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posted by takyon on Tuesday August 09 2016, @03:34PM   Printer-friendly
from the you're-grounded dept.

Cringley speculates like hell:

Delta Airlines last night suffered a major power outage at its data center in Atlanta that led to a systemwide shutdown of its computer network, stranding airliners and canceling flights all over the world. You already know that. What you may not know, however, is the likely role in the crisis of IT outsourcing and offshoring.

Do any Soylentils have inside/better information?


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  • (Score: 0) by Anonymous Coward on Tuesday August 09 2016, @04:44PM

    by Anonymous Coward on Tuesday August 09 2016, @04:44PM (#385838)

    Most if not all new buildings are build with ground fault interrupt on the main.

    1) high raise in concord failed twice in a month. First was a rebuild and saw through a wall cut the ground and hot together. Tripped the whole building. Second was a electrician checking to see if the line was hot by comparing to ground.

    2) major Corp data center in Florida. Again electrician was checking the line was hot before working on it. Tool out 5 main frames plus 20 more minis. With the open indexes. Took a while to come on line again.

  • (Score: 0) by Anonymous Coward on Tuesday August 09 2016, @05:35PM

    by Anonymous Coward on Tuesday August 09 2016, @05:35PM (#385867)

    Just how sensitive is a ground fault interrupter? Hard to believe that a decent voltmeter (with high input impedance, >10meg ohms) would draw enough current to cause a ground fault?? Or do electricians normally use a low impedance VOM??

    • (Score: 2) by Scruffy Beard 2 on Tuesday August 09 2016, @05:56PM

      by Scruffy Beard 2 (6030) on Tuesday August 09 2016, @05:56PM (#385876)

      According to this page (PDF) [nema.org] the standard trip current is about 6mA.

      120V/6mA=20kOhms.

      But a whole-building supply may be a 600V, raising that to 100kOhms (within an order of magnitude of 1MOhm).

      Now why a whole-building should trip on 6mA, I don't know.

    • (Score: 0) by Anonymous Coward on Tuesday August 09 2016, @08:34PM

      by Anonymous Coward on Tuesday August 09 2016, @08:34PM (#385942)

      Those sorts of devices can indicate phantom voltages.
      For a Go/No-Go test, an electrician will tend to use a device that pulls a bit of current. [google.com]

      -- OriginalOwner_ [soylentnews.org]

    • (Score: 1) by jrmcferren on Tuesday August 09 2016, @10:42PM

      by jrmcferren (5500) on Tuesday August 09 2016, @10:42PM (#386005) Homepage

      The ground fault relay is probably factory set to 50 amps or so. These aren't your standard GFCI circuits, these are designed to trip to prevent a nasty arcing fault from occurring. When installed correctly the relay is set to take in account the tripping curve of the largest downstream breaker (both time and current) with the idea that a fault in a branch circuit will trip ONLY it's circuit breaker and the ground fault relay only trips IF there is a fault in the switchgear itself. In this case there was likely either the incorrect product installed (a low threshold device that operates more like a GFCI) or there was an accident and the relay was not coordinated with the downstream breakers. Remember, a ground fault should only ever activate one overcurrent (fuse or breaker) device if everything is coordinated correctly.

  • (Score: 1, Interesting) by Anonymous Coward on Tuesday August 09 2016, @09:44PM

    by Anonymous Coward on Tuesday August 09 2016, @09:44PM (#385984)

    Transfer switch the thing connects the internal supply (UPS generally) to either the grid or generator. That is what when out, hence "power problem".

    Work in Memphis, where we had that problem one day. The transfer switch was located outside of the build on a 6ft "power pole". Conduit ran to grid transformer, generator, and into the building. Was located there so it could be tripped manually by security guards (just in case), with getting access to equipment.

    Karma and lightning is bitch. The lightning bolt hit the transfer switch frying it. Generator also cooked. UPS, too. Grid transformer was good, but no way to power the reconnect quickly. The main frames internal dual "UPS" gave it 5 minutes to shutdown before those main primary batteries went dead. 2x 30A 3-phase, to dual 300 pound, top of cabinet mounted. Actually comes with an "engine puller" device to get them up there and take it back down. The main cabinet had dual 500VDC buses (one from each UPS) that each card/planer connected to., each with dual voltage power regulators. Think Googles 48V cabinets were cool.

    Hell on main frame, it had dual battery packs (looks like 6 AA) and memory on each disk controller card, just in case to handle failure of the actual card or one memory module. You could pull the memory & battery (keeping the memory "fresh") and plug into another card and continue, keeping the raid-5 fully in sync.