msteph

I have to build some control panels that will be going to India. The utility voltage in India is 420 volt 50 hz. I have existing 480 volt 60 hz equipment here that has been bought and will be sent to India. I have to make the equipment bought here work in India. I know I need a step up transformer to get my voltage up, my question is about the frequency change. Would it be better to change the hz before the primary side of the transformer or after the transformer. I have a total load on the load side of the transformer of 385 amps. Any help would be greatly appreciated.

John Valdes

You can change the voltage with a transformer but you can't change the hertz. You are in a pickle.
The transformer you require will not be a stock model. You need a custom built transformer to go from 480 to 420.
You will need a converter to change the frequency. How much equipment do you have and what is it. Do you have an idea of how much power you will need.

If your equipment is new, the motors may be already set for either 50 or 60 Hz. But most likely the voltage will be 380/460.
Give us the description of each piece of equipment. If it's only motors we can fix you up real easy like.

Ps.......Whos the dummy that bought the equipment?

Toronto Sparky

Any timing devices or cpu in those controls?

__________________
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ElectricArcher

You stated you have to build control panels, are they controlling motors? If so, are the motors already their? Wouldn't he need a transformer from 420 to 480.

miller_elex

I would bet that VFD's will operate just fine, as would anything else that rectifies AC, cleans up the DC, then inverts it back to AC.

Check the tolerances on the power supplies. You will be surprised how much garbage power they can accept.

The downside, is that rectifiers further deteriorate the power quality situation, unless they are of the expensive, high power-factor variety.

The harmonics that three-phase rectifiers send back up the line side can put serious heat in the transformer windings. Don't ask me how much, I'm no engineer, but there are formulas for that stuff.

msteph

The equipment is a 90 ln ft combination of grinders, separators, glue spraying and pressing machines with mostly 480 v 3 phase motors. However there are several 480 v electric heating elements in a oven unit controlled by thermal couples. All the control voltage is 120v 60 hz in the control panel now. I would say the equipment is 10-12 years old. There are a few timing devices/counters on the over all set-up. The new owners (from India) ask if we could change the voltage and hz before the control panels so they would only have to make a single point connection once the equipment is reassembled. The transformer is no problem, and I have got that taken care of. It is the hz difference that I am not sure how to address.

John Valdes

Yes, you can do as they ask. They are going to spend a mighty dollar for a rotary converter to run all this equipment. But, if they want it, start getting quotes for the complete system.

No issue with the heating elements or control. Make sure all control devices can work with 50/60 Hz. I am fairly sure they are listed for both but not absolutely sure. Just check nameplates on everything. And make a list.
You can buy motors that are listed 230/460 @ 60 HZ and 380/415 @ 50 Hz. Check the motors you have.
As said above a VFD for each motor will solve all the motor issues.

You also can run the 460 volt motors on 412 volts until they crap out, then let them get replacements in India. I did this 10 years ago for Caterpiller and the motors are still running. If this is your company in India, this may be a good choice. Just run them. Size would be the determining factor.

I wish you good luck. You have to make some decisions. If I were in your position I would make the machines work. Not buy a very expensive rotary converter.

miller_elex

What about synchronous speed??

msteph

Owners have desided to use a rotory conveter. If any of you have to price one of these things, take a seat before they give you a price. Thanks for thehelp guy's.

John Valdes

I know what they cost. That's why I spent my time trying to help you get around the rotary converter.
I had a customer one time that supplied most of a decent size manufacturing facility with two of them.

RIVETER

There is something that you may not get involved with but I had to build 5 panels destined for South America. I was told upon completion to scratch them up a bit knock a few holes in them, etc. The reason was something about a different taxation on used verses new equipment. Go figure.