# 480V VFD running on 380V?



## hein (Feb 18, 2019)

Hello forum,


I have a client who imported a Powerflex 70 VFD (7.5kW) from Australia. The Australian 3-phase voltage ranges from 415 - 480V, 50Hz. Here in Africa we run on 380V 50Hz.


In the manual it mentions under File E, Drive Memory Group, item 202:


"[Voltage Class]Configures the drive current rating and associates it with the selected voltage(for example, 400V or 480V). This parameter is normally used when downloading parameter sets."


Would this setting allow the VFD to run on our 380? Is this even possible? Or is the only option a step up transformer?


Thanks in advance,
Hein


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## JRaef (Mar 23, 2009)

The drive will accept 380V, no problem. But the output voltage will be limited by that as well, standard VFDs cannot provide an output voltage that is greater than the input voltage. So if your motor is designed for 480V, you will end up with a limited speed or a loss of torque. If the motor is designed for 400V however, 380V is within the typical tolerance band for full output.


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## micromind (Aug 11, 2007)

What JReaf is getting at here is all motors have a Volts/HZ ratio. 

If, for example, the motor is 460 Volts and 60 HZ, it won't do well at 380 Volts and 60 HZ but it'll do fine at 50 HZ. 

You might need to limit the max HZ in the VFD program.


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## Abenr (Apr 2, 2019)

You can use it, but there are two ways to use it

1. When the motor operating frequency is less than: 50 380/480 = 39.6hz, the motor can meet the constant torque operation. At this time, even though the power supply is low, the constant flux of the motor can be maintained by changing the frequency year on year, so the maximum torque is not lost

2. When the motor is to operate between 39.6-50hz, the power supply voltage is less than the rated voltage of the motor.

Therefore, the motor runs in weak magnetic field, and the maximum torque decreases, and the proportion of decrease is about 1- (380/480).

^ 2 = 37%


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