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  1. avogel

    Battery Room requirements

    NFPA 70E requires ventilation systems, forced or natural, to prevent buildup of explosive mixtures in battery rooms. A determination must be made for each battery area as to whether sufficient ventilation is being provided. Reference your battery manufacturer for the hydrogren gas evolved, it...
  2. avogel

    hadron collider 18kV failure

    I remember there was an IEEE Spectrum article on it awhile back, they seemed to be connected to both the French and Switz grids and ran somewhere inbetween 220 and 300 MW. but, this failure didn't have anything to do with where their power comes from, from the pictures it looked like a...
  3. avogel

    hadron collider 18kV failure

    So I wonder if these nuclear physicists are a bit behind on cable testing practices. A comment like power failures are not that rare for a new $10 Billion accelerator seems odd to me!
  4. avogel

    Device Net Communications Failure

    It's possible the buffer is causing your issue, there isn't enough information from you to really make a decent conclusion, but at the get go, verify they haven't violated any devicenet wiring rules, ie: trunk length and terminating resistors on both ends for the Tx and Rx. You may need...
  5. avogel

    Bad Power Factor Measurement

    What kind of load is it connected to? could it be something that could be distorting the waveform? digital meters can be flukey like that.
  6. avogel

    Electrical/Comm. cable separation?

    yeah um ok, semantics. in any case. i still would check out article 800, because you will find its not allowed, even if your cable is 300v rated.
  7. avogel

    Electrical/Comm. cable separation?

    Maybe you can better define what electrical and comm are in this applicaton, but strictly speaking, if you are mixing conductors with differenet insulation ratings (ie: 300V and 600V) it's not permittted off the bat. Also, if you dig into Article 800, it is also not permitted to mix...
  8. avogel

    Running Telephone Cable in medium voltage cable tray

    Actually, it appears that none of the armored telephone cables are even listed for use in Cable Tray. Looks like there is little doubt I will have to install it in conduit. I agree with using fiber too but that's another issue I asked about, but we still are required to run twisted pairs...
  9. avogel

    Running Telephone Cable in medium voltage cable tray

    I am in the US, so hoping to get some thoughts from an NEC compliance perspective. We need to run a telephone cable and the only route is a 20kV cable tray with Type MC cable. 392.6 allows you to run Class 2 circuits in the same cable tray if the cables >600V are Type MC, however it appears...
  10. avogel

    references on root cause analysis

    TapRoot: Changing the Way the World Solves Problems - by Mark Paradies & Linda Unger
  11. avogel

    Relay coordination

    Hire a licensed PE consultant who knows what they are doing!
  12. avogel

    GE JBC Relay - Need Info

    Thanks for the link, however I already have looked through those and couldn't find what I'm looking for. "Not sure how you ordered a replacement if you are not sure what you have..." I am sure it is what we want since we use that model on the rest of our similar feeders for 67 protection...
  13. avogel

    GE JBC Relay - Need Info

    I'm looking for the manual on an early type JBC Relay: Model 208A8458 G-2 The publication on the nameplate is 'GEK-36836', which is not on GE's website, and the folks at GE say doesn't exist, but that doesn't make sense because it's clearly engraved on the relay. I am specifically looking for...
  14. avogel

    High-frequency electricity shock risk

    That is not true at all, and you shouldn't rely on anecdotal information. When a load has capacitance or inductance, the impedance will change with respect to frequency.
  15. avogel

    Rectifier configuration Harmonics

    Not to hijack your thread, but I was looking at some 6 pulse rectifiers today. 2 of them were connected in parallel with the other, but the primaries were connected as shown in my attachment. This is supposedly a 12 pulse equivelant. I do not see how you get a 30 degree shift from T1 to T2. Can...
  16. avogel

    Determination of 3-Phase Power Distribution Transformers

    To check your apparent power result, you can calculate the FLA to see if it matches nameplate on the motor : I = 247000 / (V * .88 * 1.73) Your answer should be close. But I must say there are special considerations when sizing a transformer and motor feed. I would not recommend someone not...
  17. avogel

    Automatic Power Factor Correction Faults

    This is an original unit circa 1980s. The load has not changed in this time period. So far we have experienced 4 disturbances, each which has popped up after a few months of running great. The unit is connected to a 4160V circuit with several 6-pulse DC rectifiers. There are 5 steps, each bank...
  18. avogel

    Power Recorder Reading - 5 Elevator Bank

    Your #1 observation doesn't suprise me, though 100 percent maybe higher than normal. When you use a drive you have to be aware of the current harmonic distortion produced (especially 5th and 7th). That's why in some VFD applications people use a 5% impedance line reactor to mitigate this. Though...

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