Ancient Best 10KVA UPS

[Warren]

Hi,
I am looking for any "lore" (schematics, experience, memories, etc.) that can be had about the low battery dc voltage detection circuit in my unit, a Best Model B610010KU Uninterruptable Power Supply from the 1990s. (I understand such units are still in widespread service today in the United Kingdom.) Specifically, after several years of trouble free operation, I have had to replace the batteries and found, after replacement, that it "thinks" the nicely-charged batteries (a 265v stack) has a voltage lower than its "cut out" threshold of 240v. This problem persists despite tests that show a rock solid 265 volts on the dc battery bus, even under a test load of a few amps. Since this unit is not only useful at my home, but is also a classic piece of electronic artwork, I would really like to restore it to normal operation. Any help any of you can provide in identifying the likely circuitry of the low dc voltage threshold detector and its location will be gratefully appreciated.
Warren

 

[hevans1944]

There is an online user's manual available here, but no schematics. Suggest you try to contact the manufacturer, Best Power, a subdivision of SPX Industries which has apparently been absorbed by Eaton. Here is a web page from Eaton that allows you download a PDF copy of the user's manual. Eaton also has a recommended replacement, but it is doubtful that the circuitry is the same. I think your best bet is to try to locate and contact a human at Eaton who might have access to the technical documentation (schematics, etc.) and can copy and e-mail you a copy. Or maybe they can steer you toward someone who has this information, probably retired or deceased by now, but if still alive they might be willing to help. Other than that, it looks like a good bit of "reverse engineering" is required to troubleshoot and repair your UPS. Good luck finding parts though. Are you up for the challenge?

 

[Warren]

There is an online user's manual available here, but no schematics. Suggest you try to contact the manufacturer, Best Power, a subdivision of SPX Industries which has apparently been absorbed by Eaton. Here is a web page from Eaton that allows you download a PDF copy of the user's manual. Eaton also has a recommended replacement, but it is doubtful that the circuitry is the same. I think your best bet is to try to locate and contact a human at Eaton who might have access to the technical documentation (schematics, etc.) and can copy and e-mail you a copy. Or maybe they can steer you toward someone who has this information, probably retired or deceased by now, but if still alive they might be willing to help. Other than that, it looks like a good bit of "reverse engineering" is required to troubleshoot and repair your UPS. Good luck finding parts though. Are you up for the challenge?

Thanks for your interest in my quest. All of your ideas are good, and I have already pursued most of them. I downloaded the user's manual sometime ago (when I first installed the unit). While it is helpful, it does not contain the fine detail I need now.

 

[hevans1944]

... While it is helpful, it does not contain the fine detail I need now.

So you are left with reverse engineering the UPS. Is that within your skill set?

 

[shrtrnd]

It's been a lot of years, but you have an 'ancient' UPS.
I remember the models I used to work on, I had to reset the value on the Low Battery Detection circuit after I
changed the batteries. I doubt they'd mention that in an Operator Manual. Check if you have any information
in any references you might be able to find about what-all needs to be done when you change the batteries.
Sorry I can't be more help, but your post triggered that thought in my memory banks (also ancient).

 

[Warren]

Thanks, Shrtrnd, for your interesting and potentially very helpful hint. I sure appreciate you taking the time to think about my quest and to write your message.

Can you possibly tickle your memory a bit more? Any recollection of how the reset was done? Details of the type of circuit involved? Location of the board it resides on? Or, on another tack, any colleagues who might also be "in the know?"

Warren

 

[shrtrnd]

I worked on several different models in the past, they all had their own procedure.
I just Googled 'Resetting Low voltage on Best B610010KU UPS', and went to the
site 'User Manual Powerpack SE Series 1-10KVA'
You've got to scroll down and check the different selections.
Near as I can tell on your model, you need to put a Low Voltage load on L1-N1 & L2-N2, and a High Voltage Load on L1-N2 to begin the adjustment.
Sorry I don't have time to read-trough everything for your model, but maybe you do(?).
Google is great for localizing specific information if you use the right key-words.
It's a little annoying to me that I forgot so much about resetting these things after changing the batteries, but I've worked
on so many different types of equipment over the years, I've forgotten more of the alignment procedures than I have
left time in my life to learn new ones.
Hope you find exactly what you need quickly. good luck.

 

[Warren]

I worked on several different models in the past, they all had their own procedure.
I just Googled 'Resetting Low voltage on Best B610010KU UPS', and went to the
site 'User Manual Powerpack SE Series 1-10KVA'
You've got to scroll down and check the different selections.
Near as I can tell on your model, you need to put a Low Voltage load on L1-N1 & L2-N2, and a High Voltage Load on L1-N2 to begin the adjustment.
Sorry I don't have time to read-trough everything for your model, but maybe you do(?).
Google is great for localizing specific information if you use the right key-words.
It's a little annoying to me that I forgot so much about resetting these things after changing the batteries, but I've worked
on so many different types of equipment over the years, I've forgotten more of the alignment procedures than I have
left time in my life to learn new ones.
Hope you find exactly what you need quickly. good luck.

Great keywords!. I followed up your suggestions, found the SE Series manual you directed me to and homed in on the "Low Voltage of Battery Setting." Along the way, I was fascinated (although not surprised) by the similarity of these later UPSs to my Best B610010KU unit. The fact that the SE UPS has the low dc voltage cutoff being programmable from the panel is one clear advance from my unit in which it is hard wired. I have to locate the circuit that contains that voltage reference and somehow repair or disable it. Currently my eyeball and camera-based circuit tracing is trying to find it on the board that contains the battery charger (on the battery side of the main 50 amp DC fuse). Ah, if only I had a schematic! Thanks again for your input. You may have forgotten much as you state, but it likely still amounts to more than I can ever hope to know.

 

[shrtrnd]

Keep looking for a schematic or directions on that reset value.
What I remember is the UPS's I worked on were wired so you couldn't just 'disable' the low voltage indicator.
It may be a pain, but it might have to be done. Engineered by the mfgr to protect their equipment.
I doubt your low voltage indicator/cut-off is defective. It just needs to be reset and I'm sorry I don't remember
enough to help you with that. Maybe somebody else here will see this post who is familiar with your model.
I feel your pain. What jogged my mind when I first saw your post, was my memory at my annoyance at getting
a UPS, replacing the batteries, and then having to reset the trip value on it.
At least you have a better idea of the problem now than you did before.

 

[Warren]

Shrtrnd, I am very grateful for your interest and your help. However, your concern for my "pain" is misplaced. Whether or not I am ultimately able to get this UPS working again, it is an enjoyable journey to try to restore this truly classic piece of engineering art to functionality. You are among the fine people whom I am meeting along the way.