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To: TGPTNDR who wrote (164389)	7/9/2005 11:34:41 PM
From: _Jules	Respond to of 275872

To: hmaly who wrote (164384) 7/9/2005 9:02:50 PM From: TGPTNDR of 164395 Harry, Re: which makes big devices,(it used to be rows of capacitors, I believe), now they are like magnets, which store electricity, in coils, just for such an event. He said they were used as back up in hospitals though, for what it is worth,however I assume something similar would be used there.> It sounds to me like those THINGS were used to take/provide high instantaneous loads. Like when you turn on a heavy air conditioner or big motor and the lights dim for 1/4 second or so. I'd GUESS that when a MRI machine(as an example) was powered up it would take substantial overcurrent before it got to steady state. Capacitors and BIG magnets are good for storing that kind of power. It's why Capacitor Start motors can generate high initial starting torque. I worked in a datacenter. Nowhere near as important for uninterupted power on the micro level as I would imagine for a fab. We used a room full of lead-acid cells, just like car batteries, but much bigger linked for primary failover.(The power busses and cables were truly impressive. Copper busses ~1/2 inch thick and ~6 inches wide.) Copper busses ~1/2 inch thick and ~6 inches wide. Those were the bus sizes on the USS. Coral Sea. It had 8 steam turbin generators. When a hydro dam went down that fed Calies France we anchored and ran some cables over and lit up the whole city, two generators were lit off. That was circa 1954-55. There is also whats called the Power Factor, the function allows power to start feeding with higher voltage or current. This of course using 3 phase. Jules

To: TGPTNDR who wrote (164389)	7/10/2005 6:17:06 AM
From: pgerassi	Respond to of 275872

Dear Tgp: I worked on a power supply for AT&T's Wells Street Long Distance Switching Center. It had Local (Toll) connections, Long Distance (Trunk) cables and Multiple Microwave Relay Antennas. All of these just had to run 24/7 with no power glitches, ever. Stable connections is the lifeblood of a communications carrier. The local lines are powered by 48V DC. These were powered by Lead Acid batteries with cells the size of washing machines. They were recharged continuously by MG (Motor Generator) sets (old, but reliable technology) and Inverters. By my calculations, they could supply all of the local lines being in use at the same time for over 36 hours without any recharge power. Another area had batteries for UPS to power all of the switching and transmitters. These were backed up by two 2MW gas turbines (about the size of a bread box) in a thick reinforced concrete bunker with lots of sound deadening so that employees could work without going deaf (those turbines are LOUD (180dB)) and protect the "delicate" equipment from the vibrations (more like built like an Army TANK). They had three primary feeds from the electric company (WEPCO), from the local substation, a direct line from the Menomonee Valley Cogeneration Power Plant (supplies steam and power to downtown Milwaukee) and another direct line to Lakeside Power Plant (now demolished). It was so reliable, they did not ever use those turbines under load until the company I worked for had them switch over non critical systems to verify that the connections could take the power. I couldn't believe they went 25 years (at that time) and never tested them under load (they had semiannual startup tests only). They worked with flying colors. Now that's reliability, late 70's style. Pete

To: TGPTNDR who wrote (164389)	7/10/2005 3:39:20 PM
From: hmaly	Read Replies (1) \| Respond to of 275872

Tgpndr Re...It sounds to me like those THINGS were used to take/provide high instantaneous loads. Yes, that is what they were for. They were big, and filled up a medium sized semi, and cost over a half a mil., and they provided power, I think, for less than a second. I am not sure, as the company downsized my brother out several yrs ago, and I forget, but I think it was less than a second. It was just enough time for the backup systems to kick in.