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  • Users: stevenal
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  1. stevenal

    Nuclear Now

    Just watched the Oliver Stone film. Impressive treatment of the subject. Available pay-per view. I recommend it.
  2. stevenal

    Transmission ground distance relaying with distribution underbuild

    How do you handle the mutual coupling? Ignore it. Carefully model the distribution circuit(s) and mutual(s) in your fault program. Model just the distribution neutral in your fault program. Measure the line impedances including the mutual coupling with test equipment. Use actual fault data to...
  3. stevenal

    Wait to reenergize following lightning?

    A rare thunder windstorm caused both 230 kV lines feeding a transco substation to trip open, causing a big outage. Transco found and removed a tree in one of the lines and stood by to reenergize. The wind had died down, but the lightning continued. Transco evidently has a strict policy of not...
  4. stevenal

    transformer for connecting 34.5 to 12.47 kV

    All, I'm looking to specify an 8 MW transformer for connecting two four wire distribution systems that are in phase. This can be accomplished with an auto-connection, but will this be the most cost effective way to go? I know that's commonly the case at transmission voltages, but unsure at the...
  5. stevenal

    PV backfeeding the grid

    Situation: Utility customer meter is occasionally registering reverse power flow and PV panels are visible on the property. The customer has not gone through the net-metering approval process, so the utility has no record of the installation or knowledge if NRTL products were used, what...
  6. stevenal

    An electric utility microwave site hut. Regulatory hole?

    The NEC excludes equipment under the exclusive control of electric utilities used for communication. The NESC speaks of overhead and underground communication line installation, but I fail to see mention of any installation requirement for the indoor equipment installation at a microwave site...
  7. stevenal

    automatic splices

    Following a recent failure (that preceded last week's ice storm), I've been looking into these things. [ol 1] They reduce the allowable tension to 60% of that of an un-spliced conductor. They need at least 15% of the conductor breaking strength to function. [/ol] Does this 15 to 60% window seem...
  8. stevenal

    Do I need a tertiary?

    This is related to my other question. I was incorrect on the voltage, neighbor has 24.9 kV, ours is 12.47. Both are grounded wye systems feeding unbalanced loads. The 60 degree phase shift can be accommodated with a Yy6 connection by choosing the proper bushings. The transformer size is 3000...
  9. stevenal

    Zig-zag 60 degree phase shifting transformer

    The situation: Neighboring utility uses the the same voltage wye grounded system as we do, but is shifted from us by 60 degrees. In order to allow a closed transition transfer, our neighbor is proposing to use a delta/zig-zag phase shifting transformer. I know zig-zags are used for grounding...
  10. stevenal

    RUS Bulletin 1724E-200

    Says to add two bells for dead-ends, but fails to indicate why. It goes on to speak of leakage distance, explaining the horizontal strings wash better and are less susceptible to contamination leakage, so this does explain the difference. Does anyone know why to add bells at dead-ends, and does...
  11. stevenal

    Oil to oil bushings

    A bushing on a '74 Westinghouse faulted recently. The transformer is fed from a 69kV underground line. An oil filled compartment attached to the transformer houses the cable terminations and the exterior portions of the oil to oil bushings. I cannot find a record of any pf testing on the...
  12. stevenal

    Loss of phase or loss of three phase generator transfer

    An office building served three phase through a wye/wye service transformer has a standby generator and UPS system. When service is lost, the UPS keeps the critical loads up while the generator cranks and the transfer takes place. Over the weekend, a primary phase was lost. The UPS kept the...
  13. stevenal

    OC device in the neutral

    thread238-474408 It happened again. Watch these manufacturers.
  14. stevenal

    Help understanding a GE tapchanger

    https://res.cloudinary.com/engineering-com/image/upload/v1671143998/tips/DOC005_cvrzwk.pdf Can anyone help me understand the purpose of the 84X/TDO normally closed contact and the diode on the right side of this drawing? The two resistors brake the motor once it gets on step, but the midpoint...
  15. stevenal

    Generation transfer-tripping

    A radial line feeds an industrial site that has generation partially offsetting their load. Synchronizing equipment is at the generator breaker only. It is decided the sourcing substation should send a transfer-trip signal to the generator breaker when conditions dictate. Would you source this...
  16. stevenal

    Internal LTC VT

    We have a single substation LTC equipped transformer that has an internal LTC VT. Is anyone familiar with these VTs? Is there simply an extra lead on the bottom end of the X1 and X0 bushing? Is the VT mounted on top of the core? Thanks.
  17. stevenal

    Ground loop around pad mounted distribution transformers and other medium V metal encased equipment

    My group installs these in order to control touch potential. It's been suggested we are alone in this endeavor. Anyone else doing this?
  18. stevenal

    Online oil filtration system for reactive LTC

    We've used online oil filtration systems for our resistive LTCs with good experience. Lately, it's been suggested that we extend maintenance intervals on our older reactive LTCs by retrofitting filtration. My concern is the filters will load up so quickly they will continue to be high...
  19. stevenal

    Cal Fire

    Anyone here deal with or have familiarity with the code?
  20. stevenal

    delay in IEC 61131-3 structured text

    I'm attempting to delay program execution in a user logic program in an SEL RTAC. This is what I came up with: VAR Pause:TON; END VAR //Program Pause Pause(IN:=TRUE, PT:=T#100MS); //start timer WHILE NOT(Pause.Q) //loop until timer expires DO...

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