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The smallest physical size 230/400 volt 3 phase transformer... 7.5 to 10 kva..

Milacron

Milacron

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Dec 15, 2000
Location
SC, USA
Needed to run European lathe 5hp, 400 volts... and would like to bolt it to the rear base of the machine if possible. Know of any like this in 3 phase ? Or perhaps three single phase units ?
 
I have 3 such transformers; From memory, I guess 18" x 6" x 18".

The 3 coil bars are bridged together in a line. I believe there's some added efficiency in that.
They get a bit hot when loaded, so need ventilation to avoid meltdown.

I bought them 15 years ago or more, as I recall they were around $1,200 each.

Around 100 lbs each I think. Maybe a little more.
 
Euro Voltage 3Φ Transformers

Here's a couple of samples to look at, depending on whether you need an isolation unit or an auto-transformer type.

The isolation units are one size bigger than requested as standard, 15KVA, smaller units can be custom quoted. Auto-transformer type if acceptable for you use is available in a 9KVA size.

3-Phase 240V Delta - 400 Y 231 (Step Up Transformer)

3-Phase Encapsulated Autotransformer 600-480-400-240-208v

TEMCo Euro Standard Transformer TT1031 - 15 kVA

9 KVA 3-Phase Multi Tap Auto Transformer (600,480,400,240,208V)
 
A dry-type transformer will be the largest. Encapsulated type will be smaller, but they may not be available in the sizes you're talking. Autotransformers will be the smallest since they only need to be sized for a portion of the load, but you will need at least two of them. Three if the machine requires balanced voltages to ground for some reason.

As mentioned above, it might be easiest to hang a dry-type transformer with unistrut, threaded rod and drop-in anchors or beam clamps. It is common practice where space is an issue. Adherence to the manufacturer's mounting clearances is crucial to assure adequate convection will occur for cooling. Install a disconnect within sight of it and provide transformer overcurrent protection in accordance with 450.3. Transformer secondary overcurrent protection in accordance with 230. Grounding and bonding in accordance with 250. Size the wires based on 310.
 
I hope you've considered the frequency issue; the 50Hz motors will have a higher RPM when you connect them to US 60Hz supply.
 
Careful using a transformer like that without it's proper enclosure. The windings in dry-type power transformers can get up to 150*C at full load during normal operation. In exchange for a small form factor they require a lot of airflow to stay cool. Any 60*, 75* or 90* rated conductors in the same air space positioned any higher than the lugs on that core will get cooked to a crisp in no time. That's why the wiring always enters dry transformers at the bottom on a proper installation. Often they're even marked on the inside at the highest point field wiring can be installed.
 
Last edited:
jmkasunich said:
This one would work. No enclosure, that could be a problem or an advantage, depending if you could fit it in the machine somewhere.

Used Siemens Transformer | HGR Industrial Surplus
Click to expand...
I guess I should have clarified this is not just a one time use as the transformer would be bolted to new lathes we will be selling. Thus it has to be new while being as physically small and cost effective as possible. Milacron
 
I don't think you need anything. Set the machine up for 400 Volt and connect it directly to 460V. Because the line frequency is 20% higher, so will be the motor reactance (AC resistance), so the motor will not draw an excessive amount of current. The reactance formula is: XL= 2PiFL. The motor speed will also be 20% higher, but a simple pulley change should sort that out. Try it and see, worst case is you'll pop a fuse.....so what.
 
steve-l said:
I don't think you need anything. Set the machine up for 400 Volt and connect it directly to 460V. Because the line frequency is 20% higher, so will be the motor reactance (AC resistance), so the motor will not draw an excessive amount of current. The motor speed will also be 20% higher, but a simple pulley change should sort that out. Try it and see, worst case is you'll pop a fuse.....so what.
Click to expand...

He wants to sell these in the USA, from the way I understand it. And very few shops in the USA, smaller than a big factory, have 460 volts.
To reach the widest base of potential customers, he needs 220/240 volts.
 
Admin5 said:
I guess I should have clarified this is not just a one time use as the transformer would be bolted to new lathes we will be selling. Thus it has to be new while being as physically small and cost effective as possible. Milacron
Click to expand...

Gotcha - that certainly changes things.

Are you talking one or two a year or dozens/hundreds?

You might be surprised at how affordable semi-custom transformers can be. Try contacting some of the big manufacturers like Hammond or Sola-HeviDuty.

This is an interesting voltage ratio. The actual windings could be 1:1, with each winding rated at 230V. Input would be connected in delta, giving 230V line-to-line. Output would be connected wye, giving 230V line-to-neutral which works out to 400 volts line-to-line. That means the manufacturer could take one of their standard 1:1 drive isolation transformers and reconnect it for you. Could be economical even at low quantities.

Only way to find out is give them a call.
 
Admin5 said:
For this one- 3-Phase Encapsulated Autotransformer 600-480-400-240-208v – Maddox Industrial Transformer .... I would need 2 ? Why ?
Click to expand...

Not sure what Just s Sparky had in mind when he said two. Maybe thinking of using two single-phase units in open-delta. The listed 3-phase autotransformer should work fine by itself. Overcurrent protection and other code issues for autotransformers can be more complex to interpret compared to regular transformers but when the dust settles should not be any more expensive (and could be cheaper)
 
If you're manufacturing these machines, why not order the same frame size motors wound for dual-voltage 240/480V service? The cost of special-ordering motors for North American service ready to go from a European manufacturer would probably be considerably less than the material and labor cost of adding transformers, installing disconnects and overcurrent protection, grounding and bonding as necessary, etc. You're talking about a lot of extra time in production. Using the right motors would also be the smallest, most efficient option as well.

If you're not constrained by an IEC frame size, you could even order NEMA motors from the US and have a batch of them freighted over.

EDIT: As for above, yes - in my experience most autotransformers I've run into have been individual single phase units. Two of them for an open delta. But if you can find a three phase unit then that would work just as well.

Double EDIT: Oh, I get it. You're importing European machines and selling them in the US market. A motor swap might still be the simplest and cheapest option if there are no control circuits involved. That way you can recuperate your material costs by reselling the EU motor. By adding a transformer you're only putting money into it and not getting any back out, so your costs will go up as well as the price tag the customer will see. On paper it would be less competitive... unless there's more to it than simple standardized-frame motors and control transformers.
 
Just a Sparky said:
If you're manufacturing these machines, why not order the same frame size motors wound for dual-voltage 240/480V service? The cost of special-ordering motors for North American service ready to go from a European manufacturer would probably be considerably less than the material and labor cost of adding transformers, installing disconnects and overcurrent protection, grounding and bonding as necessary, etc. You're talking about a lot of extra time in production. Using the right motors would also be the smallest, most efficient option as well.

If you're not constrained by an IEC frame size, you could even order NEMA motors from the US and have a batch of them freighted over.
Click to expand...

That just reminded me of something else. Americans use 9-lead motors that can be configured with two windings in series for 460V or two in parallel for 230V.
Europeans often use 6-lead motors that can be wired in wye for 400V or delta for 230V. Check your motor nameplates - you might be able to convert them to 230V without anything special at all. If they are hard-wired in wye with only three external wires the supplier might be able to swap for the 6-wire version, or offer you a version that is hard-wired delta. Note that converting the motors to 230V will increase the full-load current by a factor of 1.73, meaning you might have to upsize wiring, contactors, etc, and will certainly have to adjust overload relays.
 
Or better yet, order the lathes motorless and install your own! Tell them to include a NEMA size 1 or equivalent starter and appropriately sized wiring. Stick the right heaters in it, slap the motor in and away you go.

Add a fusible disconnect if needed for short circuit/ground fault protection or let the customer install their own where they want it.

That would save a ton of time and money.
 
jmkasunich said:
Europeans often use 6-lead motors that can be wired in wye for 400V or delta for 230V. Check your motor nameplates - you might be able to convert them to 230V without anything special at all.
Click to expand...


That used to be the case, but for a while now most EU machinery is delivered with 380 / 660 motors, as (I was told) factories are running 660V.
I needed a 220 3-phase machine and I had to special order it.

Regarding the original inquiry; If these are new machines, I'd ask the factory to advise on what motor options they can offer.
If they're used machines, I'd look at what motor voltage options are on the motors that come with it, and go from there.
 
mark in Portugal said:
That used to be the case, but for a while now most EU machinery is delivered with 380 / 660 motors, as (I was told) factories are running 660V.
I needed a 220 3-phase machine and I had to special order it.

Regarding the original inquiry; If these are new machines, I'd ask the factory to advise on what motor options they can offer.
If they're used machines, I'd look at what motor voltage options are on the motors that come with it, and go from there.
Click to expand...

Motors up to 4kW are typically 230/400. Motors 5.5kW are typically 400/690. Using a 400/690 motor allows it to be started star/delta on 400V.
 
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