Teco 7300V weirdness

Was roped into helping a friend of my Dads with a VSD issue on a CNC routing machine. Back story is the original spindle VSD went phut, and he ended up with a Teco 7300V VSD as a replacement. He couldn't find anything else to drive up to 400 Hz at the time. Was 12 months ago, and he had it sitting beside the router using the local start / stop and local pot for reference... Worked fine.

Now he is trying to tie into the CNC controls which provided a BCD output for 6 discrete speeds. 3 wire connection to the multi speed inputs, BCD is all good, but if any speed > 300Hz is entered in any preset, the VSD will stop and go to 305.3 Hz in reverse when that preset is selected. All works fine if the preset is < 300Hz

Reverse is disabled, so no sense at all.....

Sounded mad, so disconnected everything from the CNC controls and confirmed problem using bits of wire.

Hung a pot off and selected AI as reference, no problems with 0-400Hz operation same as local pot....

Seems to be a VSD problem to me ?? Cant see any parameter which could cause this. Any ideas ??

Cheers Chris

The input might be configured bipolar with the leading bit determining direction

DickDV said:

The input might be configured bipolar with the leading bit determining direction

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I started to suggest that, but there is no new bit change for a 3 in BCD from 2, is there? Now if it were at 200Hz or at 400Hz, I could see it. It must be some direction configuration or software limit though, but I have never worked with that drive nor near that frequency.

I suppose it's possible that there is a firmware bug of some kind??
I have used several of the 7300CV's (must be a similar drive but some difference?) but I never tried anything above 120hz with them.

DickDV said:

The input might be configured bipolar with the leading bit determining direction

Click to expand...

Not as I understand it, there is a dedicated "start forward" and "start reverse" input.
The problem occurs at any BCD position, but only if the preset > 300Hz..

mendonsy said:

I suppose it's possible that there is a firmware bug of some kind??
I have used several of the 7300CV's (must be a similar drive but some difference?) but I never tried anything above 120hz with them.

Click to expand...

Becoming more convinced this is the case.. Th distributor of the VSD wasn't to interested as it had been running 12 months. Guessing cause he was a guy in a shed didn't help much either. I'll call Monday and poke them with a stick...

I will be somewhat surprised if that gets you anywhere. There are still a few distributors selling them, but Teco-Westinghouse is showing them as "legacy" products.

One thing I always do when using a "previously owned" VFD is to perform a factory reset to default values, clearing out all previous programming. That drive has a "PLC function" as they call it, which uses bit mapping of the inputs. It can get really complicated to try to use that, so people often start out trying, then give up, but leave behind bits of programming. Then because they revert to more simplistic use of IO and it works, they never bother to clear out the other stuff, and you don't know it is there until you try to do something else that causes a conflict. Trust me, it's not worth trying to chase that phantom, just erase everything and start clean.

If you did that, then it might be a bug. When Teco first released that drive it had a lot of glitches. They were eventually fixed and people could flash the firmware, but if a drive was working, most people didn't bother.

jraef said:

One thing I always do when using a "previously owned" VFD is to perform a factory reset to default values, clearing out all previous programming. That drive has a "PLC function" as they call it, which uses bit mapping of the inputs. It can get really complicated to try to use that, so people often start out trying, then give up, but leave behind bits of programming. Then because they revert to more simplistic use of IO and it works, they never bother to clear out the other stuff, and you don't know it is there until you try to do something else that causes a conflict. Trust me, it's not worth trying to chase that phantom, just erase everything and start clean.

If you did that, then it might be a bug. When Teco first released that drive it had a lot of glitches. They were eventually fixed and people could flash the firmware, but if a drive was working, most people didn't bother.

Click to expand...

I didn't reset it to defaults, but the owner did...Maybe worth seeing if a later firmware is available..

Try setting parameter 15-6 to 1112. That should clear any stray PLC programming that might be lurking in it.

mendonsy said:

Try setting parameter 15-6 to 1112. That should clear any stray PLC programming that might be lurking in it.

Click to expand...

Thanks, will pass on...