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  1. rowbotth

    Transformer differential protection

    Check the polarity of the wiring into your differential relay. It sounds like you have reverse polarity at a CT. Generally, 15% of rating is where these relays will pick up. "Differential relays do not mis-operate. The CT wiring into them is wrong, if there is not a fault." This...
  2. rowbotth

    Arrester selection for system with neutral grounding resistor

    The NGR is ALWAYS used to limit Ground Fault Current. It is always installed between the star point of the transformer (or generator, or source of power) and ground, or earth. As it is installed at this location, the maximum voltage which can be impressed across it is the Phase to Ground...
  3. rowbotth

    Lightning problems

    You have two items - the problem you asked about, and some grounding issues which are (according to our experiences) not part of this problem, but should be changed. From a course I took from the folks at PTI, it appears that when you get a lightning strike and you have a wire above the phase...
  4. rowbotth

    Transformer Location

    The only thing that comes to mind is one of transferred potential. If your transformer is part of a substation, you might be concerned with the fact that you have a current-carrying conductor buried within the substation grid, and would have something which may carry fault current to a remote...

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