220 to 230V
So yes we have 3 ph . 400V nominal
Auto transformer seems expensive than a single transformer though
Regarding VS drives.
I do not think it can handle sudden loads as the 60W motor will reverse.
So stepdown transformer is the viable option.
Or check the motor for a wye connection

Rewiring the control with a neutral is no biggie

 

Our system is 220 to 230V
So yes we have 3 ph . 400V nominal
Auto transformer seems expensive than a single transformer though
Regarding VS drives.
I do not think it can handle sudden loads as the 60W motor will reverse.
So stepdown transformer is the viable option.
Or check the motor for a wye connection
Rewiring the control with a neutral is no biggie

What VS (variable speed?) drives are you referring to?
If this is a standard VFD, when initiating reverse, they will decelerate and automatically accelerate in the opposite direction at the programmed rate, i.e. NO instant reverse.

 

OR.. if they run at full speed, you could use a 3ph Solid state soft-start unit, after the reverser.

 

I had not thought about a soft start package. Good Call, Max.
Based on the functions described in post #22, this seems like a surface grinder of some sort. The back and forth does have a pause after stopping to reverse, I think that surface grinding requires a constant speed while the wheel is in contact, at least that seems reasonable, so the operation will need the start and accel outside the work zone. That might be a problem. Softstart systems should cost less than VS drives.
An auto-transformer uses less copper than any other kind and so it shouldcost less. And I think that I have seen three phase autotransformers. Check the Hevi-Duty catalog.

 

Never saw or heard of a surface grinder using electric motors for the lateral back and forthe speed. Any powered talbe grinder I've ever seen or heard of uses hydraulics for table movement. The hydraulics take the rack and pinion "bumping" motion out of the surface finish.

 

Never saw or heard of a surface grinder using electric motors for the lateral back and forthe speed. Any powered talbe grinder I've ever seen or heard of uses hydraulics for table movement. The hydraulics take the rack and pinion "bumping" motion out of the surface finish.

Did you know a country called "China" ?

 

Here is my idea to run the machine
Each single Txfmr will be rated for around for 700VA.
Machine total is 1.2kW, so 1.5kVA
Considering the running hours, I am adding 20% more. The total Txfmr will be 1.8kVA ish.


This way I can do away with just 3 nos 700VA, 230VAC to 230VAC Isolation Transformer.
What do you say?

 

That will work quite well.

 

I was able to convert the two motor to wye connection and it works at 400V.
The smaller 40W one is wound to 220 wye, so it was a no go.

 

I was able to convert the two motor to wye connection and it works at 400V.
The smaller 40W one is wound to 220 wye, so it was a no go.

For running the 40 watt motor you can use two transformers, and an open delta configuration, if it can be rewired to delta.. OR a small rotary converter. What is the function of that motor? Initially contactors and other parts of the control system were mentioned. How are they being powered??
Does the machine include a controls transformer?
Worst case you might get a VS driver for that motor. Automation Direct has VS drives at much better pricing, at least they did a few years back. And a small VS drive would have a lower shipping price than a transformer.

 

The small on is just the water pump. Trying to find a single phase one for tht. Even a good fish tank pump will do I believe

 

I was thinking water pump and those are more common items, so locating a replacement with the needed voltage should be simpler.