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  1. System Protection

    SEL 651 indicator light showing open when closed.

    The LED should be programmable, so it was connected to a "b" contact you could change the logic to suit.
  2. System Protection

    Concrete Aggregates: Crushed vs Natural(Rounded)

    This is way outside my wheelhouse, but it did remind me of a recent video by Practical Engineering on Youtube. Some interesting comment as well on the video.
  3. System Protection

    Two-slider crank mechanism

    https://patents.google.com/patent/EP3530879A1/en?oq=3530879
  4. System Protection

    Exceeding Metering Class CT Burden Rating

    In practice maybe. Technically I don't think there is a provision in C57.13 that requires accuracy above the standard burden though. What does the CT manufacturer documentation say?
  5. System Protection

    EN 10025 S235JR Plate in US

    I'd try contacting Leeco.
  6. System Protection

    Bluebeam.....

    Its easy to use. Common for non CAD folks to collaborate as multiple people can markup the same PDF simultaneously. Comes with lots of PDF tools as well, merging/splitting, measuring etc. If you know CAD already you may find it limiting.
  7. System Protection

    Industrial LED lighting on a dimmer

    https://assets.lutron.com/a/documents/controlling%20leds%20webinar.pdf You could try calling Lutron. I have linked a webinar on LED lighting from them. It briefly discusses dimming.
  8. System Protection

    Explanation for Importance and/or application of the "3*Zero Seq Current" for LG and LLG F

    It "flows" in phase and equal magnitude through all the sequence networks. I1=I2=I0 The current does not flow equally through all the phases (A,B,C)
  9. System Protection

    Air leaks through 3D Printed PLA

    A video from CNC Kitchen on YouTube also comes to mind. He was attempting to print translucents as clear as possible. I believe it resulted in very strong layer adhesion. The technique may work here. Can't remember exactly what parameters he used, maybe slower and hotter. I'll see if I can...
  10. System Protection

    Air leaks through 3D Printed PLA

    Have you tried chemical smoothing? Not sure if it would work but may be worth a shot. Or leave it hollow and fill with epoxy. I believe there is an infill pattern that would allow an epoxy fill in between walls.
  11. System Protection

    Explanation for Importance and/or application of the "3*Zero Seq Current" for LG and LLG F

    Yes, the 3I0 value would be used to set your ground relays. Could also be used in ground grid studies, ground potential rise calculations, etc.
  12. System Protection

    Current transformers- over voltage on open circuiting secondary

    Only seen one open circuited for a brief moment. C800s are pretty good at letting you know they are open. (Terminal blocks inside control house melted together) No known permanent damage to the CTs. Tested okay afterwards. I've heard of smaller CTs being left open for a long period of time...
  13. System Protection

    Obtaining a GC license? Anyone here done that?

    Edit. Didn't see this was in mechanical.
  14. System Protection

    DIY Circuit Breaker Current Injection Testing Kit

    How about a Variac in between your voltage source and the 230V input of the 230/12 transformer? Then an ammeter on the low side of the 230/12V transformer so you can dial in the current.
  15. System Protection

    Hello, I need to change somme sett

    What relaying function is it performing? Is it redundant? I don't recall any inadvertent operations due to a settings change on a relay. I still prefer to have them isolated or out of service for settings changes though. That way you can test the changes, and make sure you got everything...
  16. System Protection

    Hello, I need to change somme sett

    A REL-316? Is it redundant? If it is redundant, I would just cut it out prior to making your changes.
  17. System Protection

    OHL 220KV Accident

    It's not possible to accurately gauge the strength of the short circuit. You would need to talk to the utility that owns the line. I'm not a lineman so I won't comment too much on the required outage time but the damage doesn't sound too bad so likely less than one day. Was the metal structure...
  18. System Protection

    CT's in parallel question

    I have never heard of a 2.5A nominal CT. Are you sure you don't have a 5000:5 CT? It's the same ratio as 2500:2.5 Two 5000:5 A CTs with 2500A primary in each phase with a SERIES connection will result in 2.5A flowing in the secondary. (With half the voltage across each CT compared to a single...
  19. System Protection

    CT's in parallel question

    Are you sure your CT secondaries are in series and not in parallel?
  20. System Protection

    ABB REF615 TON(1) Timer

    Do you have the latest firmware? I'd check that first. I haven't worked with ABBs in a long time and never with that particular relay but the logic should be customizable, at least the 670 series was. Can't remember if it's done in PCM600 though or different software.

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