Generic UPS question - Page 1
Forum section: electronics / general

author: vtwin@cox.net
author_rank: Regular Contributor
timestamp: October 28, 2018, 02:58:43 pm
content: I have a fair amount of expensive equipment which runs on 240v in an equipment rack (about 13 amps total). A few months ago, a nearby lightening strike fried a cable modem, tv set, and the evolution controller on my generator. Fortunately, none of my expensive gear was damaged.I'm now paranoid, and it got me thinking... Maybe I should put a 240v UPS in the rack to act as a surge protector/line conditioner (right now I just have a PDU connected directly to a L6-30R, and all my gear connected to the PDU). I do not really need the UPS feature, so buying a used unit w/ crappy batteries is okay by me.I've been looking around for used 240v 6kVa UPSes and I cannot find anything which is in my price range.I can, though, find a good number of used Eaton 9135G 6kVa UPSes nearby (no shipping!) which take, according to the specs, 208-230vac input and have selectable 240vac output.So, my question is:1. Since I only have 240v line power, would there be anything "bad" about using a 240->230 buck/boost transformer to take my 240 line power and convert it into 230v to feed into a Eaton 9135G, which I can then feed out @ 240v to my gear. I have no experience with buck/boost transformers but a 240 to 230 Larson MT-BBT-240V-229V-30.57A step-down transformer is about $180, which still makes the project reasonably priced.or2. should I just save more money and look for a "reasonably" priced UPS which takes 240v input and gives 240v output (if so, any recommendations?)thanks,

author: GeoffreyF
author_rank: Regular Contributor
timestamp: October 28, 2018, 04:21:03 pm
content: I would find out if your building is properly grounded and has suitable lighting rods.Ground stakes do not last forever and especially with some types of soil. What I would do, and even recommend where a ground stake is of unknown age, is simply drive a new one next to the old and strap them together with suitable cable and connectors. Consider connecting cold water pipes as well. I would also assure that the lighting rod has a separate ground not close to the electrical system one.If you have antennas, make sure those have suitable suitable lighting arresters, also with their own ground stake.Purchase a ground stake, connectors and cable, made for that purpose from your local electrical supply. They should be about 8 feet long, driven almost entirely into the ground.A UPS is not by itself protective. It may have components that are though.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 28, 2018, 06:36:31 pm
content: Most UPSes are standby, that means relays flip over to inverter when power goes out. Won't be able to react fast enough for a surge, though it might still help as the MOVs or whatever surge protection is built in will react first then by then the relays will have switched over too isolating from the surge.One thing I want to do eventually is do like the telcos. Have AC come in to AC-DC converters (we call them rectifiers) then that float charges a battery bank, then everything runs off that battery bank. It would create isolation to some extent, where the rectifiers would probably take the brunt of the surge and the batteries and stuff on the DC side would probably be ok. Though I guess you still want some beefy surge protection as if the lightening arcs through everything and hits the batteries you'll have a pretty massive explosion on your hands. I'm not sure what the telcos do tbh to protect from that. As far as I see the AC comes straight into the rectifiers. The switch gear room might have some form of surge protection I imagine that would quickly cut power out. You can only shunt a surge to ground for so long before something blows up, so you still want some kind of mechanical isolation to react at the same time.

author: ajb
author_rank: Super Contributor
timestamp: October 29, 2018, 04:41:43 am
content: You're overthinking the 230 vs 240VAC thing. In practice 220, 230, and 240VAC are all the same thing due to the margins of error involved in line power. Anyway the specs for the UPS you indicated that I'm seeing say 200-250VAC. So you're good anyway.No UPS is going to be much of a guarantee against a direct lightning strike, but it certainly won't hurt, and may protect against less severs faults. Just beware of other possible paths for lightning energy, like cable TV or telecom lines, that may bypass any protection on the AC line.

author: vtwin@cox.net
author_rank: Regular Contributor
timestamp: October 29, 2018, 12:03:20 pm
content: Quote from: ajb on October 29, 2018, 04:41:43 amI think you're looking at the output power, which is configurable. Input line voltage is 208-230 nominal. An eBay seller with one is about 10 miles from my house, so I've been up to take a look at one and test it prior to buying. Connecting to 240v power yields an "environment fault, load unprotected" error, presumably because input power is "out of spec" at 240v. The seller suggested a buck/boost transformer to drop the input voltage to <230v which would bring it into spec and eliminate the error. Output power could still be 240v, configurable from the panel. Although this seems reasonable, I have no experience with BB transformers, so didn't know if this was reasonable or not.[QuoteNo, I'm not looking for direct lightening protection. My antenna systems are all properly grounded. The nearby strike which took out my gear apparently came in on the CATV line -- literally burned a hole though one of the ICs on the cable modem's motherboard. From there, it traveled through the network cabling and took out one of my smart TVs, as well as two Raspberry Pis (one running Pi-Star, another running GenMon connected to my Generac generator.). From the Pi in the generator, it traveled through the RS232 port and fried the modbus port on the generac evolution controller.The only PITA has been the evolution controller - I'm still waiting on Generac to send my service dealer a replacement. Everything else was easily repairable with a visit to Best Buy (cable modem), Amazon (PI motherboards), and eBay (TV controller board)I know there are ethernet line surge suppressors, but I have no real information on their effectiveness.I am investigating installation of a level 1 and 2 SPD on my meter socket and branch panel as well.

author: sokoloff
author_rank: Super Contributor
timestamp: October 29, 2018, 12:41:51 pm
content: Quote from: vtwin@cox.net on October 29, 2018, 12:03:20 pmIt's hard to beat optical fiber for electrical isolation. I use fiber to connect my main house to the garage and it's only 30 feet away. Gigabit fiber converters are cheap, reliable, and readily available. I'd trust that over a magnetic solution any day.

author: ajb
author_rank: Super Contributor
timestamp: October 29, 2018, 08:15:48 pm
content: Quote from: vtwin@cox.net on October 29, 2018, 12:03:20 pmEverything I see says the input is least 200-250V. Likehere. Actually the specs are all over the place, the manual says 156-280V.Anyway it would be silly to make separate 208V and 240V models of something like a UPS, the ranges are so close it's way less work to make one ~200-250V product than to maintain two separate SKUs. There might be a configurable overvoltage trip that should be changed depending on the nominal supply it's hooked up to, or if it's something fairly old maybe there's a tap change required. Interestingly the manual shows the "Environment Fault" message in one of the front panel graphics, but makes no other mention of it, so that's weird.

author: vtwin@cox.net
author_rank: Regular Contributor
timestamp: October 30, 2018, 12:38:38 am
content: Quote from: ajb on October 29, 2018, 08:15:48 pmAgreed, it is very confusing.... How the brochure has it listed:Seems to imply there are three "models", the 208, 230, and finally selectable.There's no option on the panel of the unit I looked at to select an input voltage range, so I think I'll drop an email to Eaton and ask for clarification. Their manuals suck.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2018, 12:56:39 am
content: One cheap and effective way to surge protect a cable TV line is to bond the shield to mains ground right at the modem. If that causes EMI problems, put some ferrites on the coax ahead of the ground point. (Or put ferrites on the ground wire, but that might reduce its effectiveness.)

author: edpalmer42
author_rank: Super Contributor
timestamp: October 30, 2018, 03:36:57 am
content: Quote from: vtwin@cox.net on October 30, 2018, 12:38:38 amI'm not familiar with this unit, but there's probably only one 6KVA model. You tell it what the nominal input voltage is and it will alarm if the voltage drifts too far from nominal. This also means that the batteries will only be used when the input voltage is outside the nominal range. This allows you to configure the unit for your particular situation. The 156 - 280 VAC is the absolute min and max input voltages that the unit will allow. Beyond that it will probably disconnect the input and go to full battery operation. I've seen this feature on other UPSs. The manual should explain it all.Since the topology is listed as 'Double Conversion', that means that it always runs on the batteries. Cheaper units run off AC normally and switch to the batteries when the power fails. Normally, double conversion is a good thing, but I don't know if a 6KVA double conversion unit would be happy running with bad batteries. It could be stuck in permanent alarm, or it might not work at all.