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I have an ignition system used for some application.

During the testing I found that spark plug is producing EMI due to spark occurrence and high voltage is traveling through the wire.

So to suppress the noise signals, I connected the secondary end connection to the earth (through electrical junction box.) But when I turned on the setup, the equipment (RPS) which connected on the same line (connected on the same junction box) is disturbed (glitches in display,) within few seconds RPS is blown off (something is burned inside the RPS).

I am not able find the exact problem but during the testing I tried moving the earth connection near to the secondary end, suddenly an arc is jumped from secondary end to earth connection.

  • \$\begingroup\$ What does "RPS" stand for? \$\endgroup\$
    – JRE
    Feb 16 '19 at 12:22
  • \$\begingroup\$ @JRE Regulated power supply \$\endgroup\$
    Feb 16 '19 at 12:28
  • \$\begingroup\$ The other side of the "Junction Box" is your Mains power? \$\endgroup\$
    – Tyler
    Feb 16 '19 at 12:30
  • \$\begingroup\$ @Tyler yes connected to mains supply \$\endgroup\$
    Feb 16 '19 at 12:33
  • 2
    \$\begingroup\$ Automotive ignition coils have an internal connection between the negative ground sides of the primary and secondary coils, and then to the metal case. They also use a high voltage wire with built-in suppressor resistance. Or you could add a high-voltage series resistor in the meg-ohm range. \$\endgroup\$
    – John Canon
    Feb 17 '19 at 0:10

It appears that, with the hot end of the secondary earthed, the high voltage (>12kV) reversed through the primary into the regulated power supply resulting in the transformer getting burnt due to insulation failure.

It is imperative that you disconnect the power supply from the mains immediately. With the insulation having failed, it would be extremely hazardous to handle it.

Take care!


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