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Abner
07-28-2016, 07:38 PM
Hi,

I have a TECO 3ph VFD. It has worked great for years.

Now it just quits. was making a 3/16 keyway in 3/4 CR steel and it just quits. Lights off no power. If I let it sit for a few hours it will likely work again...for a short time. This would seem like an over heating issue but I don't know what to test for or where.

What should I be looking for?

Thanks,
Abner

macona
07-28-2016, 07:40 PM
Something in the internal power supply is not happy. Could be as simple as a cold solder joint but really, that does not happen very often any more. Unless you know electronics you are probably better off just buying a new one.

J Tiers
07-28-2016, 08:15 PM
Something in the internal power supply is not happy. Could be as simple as a cold solder joint but really, that does not happen very often any more. .....

Happens more than it used to, before lead-free solder.

Replacement is the best bet for you, yes.

It is probably repairable, but if it was a good thing for you to try, you would have posted about the one little solder joint that failed and had to be fixed. You would not have posted about the dead VFD.

Probably NOT overheating, likely just something warming up normally and opening a broken connection.

PStechPaul
07-28-2016, 08:18 PM
Most newer VFDs are not much user-repairable, but you could check for proper operation of the cooling fan, and for dust and debris in the cooling path. Beyond replacement of the fan, or perhaps the large capacitors, most of the electronics is modular and designed for replacement as a module. Here's the guts of a Hitachi VFD I tried to repair - the problem is a shorted IGBT in the module, and it was difficult to unsolder:

http://enginuitysystems.com/pix/Hitachi_VFD_0811_800p.jpg

http://enginuitysystems.com/pix/Hitachi_VFD_0812_800p.jpg

http://enginuitysystems.com/pix/Hitachi_VFD_0813_800p.jpg

I also have a large Toshiba VFD that I thought was defective, and I even tore it down to get at the IGBTs in the module. But it was actually OK, and just set up wrong, so I got it working.

http://enginuitysystems.com/pix/electrical/VFD_Toshiba_2025.jpg

I made a movie:


https://www.youtube.com/watch?v=cW5Nk9yJXkI

CalM
07-28-2016, 10:17 PM
Check the fault code

J Tiers
07-28-2016, 10:36 PM
Check the fault code


Hi,
... Lights off no power. ...

And, so, no fault code.

MIGHT be able to look at the fault history if it stays on long enough to navigate there. Most keep the last 4 in memory (non-volatile memory) for debug purposes

Quite possible it will not record one if the control power fails, it may not have a code for that, it might just show "UV" or whatever the code is for undervoltage, which it will show for a normal turn-off anyway.

Abner
07-29-2016, 07:49 AM
Ok , I will open it up and take a look for something obvious like a cold solder joint. Stops like you turn off a light switch.

Tough on small endmills during powerfeed. :(