380 volt machine on 480

jraksdhs · Dec 22, 2022

I just got a European spec HLVH that is 380v 50hz. Ive done some digging and it seems it run on just fine on 480 60hz. Anyone have some insight on this? I know the motor will run fine, and there is a transformer in the machine for some of the other electronics. My biggest question is if I just give it 480 will there be in any issues with the other switches and such in the cabinet. I can get a transformer from 230 to 380 but its costly. a 230 to 480 on is a third the price. Any help would be appreciated. Thanks

Peter from Holland · Dec 22, 2022

That should be 440Volts I assume

Peter

pan60 · Dec 22, 2022

if you bumped 50hz to 60 you would be at 456v i beleave? please correct me if i am wrong but that i beleave that would be about correct. and you voltage could vary a fair amout. if it was me i would not be to afaraid to try it? if someone else does not chime in i have a friend who is a guru at this stuff and i will ask him.

pan60 · Dec 22, 2022

i just ask Dan he said.

it will be ok, but run fast at reduced torque.
the inductance of the 50hz winding would oppose the higher frequency, somewhat reducing magnetic field/torque.

so maybe a trabsformer would be in order?

others should know far more then i do.

Garwood · Dec 22, 2022

I have some Chinese hydraulic presses that were 380V. I rewired the motors to the low voltage which was 220 and hooked them up to 240 3 phase. They run noticeably faster than they should and are underpowered. Eventually I will replace the motors.

The motors were easy, it was all the control wiring and heaters that was time consuming to reverse engineer and update for 240. Replace all the heaters. Some of the contactors were undersize at 240V.

On a lathe I would change out the motor. I think the 50 to 60HZ difference will be pretty obnoxious.

Peter from Holland · Dec 22, 2022

Garwood said:
I think the 50 to 60HZ difference will be pretty obnoxious.

Swapping out the motor would not change a thing in speed
You could change the pully on the motor

Peter

Garwood · Dec 22, 2022

Peter from Holland said:
Swapping out the motor would not change a thing in speed
You could change the pully on the motor

Peter

I don't follow you.

On 60HZ the motor spins 20% faster and is less powerful. Replacing the motor with one of adequate HP for the RPM it will operate at on 60HZ should make a positive impact no?

SeymourDumore · Dec 22, 2022

jraksdhs said:
I can get a transformer from 230 to 380 but its costly.

Not to be a jerk, but I do have a 75KVA 240 to 380 V delta/delta transformer for sale ( It is also listed in the for sale section ) https://www.practicalmachinist.com/forum/threads/fs-75-kva-220-380-wye-240-delta-transformer.407862/
I'm only asking $300 for it, but need to figure out how to get it from CT to DE.
It is 405 lbs, so pretty heavy.

SeymourDumore · Dec 22, 2022

Garwood said:
I don't follow you.

On 60HZ the motor spins 20% faster and is less powerful. Replacing the motor with one of adequate HP for the RPM it will operate at on 60HZ should make a positive impact no?

What he is saying is that no matter what, the motor's speed won't change as you're still running it on 60 Hz.
IOW the replacement motor will still run with 3600 rpm, just the same as the original 50Hz one.

Joe Gwinn · Dec 22, 2022

jraksdhs said:
I just got a European spec HLVH that is 380v 50hz. Ive done some digging and it seems it run on just fine on 480 60hz. Anyone have some insight on this? I know the motor will run fine, and there is a transformer in the machine for some of the other electronics. My biggest question is if I just give it 480 will there be in any issues with the other switches and such in the cabinet. I can get a transformer from 230 to 380 but its costly. a 230 to 480 on is a third the price. Any help would be appreciated. Thanks

Get a VFD, and adjust to suit.

jraksdhs · Dec 22, 2022

Joe Gwinn said:
Get a VFD, and adjust to suit.

A vfd wont work unless i rewire the whole machine.

pan60 · Dec 22, 2022

if you changed the puuling by 20% to slow the machine down wouldnt you also pick up the lost power?

Garwood · Dec 22, 2022

SeymourDumore said:
What he is saying is that no matter what, the motor's speed won't change as you're still running it on 60 Hz.
IOW the replacement motor will still run with 3600 rpm, just the same as the original 50Hz one.

I understand that. I spose my perspective is from a using a machine where a motor is driving a hydraulic pump. It's problematic because the 50HZ motor does not have the balls to pump 20% more fluid at the same pressure.

It probably matters less in a manual lathe.

William Payne · Dec 22, 2022

What does the manual say about supply voltage deviation tolerances? 100 volts is a lot. Also it may have somewhere you can change the supply voltage tap. 380/400/415/440 are ones that you may find.

Garwood · Dec 22, 2022

William Payne said:
What does the manual say about supply voltage deviation tolerances? 100 volts is a lot.

No it's not. It's the exact same as taking something made for 110 and plugging it in to 138.

William Payne · Dec 22, 2022

Garwood said:
No it's not. It's the exact same as taking something made for 110 and plugging it in to 138.

What I mean was take one of my machines for example. My supply voltage is 400 volts. But when I got the machine it was tapped 440 so I had to tap it down to 400 because 440 was outside the voltage deviation tolerance that the manufacturer specified.

pan60 · Dec 22, 2022

400 to 440 to me seems a no issue
10% i see that on line voltage?

William Payne · Dec 22, 2022

pan60 said:
400 to 440 to me seems a no issue
10% i see that on line voltage?

Where I live the mandated electricity regulations require supply voltage to be maintained +- 5%. It will depend on what the percentage requirements are for the original posters machine.

technocrat · Dec 22, 2022

For the electrics / electronics, the auxiliary voltage will be the same ratio higher, so your 48V might be 60V. For relays etc they may run hot and possibly burn out coils over time. Depending on the arrangement, it may be wise to replace the small auxiliary supply transformer or change the primary tap to lower the output voltage.

For electronics via a regulated power supply there should be no problem provided the input is in spec. This will depend on if it is powered by the mains or the auxiliaries. It may run a little hotter, so if you see thermal shutdowns you will know why.

markz528 · Dec 22, 2022

Garwood said:
I don't follow you.

On 60HZ the motor spins 20% faster and is less powerful.

Not quite. Can't violate physics which says hp = torque x speed / 5252. Torque is constant to base speed. At 50 hz and 380 volts you have a 7.60 volts/hz ratio and at 60 hertz and 460 volts you have a 7.67 volts/hz ratio so we can say its basically the same. That means that you move your base speed up 20% and have the same torque all the way to base speed because your volts/hz is the same. So torque is the same but speed is 20% higher so the horsepower is 20% higher running at 460 volts and 60 hz versus 380 volts and 50 hz.

So what are the risks? Can the insulation handle the higher voltage? Probably not an issue.

Bigger problem could be if you magnetically saturate the iron. The way you would know if that is happening is if the amps get too high. Amps should be the same at 460 as 380.

Personally, if you can handle the higher speed and horsepower, I would go ahead and try it. The risk is very low.

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