3 phase voltage

[jethrow]

As stated in an earlier post, we have a new piece of equipment that is powered with 3 phase. It has a 20HP motor rated @ 208-230V. We just finished having the power company run the 3 phase service to our shop. I tested the voltage and have 120V from GRN to BLK and RED, 211V from GRN to ORG, 242V from BLK to ORG and RED to ORG and 240V from BLK to RED. I recognize that ORG is what is referred to as a 'high leg' and as long as the machine is connected properly should not be a problem. What I'm concerned with is the 230V rated motor being connected to a 240V service. Should I be (concerned)?

tia
J

 

[bphgravity]

Re: 3 phase voltage

No, this is not a problem. See the wording at Table 430.150 of the NEC:

The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.

 

[Saferguy]

Re: 3 phase voltage

The motor should be fine. You're slighly less than 10% above the motor rated voltage.

 

[charlie b]

Re: 3 phase voltage

You'll drop a few volts between the supply point and the motor itself. The impact on the motor will be that it runs with a lower current, and therefore a lower temperature. That is not a bad thing.

But the motor's voltage rating is based on the ability of its insulation system to prevent leakage current from the conductor to the case. You need to take a close look at the manufacturer's information. If it explicitly states that the motor shall not be operated above 230 volts, then you will have to take some remedial action. If it does not, then I would agree with Bryan and Saferguy, that it would not be a problem.