RE: [CAD_CAM_EDM_DRO] Re: Dead VFD

> From: jmkasunich
> Sent: Monday, November 24, 2003 8:32 AM
>
> ....
> The only fix I can recommend would be to replace the entire
> module with an identical one (if you can find one). The
> manufacturer and part number of the module should be printed
> somewhere on it.

We found an exact replacement. Not cheap but cheaper than a new VFD.

> ....
> Not likely. Most likely causes of failure:
>
> 1) switches or relays in the output leads
> 2) shorts or other wiring problems in the output leads or motor
> 3) high DC bus caused by trying to stop a large inertia load
> 4) misc...
>
> the drive _should_ be able to protect itself against 3 and
> probably 2. Number 1 is a drive killer - never open the
> motor leads when the drive is running.

My friend thinks that the VFD failed when he did a stop and then a restart
before the spindle had come to a stop. But I don't see how this would have
caused a problem because, on my VFD at least, all this causes is a ramp down
'till you hit start again and then a ramp back up.

He suspects that he needs to add a braking resister ...

Cheers,

Chuck Hackett
"Good judgment comes from experience, experience comes from bad judgment"
7.5" gauge Union Pacific Northern (4-8-4) 844
http://www.whitetrout.net/Chuck