Supply Voltage

I wish we had that problem. On some days we're running a huge engine/transmission manufacturing plant on 420 vac which is just at about at the lower end of the usual 10% under-voltage recommendation.

Perion

There is an ANSI standard (C84.1) for acceptable voltages. 250V is only 4% high, assuming a 240V service. Most utilities/public utility commissions in the US allow either +/-10% or +/-5% for industrial customers (or some combination like +5%/-10%). Either way, +4% is not bad.

ANSI allows the following on a three wire, three phase, 240V service: Max.

You might also check with the local utility. The tariff that the customer operates under will likely spell out the voltage limits. If the utility is operating within these limits and the customer wants better regulation, the customer must provide that regulation.

Charles Perry P.E.

| Is there any problem with excessive voltage for standard type | equipment (motors)? | | If it is a problem, what's the best solution? | | Someone is reporting 250VAC coming into their production facility. | | I had it in my head that 15% variance was acceptable, but there's | quite a bit in my head that's not necessarily correct!

Since I don't know whether you are referring to a 240 volt circuit or a 277 volt circuit, I did the math on both.

The above used way more precision than actually necessary for this. But you get the picture.

-15% of 240 is 204

-15% of 277.128129211 is 235.558909829

So what _should_ you be getting?

FYI, I think 15% is too extreme.

On Wed, 27 Oct 2004 10:20:19 -0400 Perion wrote: | I wish we had that problem. On some days we're running a huge | engine/transmission manufacturing plant on 420 vac which is just at about at the | lower end of the usual 10% under-voltage recommendation.

Maybe someone needs to tweak the tap on your incoming transformer. Maybe you can get the power company scheduled to do that at your next plant idle period (most likely is it not a load-changeable tap).