Nikolas Britton wrote: > I'm currently planning renovations for the power mains supplying are > server room. One of the ideas I have is to float the entire room using > a isolation transformer.
Umph, that's normally only needed if you are seeing extreme line noise or have other serious problems with the building mains supply like a poor or faulty building ground. If you do have building grounding problems, then using an isolation transformer will probably help your equipment but the problem should still be fixed elsewhere. > The only problem to this solution, that I can > think of, is that all of the equipment that's attached to the other > end of the Ethernet cabling won't be isolated, the NIC cards do have > 1:1 transformer coupling for the wire pairs but... In the event of > power surges, spikes, brownouts, and/or nearby lighting strikes I feel > that It's conceivable for there to be a large voltage differential on > the wires that could damage the equipment on ether end of the wire. Actually, you don't even need a lightning strike-- one can see 50 to 100V swings in relative voltages between neutral and the fusebox ground or neutral and a water pipe just by having the building ground fail. [1] Adding an isolation transformer to the mix won't hurt, but it won't help that much, either. If you want room-wide surge suppression at the breaker panel, get a TVSS or a 10kVA or larger UPS. Consider something like the Leviton 54000 or 57000: http://www.weberelectricsupply.com/57000.html http://www.leviton.com/sections/prodinfo/newprod/npleadin.htm ...which are rated for 3-phase "wye" 120/208V or 277/408V @ 100 amps per phase, and run about two grand. The other choice would be to hunt down a PowerWare or maybe an APC Symmetra UPS, which will run 20-30K. Note that the APC Symmetra cheats and doesn't provide galvanic isolation during normal operation, whereas the PowerWare runs the inverter continuously which is a bit less efficient, but gives cleaner power. These sorts of units ought to have a "DC servo offset circuit", if I'm remembering the details and phrase right, which will compensate for a constant voltage differential between neutral and ground. -- -Chuck [1]: Three guesses as to how I know this? :-) _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
