I got a 3000watt step down transformer(https://www.amazon.com/gp/product/B07LCSTP24/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1) to power my 1500 watt Ninja blender I got from US to run in India.

For some reason, whenever I plug the transformer in, the circuit trips. To be noted, that I got a similar step down transformer but a 1500 watt one to power my TV which doesnt trip any circuit.

Any clue why this is happening? Does the power rating of transformer cause this issue?

  • US kitchen appliances are quite small compared to 5-continent power circuits. (which typically permit 3100+ watts). Either you have other heavy loads also being used at once, or there's something special about this breaker that we need to know about. Can you describe it further? Which one is it? Does it have a TEST button? May 30 '20 at 12:37
  • It does. There is a TEST button with the switch sayig 240-415v. Not sure if this helps. May 30 '20 at 13:48
  • Also, while going through this forum, i realized that the adapter i used was not 3 pin, but a 2 pin. So there was no earth. Transformer' plug is a standard US 3 pin plug. Can this create any issues ? May 30 '20 at 13:53
  • Can you post photos of the breaker that's tripping? It sounds like you're tripping a RCD/RCCB, but I want to make sure... May 30 '20 at 14:56
  • @ThreePhaseEel there you go imgur.com/a/N5VH66Z May 30 '20 at 16:24

All transformers are essentially a "short circuit" for the brief instant that they are energized, because it is the interaction of the magnetic fields that impedes (resists) the flow of current, and for a brief instant, there is no magnetic field yet. This is called "inrush current" and can exceed 10x the rating of the circuit breaker. Often that inrush is of such short duration that it is too fast for the breaker to react to, but if it is TOO high, then it can trip the breaker. Because of this, MCBs, like the ones you show, can be purchased with different "trip curves". The ones in your photo are "C" curve, which are for general purpose use. For feeding a transformer, you want a "D" curve (so it would say D10 instead of C10). A D curve breaker will allow up to 14x the rating for the instantaneous trip function, which is designated for handling transformer inrush.

When the smaller transformer worked, it was because >10x the transformer inrush current is still less than the breaker instantaneous tripping point. You could get a similar effect by using a larger breaker, but then you would have to change the wire.

  • Thanks, informative. Any explanation into why it was running before and suddenly stopped running? To be noted, i did change the incoming setting of transformer from 220v to 110v and then reset it to get it running. Was that the reason it didnt trip immediately? May 31 '20 at 8:26

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