WHY USING PROTECTION?

When a surge voltage is produced in an electrical conductor, then an overcurrent with a magnitude of several kA is lead to earth.

In order to avoid that the overcurrent destroyes the equipment connected to the electrical system, a protector is installed in front of the equipment. The protector derives the current generated by the surge voltage directly to earth without making it pass through the equipment.

Maximum current (Imax): The maximum current which a protector may derive to earth one time without suffering damage.

Rated current (In): The value in amps which the protector is able to derive 20 times without suffering damage.

Residual voltage (Ures): When deriving current produced by surge voltages, then between both ends of the protector a voltage is produced due to the protector's impedance. Ures=I*R.

Protection level (Up): This is the voltage appearing between both ends of the protector when the current In circulates through it.