relay questions and answers here.

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Comments: 4
  • #1

    Jim (Tuesday, 12 February 2019 02:00)

    Drawout vs hard wired relays
    Manufactures moved to hard wired relays when the transition from e/m to electronic occurred. This has been the source of great pain for users. A typical modern microprocessor relay will have to be removed for update or repair several times during it's lifetime. The labor to remove and replace will far exceed the cost of the relay. In some cases important transmission lines may need to be removed from service putting the system in jeopardy. Customers need to push manufactures to build a product that is serviceable in a modular fashion without removal of the relay case. In this age a relay should be serviceable in minutes with a couple of man-hours labor rather than days and hundreds of man-hours.

  • #2

    Jim (Tuesday, 12 February 2019 15:06)

    Relay design: one processor vs multiple
    Early relays had small relatively slow microprocessors that used thousands of lines of code. Most all those lines were dedicated to protection. Current designs use much faster and capable processors that do many additional tasks over and beyond just protection elements and require hundreds of thousands of lines of code. The communications tasks alone far exceed the protection tasks in code lines and processor burden. Good design practice demands that multiple dedicated processors be used so that the main critical function of the relay, protection, be straightforward and as simple as possible to design and maintain. It is a travesty that a change in communications programming on a firmware upgrade could cause the whole relay to hang. Each section of the relay should be its own island unaffected by trouble and bugs in the other sections. All code has bugs. It's just a matter of time before they manifest.

  • #3

    Jim (Tuesday, 12 February 2019 16:25)

    Opinion: Time domain transmission line relay
    This relay attempts to measure the elapsed time on traveling voltage waves to achieve faster tripping times. I'm not sure there is enough real world experience with this method for my comfort. Instrument voltage transformers were not designed with this relay in mind. There may be significant errors causing false tripping especially on medium length and short lines. I would take a wait and see approach letting others bear initial development and revision pain. What is the price/risk of gaining a few milliseconds?

  • #4

    Jessica (Thursday, 11 July 2024 10:22)

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