VFD and AC motor rating

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JaQ

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Gents

I came accros a 'small' problem, I was trying to find some info online but no luck.

I don't have much experience with VFD'S.
At the moment I have AC 3-phase electric motor controlled by VFD, motor is rated at 375kW.

I need to install new motor but motor is rated at 1120Amp (858kW-1150HP).
The motor application is way over sized, I will need max 600HP (max rating for pump, which motor will be driving)

What kind of option I have? Do I need to change VFD'S?? Could I de-tune setting in VFS to deliver less current?

Thanks in advance

Jack
 
Greetings JaQ, and welcome to the forum.
Can you provide information on the VFDs in question?
You might also contact the VFD manufacturer's technical support group and see what answers they can provide.
 
JaQ said:
Gents

I came accros a 'small' problem, I was trying to find some info online but no luck.

I don't have much experience with VFD'S.
At the moment I have AC 3-phase electric motor controlled by VFD, motor is rated at 375kW.

I need to install new motor but motor is rated at 1120Amp (858kW-1150HP).
The motor application is way over sized, I will need max 600HP (max rating for pump, which motor will be driving)

What kind of option I have? Do I need to change VFD'S?? Could I de-tune setting in VFS to deliver less current?

Thanks in advance

Jack
Click to expand...

If you need 600hp that's around 450kW.
Is the VSD rated for that?
What is it's rated current?

You could reduce the v/f ratio and that will reduce the motor current if it is running below its rated power. Some inverters have a pump curve v/f ratio that can be selected.
A few more details would help us help you.

So where in Scotland if you don't mind me asking?
I'm a Scot and know the country quite well.
 
Besoeker said:
If you need 600hp that's around 450kW.
Is the VSD rated for that?
What is it's rated current?

You could reduce the v/f ratio and that will reduce the motor current if it is running below its rated power. Some inverters have a pump curve v/f ratio that can be selected.
A few more details would help us help you. ...
Click to expand...
Yes, as he points out: if your existing motor is 375kW, most likely your drive is rated for that as well. But if, by luck, your drive is over rated for 450kW, it might work. You can in essence tell the drive to limit the output going to your new 858kW motor to 450kW. That will limit the speed at which it can run as well (to about 53%), so you must understand all of the interactions and consequences this entails. But this is done quite often as an emergency solution when a motor is bigger than necessary.
 
Thanks Gents for info...

I will get info about VFD next week, then I will see if this will work.

Besoeker

I'm living in Aberedeen:)
 
JaQ said:
Thanks Gents for info...

I will get info about VFD next week, then I will see if this will work.
Click to expand...
OK, good.
Sounds like a custom application with a non-standard voltage.
Is it off-shore by any chance?

JaQ said:
Besoeker

I'm living in Aberedeen:)
Click to expand...
The granite city.
I went to school in Kirriemuir,a bit further south. I suppose it's main claim to fame is being the birthplace of James Barrie, the creator of Peter Pan.
 
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