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  1. OffTap2020

    Close/open command during OCB timing test results in NO data ( ZERO)

    It was a bad aux relay. But was intermittent, so it made it difficult. All linkage and mechanisms were tight and properly connected. Thx for your insights. OT2020
  2. OffTap2020

    Close/open command during OCB timing test results in NO data ( ZERO)

    While performing routine timing tests on a 15kv 1200 amp OCB, bot the close command test data and the open command test data was well within trending perimeters. But when performing a close/open command, ( simulating closing into a fault), all data came back 000.000 on ALL poles, and on both...
  3. OffTap2020

    Replacement for section of main DC cable in substation- Do you have a cable preference?

    Looking for some seasoned advice on choosing a single conductor cable for a DC replacement project. Cable will be 2/0 copper, will be in out door cable trench( exposed to weather) in conduit ( separate) , and also run inside in cable tray. I have checked a few vendors ( Okonite etc)...And I...
  4. OffTap2020

    Negative power factor readings on SF6 CB

    Thank you for the information. OT
  5. OffTap2020

    Negative power factor readings on SF6 CB

    Recently on our 72K Dead Tank( Alstom) SF6 CB's, we have been getting a rash of negative readings. We perform GST, GST (guard) and UST tests. Some of our tests are coming back negative Pf, and negative watts. This has happened a couple of times in the past, and when tested a year later, the...
  6. OffTap2020

    Gas in oil analysis, high acetylene, how dangerous?

    If it retests AGAIN at 102 ppm of acetylene. Switch it out immediately. You have a bomb on your hands. OT
  7. OffTap2020

    CFR 112.1b Secondary containment of oil filled transformers

    "I'm not sure why you expect to see recent construction. The SPCC rule may have been modified recently, but it has been around for a while now; and containment or equivalent was considered good engineering practice prior to that. Containment is generally underground, and not very visible from...
  8. OffTap2020

    CFR 112.1b Secondary containment of oil filled transformers

    " I'm not sure that secondary containment is the only acceptable countermeasure. ". Could you elaborate on that? OT2020
  9. OffTap2020

    CFR 112.1b Secondary containment of oil filled transformers

    I have searched for like threads, but have not found anything current. Based on the current CFR Title 40 dated February 12, 2012, if a transformer of sufficient size is located in an area that is miles from a navigable water source ( city area), would a SPCC still be sufficient? The document...
  10. OffTap2020

    PT Connection Question

    Looks like a one secondary, one tertiary winding. OT
  11. OffTap2020

    Cooper Single Phase Transformers

    Thank you Waross and Pwrengrds. I agree that the pad are in an odd place. But they are factory installed, they came right from Cooper The portion that looks rusted is actually just the paint peeled back because of the heat. We should hear back from Cooper tommorow morning. A contact at...
  12. OffTap2020

    Cooper Single Phase Transformers

    Here is also a picture showing these pads between the bushings.http://files.engineering.com/getfile.aspx?folder=954f7a31-37b9-4a92-b51e-12e947def89c&file=IMG_0527.jpg
  13. OffTap2020

    Cooper Single Phase Transformers

    Recently we received quite a few Cooper 997kva 7200-277 single phase transformers, for use in some of our larger customer subs. Some have been installed, and when IR scanned, they show excessive heat( 300f) right between the secondary bushings. In this exact area between the bushings, and on...
  14. OffTap2020

    DGA sample confusion

    We don't as a rule document the ambient temp of the day, while sampling. I guess we should. Then again, the outside testing company didn't document that as well. But I'm sure, with some researching, and knowing the dates all samples were taken, I could probably get that info off the net for...
  15. OffTap2020

    DGA sample confusion

    Recently a 15mva transformer at one of our small substations was sampled for DGA. Our sample showed 6ppm for moisture in oil(D-1533B) and 7ppm for % saturation at top oil temp. The interfacial tension was 39.8 One week BEFORE, an outside testing company, using the same testing lab, sampled...
  16. OffTap2020

    aluminum to copper connection at CB

    Only one set of nuts and bolts. Total. OffTap
  17. OffTap2020

    aluminum to copper connection at CB

    Steelerfan, Yes, we've used those in the past, on some of our smaller ocb's that were less then 600amp. Unfortunetly, this CB requires parallel taps of 1590 ACSR or AAC. Might be tougher to make those connectors work. I ordered the transition pads from Hubbell, and received them already...
  18. OffTap2020

    aluminum to copper connection at CB

    Stevenal, Which part of the transition piece do you feel increases the possibility of a failure? Is it the molecular bonding of the copper and aluminum plate? Or do you mean that 1 connection is better then 2? Removing the (3) 3000 amp switches from the rack and sending them out to be...
  19. OffTap2020

    aluminum to copper connection at CB

    Laplacian, Yes, that is exactly what I'm looking for. So far, I have not been able to find them on the Hubbell site, but I will continue looking. I hope they are available in less then the usual " 8-12 weeks" we've been dealing with lately. OffTap
  20. OffTap2020

    aluminum to copper connection at CB

    Does anyone have a suggestion regarding this..? 1590 acsr taps from 16kv isolation switch to bushing connectors at top of outdoor vacuum CB. The old isolation switches have copper "pads", not tinned or bronzed. The 1590 lugs are all aluminum. The existing connection was made up with similar...

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