Rong Hua (Bianhuan) “50 Watt” Travel Adapter: not enough iron, for this “wattage”

In interesting find, Made in China, a 50 Watt travel adapter.

autotrans sc-20c a

autotrans sc-21c

autotrans sc-21c receptacle

autotrans plug

This is used to convert 220 V (despite the US plug!) to 110 V – same device also seems to exist for conversion from 110 to 220 V.

The build quality is exactly what you expect for less than USD 7. A crude plastic case, two screws, no protection circuits or fuses, and a rather small transformer.

autotrans inside

Total weight of the transformer – about 140 g.

Looking at some transformer tables, this is about 6-10 VA (=”Watt”, if you wish) nominal size. For autotransformers like this, the nominal size needs to be converted to the actual power rating, by using the conversion ratio (voltage ratio). P_nominal=P_actual*(1-voltageratio). I.e., for a 220 to 110 Volts transformer, the ratio is 0.5, and a 10 VA nominal transformer can handle 20 VA if configured as an autotransformer.

Quite obviously, 20 VA is not 50 VA – please use these these transformers with great caution, and only for really small appliances. Never leave it plugged in unattended, it might catch fire any time if overloaded, or if it fails!

2 thoughts on “Rong Hua (Bianhuan) “50 Watt” Travel Adapter: not enough iron, for this “wattage””

  1. So you say if you plug this in a 110V socket, it is safe to connect a 220V / 20 Watt appliance?

    1. Yes, a 20 Watt appliance will be safe. Anyway, these are travel adapters so maybe better don’t use it permanently.

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