Rated Motor Voltages....Why do we do it that way?

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frizbeedog

frizbeedog

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What are the main reasons and/or benefits of using these voltages for motor ratings as listed in tables 430.248 and 430.250?

115, 200, 208, 230, 460......

...with 208 seeming to be the only voltage on target.

Thanks,

Brian.

:)
 
frizbeedog said:
What are the main reasons and/or benefits of using these voltages for motor ratings as listed in tables 430.248 and 430.250?

115, 200, 208, 230, 460......
Click to expand...

Because no one made the motor manufacturers do it differently.:smile:
 
I thought is was due to root mean square of the voltage, except for 200 & 208 V???, 5 % or less works for most of these numbers.

115, 200, 208, 230, 460......

verses the base line of (number - 5%)

120, 240, 480.

Ex:
So if they built a motor to the minimum of 115 volts they'd be there!
 
cadpoint said:
I thought is was due to root mean square of the voltage, except for 200 & 208 V???, 5 % or less works for most of these numbers.

115, 200, 208, 230, 460......

verses the base line of (number - 5%)

120, 240, 480.

Ex:
So if they built a motor to the minimum of 115 volts they'd be there!
Click to expand...

208 is (sqrt3)*120 ... so

120/208/240/277/480/600 all "correlate"
115/200/230/???/460/575 are the "nominal" (never seen one for 277)
 
GeorgeB said:
208 is (sqrt3)*120 ... so

120/208/240/277/480/600 all "correlate"
115/200/230/???/460/575 are the "nominal" (never seen one for 277)
Click to expand...

120/208/240 120/208/240 as single phase and 208/240 only three phase motors.

277/480/600 277V is not used as single phase motors are not made for this utilization voltage level.
 
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