Uninterruptible power supplies

I did: something like 180 V RMS into a high-resistance load which dropped to about 30 V with even a nominal load - I managed to find a 25 W cooker bulb and lashed up a connection to it and even that caused the voltage to drop immediately. I *think* (though it was a while ago and I may have forgotten) the voltage returned to 180 when the load was removed (leaving just the voltmeter) so it wasn't just that the battery was flattened. That's why I wonder whether the inverter was shagged-out.

But I should have persisted with it... Ah well.

They had all manner of surplus electronic kit from various places: TVs, tape recorders, radios, record players. I even saw a broadcast-standard open-reel video recorder of some strange format. Great big appliances with big knobs and valves or else circuit boards of discrete transistors - not an IC in sight! I think the manual for my scope was dated 1968 so the technology dated from then. I bet nowadays you can get a little oscilloscope adaptor with USB output for recording and display on a PC. The shop was a real Aladdin's cave of stuff - shelves full of things that most people probably wouldn't even have been able to identify. It was a shop within a terrace of houses - a real back-street "you'd never know it was there" place. That was in the mid-80s; I doubt whether it's still there now.

Reply to
NY
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No, there are online ones that adjust the output voltage to keep it in spec. The APC SmartUPS series do that (I have three).

They electronically adjust the taps on a transformer (probably an autotransformer, I've never looked) to trim over-high voltages and boost low ones. If it goes too out of spec, then it'll switch to battery to keep it going.

This is one of the reasons I use the UPSs - round here we seem to get a lot of voltage fluctuations.

Reply to
Bob Eager

Sorry, my first sentence should have said 'offline' of course. Runs with the mains unless it goes way out of spec or fails, then uses battery.

Reply to
Bob Eager

Stewart of Reading? If so, yes they are still around but have moved out of town.

Reply to
charles

I have an APC Smart UPS 1500 (pretty old). I got it second hand with no batteries, then bought new batteries for it. It has LEDs to indicate what it's doing, and very often chops 10 or 20V off the mains as I have a very high mains voltage (the substation is over the road from me, and the power company won't do anything about it - they just quote some absurdly high legal allowances for tolerance - I've measured up to 267V). Sometimes an LED indicates "unacceptable mains" - not sure if that's outwith the voltage range it can buck or boost with the transformer, or whether it's fluctuating too much, but it then gives an output from the inverter while charging the battery from the dodgy mains at the same time.

Protecting expensive equipment and/or files is far more important than a little power wastage, which will be given off as heat anyway so if the room needs heated you've lost nothing.

Checking mine with a scope, it's a very clean sine wave of the right frequency, including under load.

Reply to
Commander Kinsey

What on earth is a "bird strike"? It would need to be a damn big bird to damage a power line. The only excuse I used to get when living in a remote area was "bull knocked over a pole".

Surely it does that itself?! Mine even has LEDs to indicate the battery charge level and a warning if it considers the battery nearing end of life.

Using mine with a battery like that produces a red LED with a battery crossed out symbol, meaning "replace battery".

Reply to
Commander Kinsey

They must be very small units. I have one which powers the lights for the whole house, a desktop computer, 5 monitors, a stereo, a router, and an inkjet printer. It's rated at 960W, 1500VA.

Reply to
Commander Kinsey

My car battery can go flat in one night if I don't charge it. I never found the problem. Even with every single fuse out it still does it. I've logged up to 5 amps being drawn from the battery using a logging multimeter. Yes it's a French car.

Reply to
Commander Kinsey

So you're dishonest about being dishonest and think abuse is the way to go. Mmkay. Or just well confused perhaps.

Reply to
tabbypurr

Were you the only one to bother reading it?

Reply to
tabbypurr

Sulphated. Lead acids left flat for 18 months have no chance really.

NT

Reply to
tabbypurr

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