Impedance
The Ucc % parameter that governs voltage drop and short-circuit currents.
Definition
The impedance of a transformer, expressed as a percentage (Ucc %), represents the voltage drop across the transformer terminals when it delivers its rated current under short-circuit conditions. It is one of the fundamental parameters governing the electrical behaviour of the machine.
A low impedance (1–3 %) favours good voltage regulation and suits precision power supplies. A high impedance (5–8 %) naturally limits short-circuit currents, thereby protecting the downstream network — it is often required in industrial or medical installations.
At ABL Transfo, impedance is tuned from the design stage by adjusting the winding geometry and the interleaving of the layers. Each custom transformer can be specified with a precise Ucc % according to the requirements.
The ABL tip
Impedance directly determines the sizing of your protective devices (fuses, circuit breakers). A poorly specified Ucc % can lead to faulty discrimination or nuisance tripping. Tell us your network configuration and we will calculate the optimal value.
