What's new
What's new

380 volt machine on 480

Just reread the original question - will other components be ok?

I would think you would be ok. Because you are not just changing the voltage - you are also increasing the frequency so the volts/hz stays the same (see my motor comments). When the frequency goes up the impedance goes up so the current should be the same because volts/hz is the same. There might be some additional heating, but I personally don't think it would be a problem.

But I have not personally done it so can't say 100%.
 
One issue that I think would be a pain is how it would effect the rpm for machining. As all the gearing will be based on what it should be factory. I am not hugely familiar with that aspect of a hardinge.
 
Last edited:
Some loads are non linear, 380 on a 50hz motor will work fine with 480v at 60hz on most machines.

If the motor can't keep up then it was overloaded to begin with in my opinion.

This doesn't hold past about 50% more volts and hz due to the impedance limitations, but if you run into that problem... Again the motor was overloaded to begin with in my opinion.

Also 380 at 50hz is 456v at 60hz, so if you really are feeding it 480 you will have enough extra volts to get the same torque out of it.
 
Last edited:
The key to operating any AC powered piece of equipment is understanding the magnetics associated with supply voltage and supply frequency. This relationship is what a typical VFD exploits in the constant torque region of operation below motor base speed (frequency) and this operational mode in the drive is called V/Hz mode.

380V/50Hz yields a flux density of 7.6 V/Hz . . .

60Hz x 7.6V/Hz = 456V as previously mentioned.

In order to maintain designed flux density you can operate the machine at 456V with a 20 percent increase in speed and in respectful disagreement with all comments above, NO LOSS in torque (I.e. the motor delivers a 20% increase in power) . . .

If you look at the ratings of the vast majority of 3-phase motors intended for operation in North America they are 208, 230/460, or 575 Volt rated. A 460V motor has a flux density of 7.666…V/Hz which is less than 1% difference in flux density from a 380V 50Hz motor . . . or for all practical purposes interchangeable with a rerating of a 20% increase in speed AND power with no difference to duty cycle rating.

Also, here 460V 60Hz motors run long lives at 480V without issue as would your 380V 50Hz rated inductive loads on 480V, 60Hz.

Any resistive loads are another story, pilot lights would be of particular concern.
 
Last edited:
The key to operating any AC powered piece of equipment is understanding the magnetics associated with supply voltage and supply frequency. This relationship is what a typical VFD exploits in the constant torque region of operation below motor base speed (frequency) and this operational mode in the drive is called V/Hz mode.

380V/50Hz yields a flux density of 7.6 V/Hz . . .

60Hz x 7.6V/Hz = 456V as previously mentioned.

In order to maintain designed flux density you can operate the machine at 456V with a 20 percent increase in speed and in respectful disagreement with all comments above, NO LOSS in torque (I.e. the motor delivers a 20% increase in power) . . .

If you look at the ratings of the vast majority of 3-phase motors intended for operation in North America they are 208, 230/460, or 575 Volt rated. A 460V motor has a flux density of 7.666…V/Hz which is less than 1% difference in flux density from a 380V 50Hz motor . . . or for all practical purposes interchangeable with a rerating of a 20% increase in speed AND power with no difference to duty cycle rating.

Also, here 460V 60Hz motors run long lives at 480V without issue as would your 380V 50Hz rated inductive loads on 480V, 60Hz.

Any resistive loads are another story, pilot lights would be of particular concern.
So having said all this, would you think the machine would need anything else other than a step up transformer from 230 to 480? Any other wiring changes needed inside the main cabinet? I can post pictures of some of the electrical components if needed.
 
If there is a rectifier in the auxilary equipment you have to make sure their input so thereby their output stays the same I assume
If you use DC contactors or other DC device the frequentie is of no influenze
Peter
 
So having said all this, would you think the machine would need anything else other than a step up transformer from 230 to 480? Any other wiring changes needed inside the main cabinet? I can post pictures of some of the electrical components if needed.
You say you have 230V . . . is that 230V single phase or 3-phase? If it is 230V single phase and are running a rotophase, you can purchase a 3-phase transformer and take advantage of any taps to balance phase voltage, again . . . 90% of them are rated 2:1 so if you feed it with 230V you will get 460V out of it which should be fine. . . . if you have 230V 3-phase, same drill without the concern for taps for voltage balance.
 
Thank you for the great explanation
One more question
Does this also count for coils in contactors ????

Peter
Generally yes - although snubbers / surge suppressors on coils often have a voltage limit that you want to stay well under.

As an extreme example I have run a 480V VFD -> sine wave filter -> 480:4160 transformer -> 1.5km undersea cable -> 4160:480 transformer -> sub-sea tidal generator operating from 4Hz to 75Hz no problems . . . just need to maintain the proper V/Hz ratio and all is fine.
 
You say you have 230V . . . is that 230V single phase or 3-phase? If it is 230V single phase and are running a rotophase, you can purchase a 3-phase transformer and take advantage of any taps to balance phase voltage, again . . . 90% of them are rated 2:1 so if you feed it with 230V you will get 460V out of it which should be fine. . . . if you have 230V 3-phase, same drill without the concern for taps for voltage balance.
I have 230 3 phase via a rotary. Currently looking at this unit from Larson Electric. These are the two transformers in the machine. The legrand one is has wires hooked up to the 0 and 400 on the top and 0 and 230 on the bottom. The other one has many taps. Im assuming that 415 tap is for the main motor since its name plate says 415. Just so Im clear, you're saying supplying the whole machine with a 460 service(via the step up transformer) directly to the main disconnect at L1 L2 L3 will be perfectly fine and I wont have to do anything else inside the cabinet? Also, any issue with in that 3rd pic with the breakers? I see a voltage of 415. Is that going to pose an issue if Im supplying it 460?
 

Attachments

  • IMG_4685.JPG
    IMG_4685.JPG
    545.7 KB · Views: 5
  • IMG_4686.JPG
    IMG_4686.JPG
    593.1 KB · Views: 5
  • IMG_4687.JPG
    IMG_4687.JPG
    585.9 KB · Views: 5
without a schematic - all of your questions will be answered with guesses . . . best for you to work your way through each circuit, document it, and ask questions pertaining to each with proper details.
 
The Legrand transformer is for the outlet for the DRO
The machine has no neutral So I put this transformer inside
There is a schematic in the door but thats so vage you cannot see anything on it
Look for a clearer one on the internet Probably the shematic nr is still readable
The multi tap transformer is for the auxillary only and the powerfeed motor I guess Not for the main motor
The drive for the DC motor for the feeds must get the proper voltage as it gets rectified (within reasson )

The machine is 380 volts It says so on the machineplate on the door
Does the plate on the main motor says 415???? That would be wierd

Peter
 
The Legrand transformer is for the outlet for the DRO
The machine has no neutral So I put this transformer inside
There is a schematic in the door but thats so vage you cannot see anything on it
Look for a clearer one on the internet Probably the shematic nr is still readable
The multi tap transformer is for the auxillary only and the powerfeed motor I guess Not for the main motor
The drive for the DC motor for the feeds must get the proper voltage as it gets rectified (within reasson )

The machine is 380 volts It says so on the machineplate on the door
Does the plate on the main motor says 415???? That would be wierd

Peter
Yes, 415 50 hz. So that 415v tap on that transformer that has a wire in it isnt for the main motor?
 
We are looking into detail y
Yes, 415 50 hz. So that 415v tap on that transformer that has a wire in it isnt for the main motor?
No The motor is 3 ph This is not a 3ph transformer
But wierd that one plate says 380 the other 415
This machine is produced in the UK where 3ph 415 volts is normal Thats probably why

Peter
 
Hello

I live in Europe. (Sorry for my bad english...)

Now, in my shop voltage is already between 400 and 415 volts. But my oldest machines were designed fo 380 Volts. There is no problem for the moment.(25 years use.)

Regarding the frequency, if you use 60 He for supplyind a 50 Hz motor speed will be increased by 60 %.

I have several american machines designed for 60 Hz. In France they ate running 20% slower than in america.

Happy Chistmas.
 








 
Back
Top