Low voltage transformers are designed to supply electrical devices with the required rated voltage. Transformers from the ETITRAFO group do not have internal short-circuit protection, so an appropriate external protection must be used. The rating plates of transformers show the value of the required rated current of the fuse protecting the transformer against the effects of a short circuit. The protection of the primary side of the transformer should be selected taking into account the surge current generated when the transformer is switched on and which may reach a value of approx. 25 times higher than the rated current of the transformer in approx. 10 milliseconds. The most suitable protection for the transformer in this case is a gG or aM slow-blow fuse or an MCB automatic protection (overcurrent circuit breaker, e.g. ETIMAT) with short-circuit characteristic D. Protection of the secondary side of the transformer should be implemented with a fuse with gF or gG characteristics or with a circuit breaker overcurrent device (e.g. ETIMAT) with B or C short-circuit characteristics.