Re (2): UPS with earth leakage device.
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From: no.top.post on 7 Jan 2010 03:27 In article <4b44e3c5$0$275$14726298(a)news.sunsite.dk>, ArameFarpado <a-farpado.spam(a)netcabo.pt> wrote: > Em Quarta 06 Janeiro 2010 17:23, no.top.post(a)gmail.com escreveu: > > But I can't understand since the UPS is designed to switch on AFTER > > the mains failure. > > wrong. OK, I don't want to influence original contributions, by giving my full present analysis. But the failure process takes a finite time. And I insist that the UPS can only acts AFTER the beginning of the mains 'failure process'. Can you contribute more than "wrong" ? --- philo wrote: > but if the problem was traced to the UPS > > chances are it was simply not grounded properly > > better get someone who knows what they are doing > to check the wiring etc No, AFAIK the earth-leakage -detector works by measuring the unbalance between the line and neutral current flow. Since the unbalance must be returning via the earth. So REMOVING THE EARTH to the UPS & computer circuit 'eliminates the problem'. But that's a bodge. One needs to fully understand the problem cause sequence. .. == TIA.
From: ArameFarpado on 7 Jan 2010 13:41 Em Quinta 07 Janeiro 2010 08:27, no.top.post(a)gmail.com escreveu: > In article <4b44e3c5$0$275$14726298(a)news.sunsite.dk>, ArameFarpado > <a-farpado.spam(a)netcabo.pt> wrote: > >> Em Quarta 06 Janeiro 2010 17:23, no.top.post(a)gmail.com escreveu: >> > But I can't understand since the UPS is designed to switch on AFTER >> > the mains failure. >> >> wrong. > > OK, I don't want to influence original contributions, by giving my > full present analysis. But the failure process takes a finite time. > And I insist that the UPS can only acts AFTER the beginning of the > mains 'failure process'. > > Can you contribute more than "wrong" ? You are confusing a UPS with a emergency electric generator; those are the ones that start working after the power goes off. A UPS needs to keep the power up without letting it go down even for a split second. The only switch a ups does when the power goes off is that it stops charging the batteries. The output of a UPS is allways given by the same circuits regardless if the power is on or off with power on: main power -> AC-DC converter -> DC-AC converter -> output -> charge batteries. with power off: batteries -> DC-AC converter -> output this is the only way that an ups can keep the output on without any breaks. so resuming: if the ups's output is given the wrong voltage, frequency, sinosoidal wave, etc... you have two choices: 1- repair the ups 2- replace the ups. regards
From: philo on 7 Jan 2010 19:52 > philo wrote: > >> but if the problem was traced to the UPS >> >> chances are it was simply not grounded properly >> >> better get someone who knows what they are doing >> to check the wiring etc > No, AFAIK the earth-leakage -detector works by measuring > the unbalance between the line and neutral current flow. > Since the unbalance must be returning via the earth. > So REMOVING THE EARTH to the UPS & computer circuit > 'eliminates the problem'. But that's a bodge. > One needs to fully understand the problem cause > sequence. > . > == TIA. > > OK figured it out A ground fault occurs when the "hot" lead of the mains shorts to the case of the equipment. So if there was a power failure there would be no "mains" lead to short to the cabinet... So the conclusion is reversed from what has happened It was a ground fault which *caused* the power interruption. The UPS simply was on because the "mains" breaker had tripped
From: ArameFarpado on 7 Jan 2010 20:22 Em Quinta 07 Janeiro 2010 08:27, no.top.post(a)gmail.com escreveu: > No, AFAIK the earth-leakage -detector works by measuring > the unbalance between the line and neutral current flow. > Since the unbalance must be returning via the earth. > So REMOVING THE EARTH to the UPS & computer circuit > 'eliminates the problem'. But that's a bodge. > One needs to fully understand the problem cause > sequence. > . > == TIA. if you have electrical questions, it's better to put them in sci.electronics.basics i can tell you that if you desconnect the earth, ther will be no more a neutral in the output, you will have two live lines with a voltage between them, and that could cause other issues.
From: Joe Pfeiffer on 7 Jan 2010 20:40
ArameFarpado <a-farpado.spam(a)netcabo.pt> writes: > Em Quinta 07 Janeiro 2010 08:27, no.top.post(a)gmail.com escreveu: > >> No, AFAIK the earth-leakage -detector works by measuring >> the unbalance between the line and neutral current flow. >> Since the unbalance must be returning via the earth. >> So REMOVING THE EARTH to the UPS & computer circuit >> 'eliminates the problem'. But that's a bodge. >> One needs to fully understand the problem cause >> sequence. >> . >> == TIA. > > if you have electrical questions, it's better to put them in > sci.electronics.basics > > > i can tell you that if you desconnect the earth, ther will be no more a > neutral in the output, you will have two live lines with a voltage between > them, and that could cause other issues. You can tell us anything you want, but if you tell us that you're wrong. Standard single-phase AC works with a hot line and a neutral line; neutral and ground are at the same potential. There should not be any current flowing through ground. See http://en.wikipedia.org/wiki/Ground_and_neutral -- As we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously. (Benjamin Franklin) |