In our design used TRIAC to control the load, As per the product field test setup i should short the neutral and earth connect together also the digital GND is connected with chassis.

The input AC power for TRIAC taken from the UPS (the power used for control circuit through DC power supply), when I load the TRIAC 500 watts my input power from UPS going for TRIP, due to the earth leakage current settings.

my questions are:

  1. Can I connect the AC INPUT power from raw GRID (without UPS) to LOAD the TRIAC? , Is it will affect or increase the earth leakage current or any damage will accrue?
  2. If I use isolation transformer to isolate the neutral and phase and secondary neutral and earth tie together, Is it will help ?
  3. Any alternate method will work out?


simulate this circuit – Schematic created using CircuitLab

  • 1
    \$\begingroup\$ "As per the product field test setup i should short the Neutral and Earth connect together ..." In general, neutral and earth are only connected at the supply transformer or at the building incoming supply point. To do so in your equipment is dangerous. Your user profile has no location information so we don't know what your local regulations are. "As per the product field test setup ..." What is this? Hit the edit link below your question to fix it up. \$\endgroup\$ – Transistor Aug 20 at 12:40

I'm having difficulty understanding your questions, but I think rather than answering the details I can address the overall problem:

Earth leakage protection is designed to disconnect power when small currents are detected flowing in the earth connection. The philosophy is that any current flowing in the Earth is a sign that current has "leaked out" of the normal active-neutral circuit. So the idea is that you make all intentional circuit connections to only active (phase) and neutral, but run earth nearby to "catch" any stray live conductors.

So when you "short the neutral and earth connect together", you can no longer use this protection scheme - normal currents will easily flow to earth and trip the earth leakage protection.

Earth leakage protection will only work if you deliberately do not connect any part of your main circuit to earth.


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