Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. SJBatTCE

    DGA limits for silicone insulating fluid in transformers - C57.146

    I'm looking for limits of dissolved gases in silicone transformer insulating fluid. Does IEEE Std. C57.146-2005 cover these?
  2. SJBatTCE

    Incident Energy with CL Fuse Equations

    davidbeach, I agree concerning the realistic accuracy of system models, both utility and industrial. Sometimes I feel I am doing surgery in the dark with the arc-flash analysis. But at least the hazard is being addressed. I think I've gotten a fairly good sampling of the community's feelings...
  3. SJBatTCE

    Incident Energy with CL Fuse Equations

    From experience as a former utility engineer, the utility provides this information as a service, not as design information. NFPA 70E recommends updating a facility's arc-flash study every five years (if I'm wrong, correct me) ,if no major changes have occurred on the facility system, in order...
  4. SJBatTCE

    Incident Energy with CL Fuse Equations

    I actually haven't had too difficult of a time getting realistic fault currents from utilities. I've done arc-flash analysis for companies across the U.S. and had pretty good cooperating with most utilities, once they understood why I needed an accurate value. Usually you just need to talk to...
  5. SJBatTCE

    Incident Energy with CL Fuse Equations

    Thanks for the responses. dpc, what is your reason for not using the equations? PHovnanian precisely states my concern with using the equations.
  6. SJBatTCE

    Incident Energy with CL Fuse Equations

    Post to link to KRP-C TCC.http://files.engineering.com/getfile.aspx?folder=b1950191-2abc-47d4-8ef1-b6967ff15689&file=KRP-C_Arcing.pdf
  7. SJBatTCE

    Incident Energy with CL Fuse Equations

    I don't care about equipment withstand here. I'm conducting an arc-flash hazard analysis. I've already determined in another part of this study that the equipment is suitable for an infinite source bolted fault. Where did I mention equipment fault withstand? In IEEE 1584 Section 5.2, an...
  8. SJBatTCE

    Incident Energy with CL Fuse Equations

    Does anyone else have a problem with the IEEE 1584 incident energy equations for current limiting fuses? Incident energy is based on the arcing fault current, not the bolted fault current. Arcing fault current is determined from the bolted fault calculation but takes several other variables...
  9. SJBatTCE

    SCCR marking for dual voltage panel

    Good point, jraef! I hadn't thought about that. Assuming an infinite primary bus, a 50kVA dry-type with approx. 5.0%Z, only about 1200A can be delivered to a bolted 3-phase fault. Still, I have no control over the source of the 480V; customer may decide to feed from a separate 480V utility...
  10. SJBatTCE

    SCCR marking for dual voltage panel

    Yes, there is a fused switch before the conductors exit the panel to the transformer.
  11. SJBatTCE

    SCCR marking for dual voltage panel

    I've been asked to evaluate a panel for SCCR labeling. The panel is fed from a 575V source. The 575V source feeds some 600V equipment, leaves the panel to an external 50kVA 575/480V transformer, then the 480V circuit comes back into the same panel and feeds 480V equipment. So, how do I label...
  12. SJBatTCE

    50N vs 50G Currents

    I actually had this problem in a motor protection application. The 50G would pick up during starting, but there would be no 50N (core balance CT) current. The DC component of the phases would not balance in the calculation, but no return current was present, I assume because the generator...
  13. SJBatTCE

    LTC and transformer ratings

    What is the effect on a transformer's capacity compared to nameplate if the transformer secondary LTC is lowered or raised from neutral?
  14. SJBatTCE

    Arc-flash on Grounded-B system

    That's what I'm inclined to do here. My arc-flash numbers will be quite conservative as there will be only two phases contributing to the fault, correct?
  15. SJBatTCE

    Arc-flash on Grounded-B system

    Anyone have suggestions for conducting an arc-flash study on a 480V, three-wire, grounded-b system? Is this possible? If so, should it be treated as an ungrounded-delta? Not sure where to start with this one... TIA!
  16. SJBatTCE

    Your take on Arc Flash labeling

    Taking into account the plasma stuff, I see your point. thanks for taking the time to help me reconcile my own conflicting opinions about this.
  17. SJBatTCE

    Your take on Arc Flash labeling

    What would be reasonable to reduce the hazard for this panel directly off of the transformer secondary? 2000A fused disconnects are rather expensive and you've transferred the HRC to another device.
  18. SJBatTCE

    Your take on Arc Flash labeling

    I can agree with that logic. But I also think that with panels that provide barriers over the main breaker and incoming feed that require additional disassembly beyond what is required to access the buswork should substantially reduce the risk of accidental contact with the higher available...
  19. SJBatTCE

    Your take on Arc Flash labeling

    When you have a panel feed directly from an unprotected source (i.e., large transformer secondary) you will generally have a high arc-flash hazard at the incoming lugs of the panel. On an installation such as an I-line (or similar construction), will the selection of the main breaker settings...
  20. SJBatTCE

    ITE CR Frame Switchgear?

    jraef, I've managed to make contact with another Siemens person in the meantime. I haven't had much luck with Shawmut on obsolete stuff; if it isn't current they won't provide info on it. They wouldn't provide info in the past on ATS-DE fuses because they were obsolete and didn't have curves...

Part and Inventory Search

Back
Top