Which circuit breaker to install? ABB B16 C or ABB B 20 C?

Good afternoon, Alexander.

Of course, it’s better to ask a question to draw a diagram - a graphic image excludes interpretation.

I understood from your question: a wire was sent from a 220 volt shield to an outlet. An electric stove and an autotransformer are connected to the outlet through a double / tee. The machine protecting the autotransformer is installed in front of the autotransformer, that is, after the tee / double.

For further decipher the name of the autotransformer - AT-220-100-1-50:
- AT - understandable;
- 220 volts - primary voltage;
- 100 volts - secondary;
- 1 kVA - rated power transmitted by the transformer;
- 50 hertz - AC frequency.

The main parameter for you when choosing a circuit breaker is the transformer power of 1 kVA. Roughly speaking, you can assume that an autotransformer can supply electricity to a 1-kilowatt set of power receivers.

The current flowing through the primary winding is determined as follows: 1000 watts / 220 volts = 4.5 A.

Thus, you need any machine that cuts off the current greater than 4.5 A. The rating of "ABB B16 C" is too big, for "ABB B 20 C" even more. Any switch rated 4A is better, for example, "ABB S201M 1P 4A".

If, nevertheless, you meant the protection of the wire “electrical panel - outlet”, then the machines that you “looked after” would also be suitable. Let me explain: for example, an aluminum cable AVVG 3 * 4, thrown through the air passes 30 amperes. Thrown in the floor will miss 20% less.