I have a 3.0kVa UPS (uninterruptible power supply) for computers. The RCD has been tripping. I have a couple of extra boxes to extend run time, each with 12 batteries. The UPS itself has six 9AH batteries.
I finally found a leaking battery was the problem. It was the last thing I expected. So if you are at a loss for something along these lines check the bottom of all batteries.
In series so could have open circuit, but would that trip RCD??? One for the experts.
Don't know how a DC circuit is directly related to RCD fault,,, I thought low power in DC circuit (or open circuit) would just shut down the UPS itself,,,, but hopefully someone will know.
Very interesting,,, renewed my faith in the forum,,, finally something to read,,, better say lol here. lol
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Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
There was 66 volts through the case. 66 volts was strange as the voltage should be around 80 volts with 6 batteries. The RCD tripped & the UPS went into battery mode so the UPS was suppling 240 volts. The extended battery boxes are earthed back through the actual UPS.
I also have a proper surge protector between the wall & the UPS.
But it has made me think I really need to get an RCD for everything that plugs into the UPS as the RCD for the building in not going to help for anything running off the UPS.
This would be the same situation if you are running 240 off your axillary batteries in a caravan. You need an RCD on the inverter then plug in your kettle into it!
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There was 66 volts through the case. 66 volts was strange as the voltage should be around 80 volts with 6 batteries. The RCD tripped & the UPS went into battery mode so the UPS was suppling 240 volts. The extended battery boxes are earthed back through the actual UPS.
I also have a proper surge protector between the wall & the UPS.
But it has made me think I really need to get an RCD for everything that plugs into the UPS as the RCD for the building in not going to help for anything running off the UPS.
This would be the same situation if you are running 240 off your axillary batteries in a caravan. You need an RCD on the inverter then plug in your kettle into it!
Hmmm
It is hard to say what the real voltage would be on the case as sensed by a human. Meters do not read the same in all situations. You only need 60ma to trip and possibly 60V in bad situations to kill.
Back some years I was in a lab that had an old still. NO NO not that kind of still but for distilled water. When I turned it on after not being used for a while, it always tripped the RCD once or twice. Then it was OK till turned off. So I had to do it early first thing Monday so it did not annoy others and trip off their computers and things running. I guess the element had a miniscule leakage and the first current dried it out as it tripped. Worked OK for years like that and it was in a glass chamber. It eventually was broken and replaced by a de-ioniser which looked very unimpressive compared to the glass still .
I have said several times the 240 V from an inverter or UPS kills just the same as the 240 at home and has much less safety built in to the basic installation. There have been discussions about the saftey trips available. RVDs may better suit. https://www.rvdsafe.com.au/
Yes I fitted RVD about 4 years ago, for those reasons when on inverter and genny and using more than 1 class 1 appliance (3 pin plugs). Was first one sparky ever installed, and he rang manufacturer before installing. Occasionally trips in van parks on first plug in. Have found a couple of suspect 240v outlets but park owners couldn't have cared less.
__________________
Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
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