Looking for schematic for well pump controller

[Art Todesco]

We have a community well here serving several houses. The whole thing is pretty fancy. The pump is a 3 phase unit. There is no 3 phase in the subdivision. But, the controller 'makes' 3 phase and supplies the pump with 40 to 70 Hz depending on the demand. As there are now few houses on that well, it's probably running at the 40Hz frequency. The controller is a Franklin Electric SubDrive 300. I called Franklin Electric and they wouldn't provide a schematic as it is a "throw-away" device. Excuse me, it's a $2500 throw-away device! BTW, they won't fix them either ... only sell you a replacement. Kind of reminds me of Behringer audio equipment. Anyway, the unit has already been replaced and I have the old unit. I would like to fix it for a future breakdown. Has anyone dealt with these units? Any tips would be greatly appreciated. I know that these type of circuits, basically akin to a switching power supply, can be tricky to troubleshoot. Thanks.

[Dean Hoffman]

You might give the alt.engineering.electrical group a try.

[gfretwell]

Even if you had the schematic for that VFD, you might have a problem sourcing parts.

[dpb]

Looked at the PFD on the unit; that is pretty fancy for the purpose, indeed. I'd wager you'd not really notice the difference if simply replaced it with a conventional system going forward.

I note there are some diagnostics; do you have any indication of what the failure code(s) were, if any, when that unit was removed? Be a start, anyway...

[Tony Hwang]

Ditto, some maybe ASIC stuff which is impossible to get. Once I have to jury rig an ASIC with several ICs on my ham radio gear. They have part no. but they are not listed any where.

[KLayton888]

Try posting to sci.electronics.repair

Sounds like the thing is basically a "rotary phase converter" in order to generate a fake 3 phase.

[gfretwell]

Except there are no moving parts

[Don Y]

You haven't indicated the failure mode. Chances are, one of the FETs in the output drive is dead (you'd need a 'scope or DMM to start). If it is just behaving "really weird" (for sufficient values of "weird"), it could be something as simple as failed electrolytics.

What is the environment like where the controller is normally located? Can you smell any "burnt" odor? Is the controller potted?

[trader_4]

And for the replacement one, I hope there is good, properly installed surge protection. Lightning surges are a frequent source of failures on that type of eqpt. A $100 surge protector could save spending big bucks again.

[Art Todesco]

A simple replacement would be nice, however, the pump motor itself is 3 phase and there is only single phase available. So the pump would have to be replaced. Also, the unit was pulled by a local well drilling company, so I don't know what the error codes might have been. They only know to replace and junk the old unit. Other than removing the top, I haven't looked inside yet.

[Art Todesco]

That sounds like a good suggestion, moving forward. The unit is located, not at the top of a mountain, but maybe 85% of the way up, so it and its associated power lines, could be more vulnerable to lightning strikes. The lines themselves, are underground, but the transformers, etc., of course, are above ground. Presently there are no houses in that part of the subdivision, however, the power infrastructure is there.

[Art Todesco]

Good idea, I'll try posting to some of these other sites.

[dpb]

...

...

Or with just a conventional converter...

But, unless this is a really large well, swapping out the pump the next time instead of the controller may be no more expensive at the time and be less maintenance/expense going forward by far...

Just the thought that strikes me having been on a well for almost entire life I don't see there's any difference between a conventional pressure tank system and "city water supply" to be worth such an additional complication/expense as that controller.

Just how big a well and water system is this, anyway?

[Dean Hoffman]

I've seen the aftermath of lightning hitting the ground. It had actually bored a hole in the ground to an underground wire that was bad. The wire was about 30" deep. There were maybe fifteen or twenty corn plants surrounding the hit that were yellow. The rest of the field was green. I thought the part about corn plants being burned was just an old farmers' tale. It wasn't.

[gfretwell]

Lightning seldom actually hits the stuff it blows up. You are protecting from transients on the power line and it is usually a difference between the ground at the panel and the ground at the equipment that kills you. Make very sure that your lightning protector is connected to the well casing or, if it is plastic, drive a rod or two right there.

[micky]

I heard on the radio recently that lighting, at least at the bolt, is twice as hot as the surface of the sun.