Boosting voltage with a transformer

Guidelines for increasing voltage through the use of a transformer. January 31, 2001

Q.
I have a glu-all machine that requires 480-3 phase power. I got a bid from the electric company and they wanted over $8,000 to run 480 to my building. Does anyone know about using a transformer to boost the voltage to 480?

Forum Responses
Most machines can use transformed power. Be sure that any variations in the input power, which will cause variation in the output power, fall within the 10% allowance that most machines require. This means that a 480 volt system can only handle + or - 10%. Some machines will not accept this much voltage variation.

I have used transformers many times with no problem. The installation of a voltage stabilizer is suggested.

Dave Rankin, forum technical advisor

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You can use a transformer with the corresponding primary and secondary voltage system. Just be sure that the rated output of the transformer (given in kVA) is at least by ca. 20% higher than the power input (demand) of the consumer(s) in kW. To get kW, multiply HP by 0.75; e.g. 10 HP motor has power output 7.5 kW. The equation would be: 1HP=0.75 kW.

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The incoming power at your electric service must be 3 phase. If it isn't, you need to have a voltage inverter, or to change the motors to single phase. Either way, it will be expensive.

If your service is 3 phase, determine if it is large enough to handle adding the machine. How many amps is your machine rated for? What size in amps is your service? How many and what size breakers are in your service panel now?

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3 phase transformers are expensive. Another way to do this is to buy 3 single phase machine tool transformers and connect them together as one 3 phase unit. I have done this several times for customers and it works very well. I suggest that you have a competent electrician do this hook-up for you.