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Difference between 460V and 480V regarding...

Difference between 460V and 480V regarding...

Difference between 460V and 480V regarding...

I have a piece of equipment that says it needs 460Vac, 60Hz, 3-Phase.  I have a 480Vac receptacle.  What, besides 20 volts differentiates these two?  Is 460V and 480V somewhat synonymous?  Are they one in the same as far as the motor is concerned or do I need to add a resistor to try and get it down to 460?  If anyone could enlighten me it would be a great help.  Thanks in advance.

RE: Difference between 460V and 480V regarding...

Your equipment is not going to care...

Motor manufacturers commonly state 460 volts.  Industrial power systems are 480-volt nominal, and mine typically deviate a bit on the high side of 480 volts when lightly loaded.

old field guy

RE: Difference between 460V and 480V regarding...

For various historical reasons, we have a situation where 460V is the equipment voltage rating for equipment to be applied to 480V nominal power systems.

RE: Difference between 460V and 480V regarding...

The present NEMA standard is to nameplate motors at 460V for operation on a nominal 480V system.  This allows for the unavoidable voltage drop that occurs between the main bus and the motor.

If you look on the nameplate of a nominal 120V appliance or tool, it is most likely rated at 115 V.  Same idea.  

You're OK.  

RE: Difference between 460V and 480V regarding...

ANSI standard delineates this. 480V is referred to as the "Distribution Voltage" and 460V is referred to as the "Utilization Voltage". In addition to the other reasons stated above, 460V was chosen by NEMA as the Utilization Voltage for motors because prior to any universal standards, some motors were designed for 440V, some for 460V and some for 480V. You can still see that on old motor nameplates. 460V was the "compromise" that allowed manufacturers to unify their nameplate information without necessarily changing their design.

Same with the other voltages, i.e. 220-230-240 or 110-115-120. 240V is DV, 230V is UV, 220V is old. 120V is DV, 115V is UV, 110V is old. Still to this day however, not every utility follows these standards, but the equipment is all made to work withing the ranges anyway.

Eng-Tips: Help for your job, not for your homework  Read FAQ731-376 pirate

RE: Difference between 460V and 480V regarding...

Awsome.  Thanks to all those who responded.  Greatly appreciated!

RE: Difference between 460V and 480V regarding...

Every motor should have its design voltage tolerance.

For my factory, our incoming voltage to the switchboard is 433V, but we always purchased motor that is 415V +/-10% voltage tolerance.
This is mainly to cater for voltage drop.

RE: Difference between 460V and 480V regarding...

480 volts is the system voltage.  460 volts is the rated voltage of your equipment.  460 volt rated equipment is always used on a 480 volt system to account for voltage drop due to starting or line losses.

In any event, you are fine.  No resistors required!

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