The new European Normative EN 50550, regulating the protection against transient and power frequency overvoltages, has recently been published. The mentioned standard defines as power frequency overvoltages (POP) those whose duration is relatively long (several cycles) and may cause damages to the installation and to the electrical equipment.

As a summary of the standard specifications, overvoltage protectors may actuate on circuit breakers or on residual current devices. It is essential that they act with a delay in order to avoid incorrect breaks. The standard fixes a minimum non-actuating time of 3s for 275V and a maximum break time of 0,2s for 400V.

The ATCONTROL power frequency overvoltages protectors of Aplicaciones Tecnológicas, S.A. accomplish those specifications, with 3 possibilities for installation:

– ATCONTROL/B, which actuates on any shunt release.
– KIT ATCONTROL/B, which includes the circuit breaker.
– ATCONTROL/D, which actuates on any 30mA residual current device.