ABNT, through its technical standard NBR 5458 (1981), defines the transformer as: “A device that, through electromagnetic induction, transfers electrical energy from one or more circuits (primary) to other or other (secondary) circuits, using the same frequency, but usually with different currents voltages and currents. ”
For this component of the electrical network four points must be considered: – the input voltages;
– about to leave;
– the type of winding;
– the power and shape of the core.
As for the input and output voltages, the transformer may be of the voltage lowering type or the voltage lifter. The transformer will be voltage lowering when the input voltage is greater than the output voltage, and will be voltage boost when the situation is reversed.
Protection systems in distribution networks should include the following points:
– Protection in materials and equipment against damage caused by short circuit;
– Improvement and reliability of the distribution circuit, by reducing the possibilities of the effects of a fault to the smallest possible part of the circuit in the shortest time; with this, there is the decrease of the power involved and number of consumers reached.
– Rationalization of the cost of protection schemes that should not exceed the benefits arising from their use.