Vfd On A Millrite

M

mikegt4

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I use a FM50 VFD to run my Millrite, I have used it for about 5 years. The motor is a GE pancake of about 1 hp (the machine is about 25 miles away so I can't be certain). The VFD is 220/1ph input, 220/3 ph output. I have it set up to utilize the original drum switch, FWD OFF REV. It has always worked well but it has the annoying habit of starting to turn in the direction that I select but immediately reverses direction and rotates at a very low speed. If I switch it back to OFF and restart it it will run fine. Sometimes it takes cycling the switch 2 or 3 times before operating correctly, other times it starts normally without any "shutter".
Back when I was researching VFD' s I recall someone on a forum had the same problem and a solution was posted. IIRC it was a setting in the VFD parameters but I don't remember what it was. It is just an annoying problem that I would like to fix. Any suggestions
 
Mike did you ever solve this and if not is your drum switch connected between the vfd and the motor?
Mark S.
 
The problem still remains although not as prevalent recently. The drum switch is not between the VFD and motor, it is used as a remote switch and wired per VFD instructions.
 
That's a weird problem. I've never seen a Teco VFD in real life so I don't know what I'm talking about, BUT....
I have experience with a lot of other VFD make/mfg and I've never seen that.
To me it sounds like a software glitch. Some failure to resolve speed/direction and getting stuck in a never ending loop.
If the drive has a serial or USB interface for connecting a PC, I would check the Teco website for firmware updates and see if there's a fix for it.
If that didn't pan out, I'd try re-tuning the drive if it has an auto tune feature.
If that was a bust too, I'd record all the modified parameters, reset the drive to factory defaults, and re-enter the modified parameters.
 
Yep it might need a software update- since it obviously is working and has been acting in a (sort of) predictable manner.
Mark S.
 
As far as I have seen, VFD's operating programming is not updatable by software download. There is also no provision on these VFDs to connect to the computer. I would check to see if there are any error codes, do a VFD programing reset, check that you do not have an intermittent connection, and if all else fails try to use a different direction switch. It may be bad contacts in the drum switch, especially if it was previously used for high voltage and the contacts where burned.
 
OK here's another idea: maybe the switch and wiring are picking up rfi (radio frequency interference)? maybe need shielded cable and/or very small bypass caps (.01 uf) on each leg to ground..could also try a snap on ferrite suppressor near the vfd unit instead
MS
 
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