# 460V motor on 400V 60HZ?



## mikey383 (May 21, 2012)

At our facility, we have a couple pieces of European equipment that run on 400V @ 60HZ. There's a large 480V to 400V transformer feeding them.There's a belt conveyor on the exit side of the one machine that a project engineer is wanting to replace, due to some issues with parts and availability. The problem is that he bought a new conveyor with a 1/2HP 460V 1755 RPM 60HZ motor. Currently, it is a 1/2HP 400V 1670 RPM motor. 

I've tried unsuccessfully to talk the engineer into swapping the motors from the existing conveyor to the new conveyor and gearbox. He's dead set on using the new 460V motor. 

I noticed there's a small Danfoss FC51 VFD on the existing motor. Now I understand that I won't be able to get anything higher than 400V RMS out of this drive, and 400V is outside of the 10% tolerance window, but would it be safe to try to run the 460V motor on this drive if it's not running at 60HZ? The only thing this conveyor is going to have on it is empty one gallon plastic bottles, and only 6 of them at a time. 

Aside from that, the only other thing I can think of is to install a 400 to 480V transformer in the machine somewhere.


----------



## chrisfnl (Sep 13, 2010)

Is there a reason you can't run the 480 to it?


----------



## mikey383 (May 21, 2012)

chrisfnl said:


> Is there a reason you can't run the 480 to it?



In all actuality, no. I could have this motor fed with 460V from an adjacent machine in virtually no time at all. 

The problem with that is having the controls being fed from one machine and the supply voltage being fed from another machine. IMO, that's a bad practice. If this motor was controlled by the plant PLC out of one of our MCCs, I'd be fine with it, but it's not.


----------



## micromind (Aug 11, 2007)

Operating a 460 volt motor on 400 volts is very much like a 230 volt motor being supplied with 208. 

Unless it's heavily loaded, it'll run just fine. 

Since it's on a VFD, you could program the max HZ to something like 55 or so and it's almost certainly be ok.


----------



## Pfaffel (Dec 18, 2014)

I agree with micromind, just check your running current at full load. If you cook the motor it just means your engineer gets a second chance to order the right motor 


Sent from my iPhone using Tapatalk


----------



## mikey383 (May 21, 2012)

micromind said:


> Operating a 460 volt motor on 400 volts is very much like a 230 volt motor being supplied with 208.
> 
> Unless it's heavily loaded, it'll run just fine.
> 
> Since it's on a VFD, you could program the max HZ to something like 55 or so and it's almost certainly be ok.


Thanks. That's what I was thinking, I just wanted another opinion.

The only load on this motor will basically be the gearbox and conveyor belt. At that, it's only an 8" wide x 60" long belt, so I can't imagine the motor will even see much of a load at all. Plus, for all I know right now, the VFD could be set at 30Hz. I didn't get much time at all to check through the parameters when I was scoping out the project. It was basically "Yep, it's on a VFD. Close it up, you're holding up production."


----------



## JRaef (Mar 23, 2009)

So what you have to be most careful about is the programming of the motor data. The existing 400V motor is likely set up as 400V 50hz, so the V/Hz ratio coming out of the drive is 8:1. For a 460V 60Hz motor, that needs to be 7.6:1 to avoid saturation and unnecessary heating of the motor. So just reprogram the drive to what the new motor is, 460V 60Hz and it will adjust. You are right, your upper speed limit will be limited, but only IF you want full torque at 60Hz. What will happen due to the 400V limit is that if you go up to 60Hz, the motor will run out of voltage at around 52Hz, so after that, the torque will start to drop. If you never run at speeds that high however, you will never notice.


----------

