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  1. JJ_Roy

    Wood Bridge Inspection

    I was just wasting my lunch break doing non-work related "nerd" things..... Like GIS.... It seems the bridge must be truly private because the one I think it is isn't in the MassDOT Bridge Inspection Management System.
  2. JJ_Roy

    Wood Bridge Inspection

    I thought it was like a typical HOA for some residential neighborhood. But it sounds like they have enough money.... so a $30k/resident one-time "special assessment fee for the 100 or so homeowners should be no problem to replace the bridge when it fails. I think this is the bridge and it has a...
  3. JJ_Roy

    Wood Bridge Inspection

    There's others here that could probably give a better "guestimate", but this is probably a multi-$k job. Especially if they're looking for a formal report with repair schedule and indicative estimates. All I know is HOA's aren't too keen on spending money that doesn't give them instant...
  4. JJ_Roy

    Wood Bridge Inspection

    I worked on a project some time ago in southeast MA to move a superload across a private bridge and the load insurer required it to be inspected before the move. I believe our company used Steer (sp?) Engineering from RI to do the inspection and write a report on short notice. None of the...
  5. JJ_Roy

    Transformer test report - zero sequence values

    The ohms are probably percent (0.393%), so your X/R would be = 20.6 What's your Z1%??? A check would be Z0% is approx. 90% of Z1% but others may disagree.
  6. JJ_Roy

    Custom ONAF2 Rating

    I don't think I'd argue too much with sizing the xfmr for the max real & reactive power the transformer might see. If you had a friendly manufacturer rep, (as bacon noted) then maybe you could get a memo stating the xfmr is adequately sized for the potential charge/discharge cycle(s) for the...
  7. JJ_Roy

    Custom ONAF2 Rating

    I'm assuming the system impact study thermal violation is for a "N" condition and not a "N-1" or "N-1-1". If it's for a "N-" condition, I've seen typical emergency loadings for 115/34.5kV xfmrs at 115% [Rate 2] and 140% [Rate 3] above the normal (highest) MVA rating [Rate 1]. How close are...
  8. JJ_Roy

    Custom ONAF2 Rating

    There's a lot of stuff that goes into transformer rating (winding materials, winding design, oil flow within the windings, etc.) so I'd be careful assuming you can increase the top rating without talking to a manufacturer. Just curious, is there a reason you don't want to increase the base rating?
  9. JJ_Roy

    Digikey Alternatives

    I used RS Americas when they were formally know as Allied Electronics. You could buy a single component like one resistor... But it was cheaper if you purchased 100 resistors..... They also had a really good selection of items as well.
  10. JJ_Roy

    Temporary Mobile Substation Grounding and Fencing Considerations

    Check out IEEE Std 1268 - "Guide for the Safe Installation of Mobile Substation Equipment"
  11. JJ_Roy

    Impact of EMF generated by Subsea HV Power Cables on the performance of FOCs

    As waross said it would probably cancel out.... if the crossing is truly at 90 degrees. You probably need to do some analysis with an electromagnetic software like SES CDEGS to show there is no issue. I'd discuss with the FO cable operator how the repeater power works and then go from there to...
  12. JJ_Roy

    photovoltaic dust accumulation

    "NERL Scientists Studying Solar Try Solving a Dusty Problem" https://www.nrel.gov/news/features/2021/scientists-studying-solar-try-solving-a-dusty-problem.html There are a couple of companies out there who have commercialized a product discussed in the NERL article.
  13. JJ_Roy

    Question about LTC Transformers

    You need to consider the "steady state" reactive power capabilities as well. Below is a clip from the ISO-NE Planning procedure 5-6 regarding reactive power capability testing. (FYI: it says wind park but it actually applies to all inverter-based generation.) I've (poorly) highlighted the...
  14. JJ_Roy

    Question about LTC Transformers

    Yes. Compliance with FERC 827 requires the reactive power capabilities to met at the high side of the station transformer. Some interconnections requirements say it's at the point of interconnection (POI). As warross noted, the LTC could have a significant impact.... I'd check with the...
  15. JJ_Roy

    Jersey Barrier Anchoring Advantage

    The utility I work for has lots of electric substations that are subject to vehicle "incursions". Some are at the edge of parking lots, some are next to highways, or on city streets. They employ everything from bollards to guardrails to cable barriers (...
  16. JJ_Roy

    open delta 3 phase voltages - 2 single phase transformers

    It might be a "high leg" as jraef pointed out..... Especially with the four secondary conductors. But I'd probably ask what the intent is.
  17. JJ_Roy

    Nuisance tripping in Sepam T40

    I had a similar issue with a dry contact from a transformer bucholtz or beta relay. We put loading resistors across the input at the opto board and it solved the problem. I remember making a simple circuit calculation using the opto board input impedance and pick up voltage to determine the...
  18. JJ_Roy

    Help calculating voltage drop through storm water

    During my time as utility district engineer in a coastal area in the northeast, there was a peninsula with a few hundred customers which was subject to flooding during nor'easters. The peninsula had only one road in and out. If the Fire Dept. had to do water recuses they'd request the power be...
  19. JJ_Roy

    open delta 3 phase voltages - 2 single phase transformers

    Probably some very bad voltage. There are lots of things wrong with the drawing including xfmr on the right appears to have only one secondary connection and the "X" bushing nomenclature doesn't look right. But the drawing is probably trying to go for a 3ph 240V open-delta maybe? This is a...
  20. JJ_Roy

    Required Vehicle Clearance Distance from Substation Fence and Relevant Code References

    There is no requirement that I'm aware of regarding the minimum distance for vehicles from a substation fence. The fence should meet NESC Rule 110 to maintain clearance for unauthorized persons. If your substation lives in "NERC land", then it may be subject to the NERC Physical Security...

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