Thread: Any Electrical Engineers out there who can explain something?

Hi Guys,

All was well with my grinder and the world until the other day when I heard a 'BANG' as I was grinding a blade.

I suspect that metal dust had got into the VSD (Controller) and shorted it. Sure enough when I disconnected everything and looked inside there were come blackened components.

Now the fun starts in trying to source a replacement.

My motor is 380 Volt 3 Phase (please see plate below)


My current VSD label states:
240 Volt Single Phase Input (Standard New Zealand and UK Power)
240 Volt 3 Phase output
Label Below:


If my motor is 380 Volt, how did this work - or is the 3 Phase the key - the VSD was working fine until the dust issue.

Do I not need a 240 Volt Single Phase input/380 Volt 3 Phase Output VSD?

Some suppliers say 240 Volt 3 phase output is fine, while others say 380 Volt 3 Phase Output.

Any advice appreciated.

Good question.

This is the first thing that came up in my search for an answer.

https://electronics.stackexchange.co...n-on-220-volts

I don't understand much of that!

Good luck and I will be lurking.

Thanks for that 32t,

You would think that an IT Project Manager would have tried Google :-)

Like you, I don't really understand a lot of that article, but it seems to indicate that my VSD/VFD output of 240 Volt 3 Phase is OK.

Originally Posted by 32t

Good question.

This is the first thing that came up in my search for an answer.

https://electronics.stackexchange.co...n-on-220-volts

I don't understand much of that!

Good luck and I will be lurking.

Many/most VFD/VSD will take single phase power and generate the third phase for 3 phase output. They can also take 3 phase power in and give 3 phase power out.

Does this answer your question?

Hi Robini,

Thanks for that. It was more the fact that my current VFD has an output of 240 Volts when my motor is 380 Volts?

Originally Posted by Robini

Many/most VFD/VSD will take single phase power and generate the third phase for 3 phase output. They can also take 3 phase power in and give 3 phase power out.

Does this answer your question?

From what I remember when researching this for work, motors can (but not all) have a low and high speed connection. 220V for low and 380 for high. You just have to wire it correctly, typically there is a wiring diagram printed on the cover for the connections on the motors we use. I would buy something with the same specifications and rewire the way it was, it worked before and didn't burn your house down.

dinnermint, you are exactly correct. All 3 phase motors I have worked with can be wired to different voltages, just pay attention to the diagram and your golden.

Good point - My workshop is a wooden shed, so even more risk, but yes, it didn't burn down :-)

Originally Posted by dinnermint

From what I remember when researching this for work, motors can (but not all) have a low and high speed connection. 220V for low and 380 for high. You just have to wire it correctly, typically there is a wiring diagram printed on the cover for the connections on the motors we use. I would buy something with the same specifications and rewire the way it was, it worked before and didn't burn your house down.

Originally Posted by Robini

dinnermint, you are exactly correct. All 3 phase motors I have worked with can be wired to different voltages, just pay attention to the diagram and your golden.

Great, so I'll just go for a 240V Single Phase Input to 240V 3 Phase Output and wire as before.

Good thing I didn't go for a 380Volt output of the motor would have took off like a jet..

Many thanks guys.

It also depends on what notation is used: whether they measure between phases or between a phase and the neuter.
My house is wired for 380, which means 380 when measured from phase to phase, or 230 when measured between each phase and the neutral line.