Motor voltage rating different than nominal

[hopemoon]

Hi,

I want to know if there is a numeral into the Electrical Code that allows motor supplies with a different voltage that the nominal? For example, can a 460V specified motor be run on a 480V mains supply or the other way round?


How does it affects my cable? I mean, I should calculate the cable with the voltage supply (480 V) or with the nominal voltage (460V)?


Which is the current value that I have to use to the MCC load summary? The nameplate power affected on 480 V or?

Thanks in advance!

 

[petersonra]

Hi,

I want to know if there is a numeral into the Electrical Code that allows motor supplies with a different voltage that the nominal? For example, can a 460V specified motor be run on a 480V mains supply or the other way round?


How does it affects my cable? I mean, I should calculate the cable with the voltage supply (480 V) or with the nominal voltage (460V)?


Which is the current value that I have to use to the MCC load summary? The nameplate power affected on 480 V or?

Thanks in advance!

You always use the FLC values from the charts in the NEC.

480V is nominal. 460V is maybe what the motor is designed around to account for some voltage drop.

 

[hopemoon]

You always use the FLC values from the charts in the NEC.

480V is nominal. 460V is maybe what the motor is designed around to account for some voltage drop.

So I calculate the running Voltage Drop according to:
Vd = (C * FLC * L * Z ) / 1000


And the % Permissible Voltage Drop
Vp% = (100 * Vd) / V


V = (motor rating voltage = 460V) or (supply voltage = 480V)??

Thanks.

 

[hurk27]

460 is a normal voltage rating for a motor designed to be run on a 480 volt system, take a look at this NEMA chart for motor ratings of different nominal system voltages:

Table 430.250 is the table you use for the FLC