RE: MAE-East still no generator
In some telco facilities that do have AC generator backup, there are a few seconds of down time while the generator kicks in. In these spaces, AC equipment will in all likelihood re-boot, while DC equipment stays up through the transition. -- Jim
In some telco facilities that do have AC generator backup, there are a few seconds of down time while the generator kicks in. In these spaces, AC equipment will in all likelihood re-boot, while DC equipment stays up through the transition.
That's why the PAIX is wired thusly: +--------+ Utility----->|Transfer|--+->Rectifier---->Battery---->Cage DC Generator--->| Switch | \ +--------+ \ +======+======+ UPS UPS UPS | | | Transfer Switches \ \ Cage AC The batteries are sort of the capacitor in a huge DC power supply. The triple AC UPS is so that the electricians can do maintainance on one of the UPSes while still leaving two others online. Stephen was talking about dual rectifiers and a DC transfer switch but I havn't been in that room for a while so I don't know if that happened. It costs a lot of money -- almost as much as connectorizing the cross connects -- but the goal is 100% uptime on both the AC and DC.
That's why the PAIX is wired thusly:
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The batteries are sort of the capacitor in a huge DC power supply. The triple AC UPS is so that the electricians can do maintainance on one of the UPSes while still leaving two others online.
Stephen was talking about dual rectifiers and a DC transfer switch but I havn't been in that room for a while so I don't know if that happened.
Last I counted there were five rectifiers. The single-line drawing is back at my office, though, and I don't recall how they're wired.
It costs a lot of money -- almost as much as connectorizing the cross connects -- but the goal is 100% uptime on both the AC and DC.
Yup. The air conditioning is wired into the city and generator power so that it will run during a power failure, but not drain the UPS' batteries. The UPS (and DC, of course) batteries charge off the generator - since it takes longer to charge than it took to drain, sometimes you have to run the generator longer after city power comes back, to make sure that the batteries have charged enough should the power fail again (and perhaps again, and again after that) right after you've switched back to city power. It's a worst-case scenario, but if your city power toggles a couple times in a day, you could lose your entire battery charge in increments, and not have enough to carry you until your generator kicks in. Just out of curiosity, does anyone have any personal experience with losing utility-provided power more than, say, three times in a day? Stephen - ----- Stephen Stuart stuart@pa.dec.com Network Systems Laboratory Digital Equipment Corporation
Just out of curiosity, does anyone have any personal experience with losing utility-provided power more than, say, three times in a day?
Yes. Thats why we have two util feeds to an ATS, then to a generator w/ and ATS and two UPS's. There are two substations in our area, an east and a west. On any feed failure we switch to the other feed. We start the genset if the UPS comes on and run it for 10 min, regardless. Our experience has been that if one feed goes down the other remains but has an occasional blip. We have see the ATS go back & forth a up two *four* times during a 24 hour period. The genset had about an hour of runtime for that day. +------+ +---+ |Genset-----|CTL| +------+ +-|-+ | | East Substation ---- +---+ +-|-+ +-----+ -- DCREC --- DC FRAME |ATS| ------- |ATS| ---- |UPSx2| || West Substation ---- +---+ +---+ +-----+ --- AC ------ AC GRID We a just a little ISP, not a major interconnect point. But, to coin a marketing phrase, "all reliabilty starts with the power."
participants (4)
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dougd＠airmail.net -
Jim Browning -
Paul A Vixie -
Stephen Stuart