Surviving lightning strikes

Today I went into the lab to repeat some surge tests that let the smoke out of Argon’s on-board voltage regulator the last time. This time some circuit modifications were made as attempts to enhance the surge voltage & current handling. Surge test attempts to emulate a lightning strike.

Total of 12 a bit different surge pulse tests cases had to be carried out to meet the EN 61000-6-2 and EN 61000-4-5 industry standards. In the list below are the open circuit voltage and series resistance that are shot to the target voltage supply lines:

  • + and – 500V 2Ω between 24V and 0V (DC supply)
  • + and – 500V 12Ω between  +24V input and chassis (DC supply)
  • + and – 500V 12Ω between 0V input and chassis (DC supply)
  • + and – 1000V 2Ω between L and N (AC input)
  • + and – 2000V 12Ω between L and chassis (AC input)
  • + and – 2000V 12Ω between N and chassis (AC input)

The surge tests are typically more difficult to pass than ESD & EFT due to high injected energy and currents. For instance 500V and 2Ω  produces current of 250A and 1000V 2Ω yields whopping 500 Amperes. That will heat up the overvoltage protectors quite extremely and weaker components simply explode.

Now all tests passed without damage and motor was servoing simultaneously through the whole test. Changes will be brought to the PCB design which makes a big step closer to the final design.

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