Date: Thu, 17 Oct 2013 15:15:35 +0200 From: Ralf Mardorf <ralf.mardorf@alice-dsl.net> To: freebsd-questions@freebsd.org Subject: OT: UPS buying suggestion Message-ID: <1382015735.5852.100.camel@archlinux> In-Reply-To: <1382015420.5852.97.camel@archlinux> References: <CACo--msUpY-6r7MkuEvrPDpSVdFZyBotSA-eS7aLGMFDeq_vDQ@mail.gmail.com> <alpine.BSF.2.00.1310150911510.97788@wonkity.com> <CACo--mvUfcAy=0hyun21DZwSmdd=SmP7EeU-FVxJyiT_h4Rxkg@mail.gmail.com> <525F0138.1020304@fjl.co.uk> <20131017093820.6a8428de@X220.ovitrap.com> <alpine.BSF.2.00.1310162309200.14022@wonkity.com> <1381988697.5852.16.camel@archlinux> <20131017142910.61325830@X220.ovitrap.com> <1381992680.5852.45.camel@archlinux> <525FD4C8.1090600@fjl.co.uk> <1382015420.5852.97.camel@archlinux>
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On Thu, 2013-10-17 at 15:10 +0200, Ralf Mardorf wrote: > On Thu, 2013-10-17 at 13:15 +0100, Frank Leonhardt wrote: > > On 17/10/2013 07:51, Ralf Mardorf wrote: > > > On Thu, 2013-10-17 at 14:29 +0800, Erich Dollansky wrote: > > >> Industry is much worse. Their machines made early computers fail when > > >> the bigger machines started work. > > > I worked for an audio company. The audio workshops were rented rooms on > > > a farm, and the boss missed to check the values of the RCCB, which > > > nearly killed a friend. Bigger machines are a PITA ;). The RCCB had a > > > value that high, that it was dangerous to life for an audio workshop. A > > > big machine not only pollutes the mains, if you turn it on, it also will > > > "eat" the complete power and lots of it going in, doesn't come out. A > > > "normal" RCCB would turn off immediately. > > > > > > > > Most RCCB (aka ELCB, RCD) work (hereabouts anyway) work with > > counter-wound coils on the input and output of the supply such that he > > magnetic field is neutral if the current is the same. If it goes out of > > balance, it trips the switch. Normally 30mA difference is the rule. They > > don't have a value, as such. I heard that only 10mA is needed to > > interrupt your heart, but I've also heard 100mA. They're all potentially > > dangerous. It depends on the route taken by the current passes through > > your body Correct, I've got professional literature about this issue, but I'm to lazy top take a look now. Don't trust a RCCB! > - you'd have to try quite hard to get even 10mA in the wrong > > place, but I guess you could do it with rubber shoes and grasping the > > mains one your one hand and an earth spike with the other. I was taught > > to keep my left hand in my pocket when poking around stuff that might be > > live, and do it quite subconsciously. > > The one at home, in Germany called FI, has got a value of 0.03A for my > flat, the one at the farm had a value of 1A. > > "Handelsüblich sind Fehlerstromschutz-Schutzschalter in der Bauart A für > Bemessungsdifferenzströme von IΔN=10 mA, 30 mA, 100 mA, 300 mA, 500 mA > und 1 A." - > https://de.wikipedia.org/wiki/Fehlerstromschutzschalter#Kennwerte > > The keyword is "Bemessungsdifferenzströme", sorry I can't translate it. > 30mA is save, 1A will kill you, since it won't turn off the power if > your body should become the resistor. > > As mentioned before, a workshop in addition must use an isolating > transformer, by this galvanic isolation you can't get an electric shock > if you only have contact to the phase and ground. You need to have > contact to phase and neutral conductor to get a shock.
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