Question

How to detect and arrest single firing of SCRs?

When SCRs are used for driving inductive loads like transformers (In welding applications) or motors, and controller is controlling by random complementary firing angle method, is there any way to detect from controller side that in a pair of SCRs (2 or more used in the circuit), if any SCR is short circuited or open?
May 20, 2012

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All Answers (4)

  • Jaime Chiquita
    Tne coils as inductance, it keep the SCR loaded a litle after power off the system. try connect a resistor in it to keep the fase clean.
    May 22, 2012
  • Anil Velhankar · Weldcon India Pvt. Ltd.
    @ Jaime, Thanks for your comments.
    I already connect such resistor for damping in my system.

    But the question is, how will I detect if any of the two anti-parallel SCRs become open or short?
    I need to sense the same from power connection side.
    May 23, 2012
  • Kun Wei · Rockwell Automation
    To detect the phase current may be a solution.
    May 24, 2012
  • Toby Ding · Cape Eleuthera Institute
    SCR always short when it failed, so the current of the SCR will much more than usual.
    May 24, 2012

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