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  1. bwen08

    Relay Replacement on MetalClad Switchgear (Existing Doors vs New)

    We've never bought new doors, always used filler panels or patch panels. The last one we actually had a local waterjet company do all the cutouts on stainless steel sheets that were a tad smaller than the door dimensions, removed the door to bring into the shop, enlarged holes on the door to...
  2. bwen08

    Recommendations on power logger for medium voltage distribution circuits

    You might investigate the sensor from Aclara. I'm fuzzy on the specifications as its been awhile since they tried peddling them here, they have a website to use for data analysis and I believe they were cellular so you didn't have to worry about the communications...
  3. bwen08

    Substation Voltage Regulator

    Is there an R & X component on that regulator that doesn't match the other 2 phases? In the past we would set R/X values per phase and not have them matching across the board. Perhaps controls were changed out and someone didn't match the settings? We typically see 1-3k operations per year at...
  4. bwen08

    Rotary Phase Converter & Flicker

    I can't seem to find the magic site, paper or person to provide the info on rotary phase converters I'm after, and I bet someone here knows... For generalization, assume someone purchases a 30HP RPC to provide 3 phase power to a 15HP motor. What is the general inrush/flicker characteristics of...
  5. bwen08

    Fuse and Feeder Settings

    I've had a mix, some utilize maximum loading capabilities, others utilize lower settings based on historical loading and lack of available fault current on the feeder. Regardless, for primary fuses, check your breaker coordination taking accounting for preloading and multiple operations (fuse...
  6. bwen08

    140% Recloser Coil

    I don't know the context in the application, but 200% coils are the standard for Kyle reclosers. As the 140% pickup coils start at 280A, my assumption would be to provide increased sensitivity downline of the recloser. I could also envision the application of them if I were stuck utilizing a...
  7. bwen08

    wye to wye transformer grounding

    I don't adhere to NEC in my field so can't provide definite answers in regards to that. waross: I'm betting H0 and X0 are tied internally inside the tank possibly with a removable link (common unit). We've isolated H0 and X0 on some existing wye-wye units for an industrial customer, however...
  8. bwen08

    Transformer Phase Shift

    Instead of connecting the transformer H1/X1-A, H2/X2-B, H3/X3-C, physically change the buswork such that H1/X1-C, H2/X2-B, H3/X3-A. Sorry the ink has faded and required inversion.https://files.engineering.com/getfile.aspx?folder=d33f8e78-ef15-4bdf-b5e0-9a8795620029&file=Untitled.png
  9. bwen08

    How to test GFCI plug?

    Plug lamp into GFCI outlet, press the "TEST" button, watch light turn off. Press "RESET" button, watch light turn on?
  10. bwen08

    Circuit Breaker Contact Resistance Routine Test ...

    Check the breaker instruction manual, the manufacturers typically have an upper limit posted in the manual.
  11. bwen08

    Live line work vs fault current

    HamburgerHelper: The table lists fault currents (5k, 10k, 15k, etc) and maximum clearing times allowed to obtain a 4, 8, 12 cal system. Mbrooke: Our table has differences because the inputs into ArcPro differ for single-phase and three-phase arc flash. The arc gap ends up larger for three...
  12. bwen08

    Live line work vs fault current

    Mbrooke, the NESC table was once upon a time based on ArcPro's results, likely is still but I haven't compared 2012 to 2017. We utilize 2 custom variants of a similar formatted table, one for LG work, and one for 3 phase work. The question that has came up and we still can't answer however is...
  13. bwen08

    Need for a recloser in a distribution circuit

    We are a T Link utility for taps and inline fusing. Our crews will typically only take holds on feeders when they are in their normal configuration; when switching has caused major changes, we'll review the coordination before they take a hold to verify the reclosers are operating as expected...
  14. bwen08

    Need for a recloser in a distribution circuit

    To answer your original question, we install reclosers to feeders when they facilitate our needs. Reasons include: lack of sensitivity on the breaker, mainline splits, energized work requirements, or sectionalizing to reduce exposure. We serve an area of mostly rural but also have some larger...
  15. bwen08

    Low SF6 action

    We employ the same methodology as submonkey's comment on our SF6 breakers. Mbrooke: The factory control scheme provided two somewhat parallel SF6 lockout aux contacts in the trip circuit; one to block any remote trip from relays and a second that closes upon the SF6 lockout scenario and...
  16. bwen08

    Arc Gap and Working Distance for Higher Voltages

    For the arc gap, I used two equations, one for line-ground (VLG[kV] * mult * 0.1) and one for line-line arcs (VLL[kV] * mult * 0.1). The multiplier was pulled from the new OSHA standard for calculating the MAD distance based on the maximum transient overvoltage possible, mult=3 for 72.5kV and...
  17. bwen08

    CT sizing formulae

    Well since I just reviewed CT sizing recently I can point you to reference documents. I'm not sure where the differential equations you quote come from but the basic CT sizing equations and derivations are referenced in the following documents: "Selection of Current Transformers & Wire Sizing...
  18. bwen08

    Type T Fuse-Fuse Coordination --- 75% Rule

    With "T" link fuses, Kearney, Chance, and others all have their charts showing the maximum fault current that various fuse amperes coordinate up to. I understand the 75% rule attempts to take into account preloading, damaged fuses and link temperature. My searching so far has failed to lead me...
  19. bwen08

    Capacitor Banks on distribution poles?

    If all the VAR draw is at the end of the line, would you rather put the bank close to the load or all the way back at the substation and have more line loss? Also, if the feeder is changed to an alternative source, your would lose your power factor correction if you had a substation based cap bank.
  20. bwen08

    3 Phase vs Single Phase Distribution Voltage Regulators

    1. This is really going to depend on each situation, regulators are typically used here to bring the voltage back up and delay the cost of reconducting the line. 3. Get a quote for a three phase unit vs three single phase units. Single phase units have been regularly much cheaper in the...

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