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Recent content by busbar

  1. busbar

    Grounded to a water pipe picture û requesting comments

    I would scrap the entire installation and install a single, properly sized, listed ground clamp that has not been field-fabricated or field-modified like the two pictured. The top clamp has “stacked” washers/hex nuts that do not appear to be part of the original assembly, and the lower mess...
  2. busbar

    MCCB single pole interrupting rating

    ASIDE: The (old) Westinghouse [EHD] and GE [TED] MCCB "frame books" listed single-pole interrupting ratings as 8660 amperes.
  3. busbar

    Potential Transformer Primary Fuse Basis for Sizing

    No one has cited this one yet… From IEEE C57.13 7.7 Short-circuit capability Voltage transformers shall be capable of withstanding for 1 s the mechanical and thermal stresses resulting from a short circuit on the secondary terminals with full voltage maintained on the primary terminals...
  4. busbar

    Is anyone aware of the origin of the term Pallet relay? We use multip

    Are you sure you don’t mean ‘pilot relay’? See http://www.gedigitalenergy.com/multilin/notes/artsci/art15.pdf
  5. busbar

    Distribution Transformers in same Area blowing same phase

    Do a Google search on transformer ferroresonance. At least it may be something to rule out. IEEE std C57.105 §8 has some basic information on transformer susceptibility to ferroresonance.
  6. busbar

    Step down transformer for Asia

    You might consider something like a “Group-U” [440Δ - 220Y/127V 3ø, 50Hz] transformer listed at www.acmepowerdist.com/energy-efficient-transformers-three-phase.htm
  7. busbar

    Earthing

    Although somewhat dated, you may want to look over http://www.everyspec.com/NIST/NIST+-+FIPS/FIPS_PUB_94_33007/
  8. busbar

    triplen currents?

    Steve, don’t even-order harmonics indicate DC offset in the waveform? That would seem to present its own set of problems.
  9. busbar

    triplen currents?

    Check out back issues of EC&M magazine. { www.ecmweb.com } There have been numerous articles on triplen and other power-system harmonics. One caveat—the online material is without charts, photos or illustrations. You have to purchase the articles to get those.
  10. busbar

    GFI on main service

    Another provider is www.boltswitch.com
  11. busbar

    Phosphor Bronze fastners for transformer terminals

    www.keybellevilles.com is one manufacturer, but beware of their healthy minimum quantities and setup fees. www.sandc.com has, in times past, filled smaller orders for me.
  12. busbar

    Ferroresonnance in earthed singe phase supply.

    A de facto document is ANSI standard IEEE C57.105-1978 IEEE Guide for Application of Transformer Connections in Three-Phase Distribution Systems §7, that be of some help.
  13. busbar

    Switchgear and Transformer Clearances/Location

    ISTR that, in North America, typical listed drytypes have clearance requirements stated either on the label or packed with the transformer.
  14. busbar

    Open Delta - Open Wye Fault Question

    An aside—from practical experience, voltage-mode imbalance [ANSI device 47] protection should only be applied to inhibit 3-phase motor starting—where current-mode relays [ANSI device 46] are needed to reliably interrupt motor running.
  15. busbar

    Need help sourcing terminal

    Another supplier is JST corporaton at http://www.jst.com
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