The device is most often connected between a conductor to be protected and another conductor to be protected or to the ground. The current flowing through the device is almost zero until the voltage applied at its terminals exceeds a threshold value or reference voltage.
Beyond the threshold value, a current flows through the device in order to limit the overvoltage applied to the conductor. The current is discharged towards the ground.
The use of a device comprising two voltage-limiting passive components plugged in parallel between the terminals of the device is known from the document EP 07 16 493.
The device only requires one operational component to function. A display element reports the number of operational components. Thus, when one of the two components reaches its end of life and ceases to function, the device is still active thanks to the second component.
The device comprising a defective component must be replaced, but is still active within the time interval between the cessation of the component functioning and the replacement of the device.
This disposition greatly reduces the risk of failure of the device. However, according to the state of the art, the two components of the device are substantially identical.
Thus, the solicitation of each component is substantially the same: the risk of a simultaneous failure of the two components is to be taken into account. In fact, if the two components are defective, the device is no longer operational and plays no longer its role of protection against overvoltages.
In addition, the detection of the cessation of the functioning of a component by a user and the replacement of the device does not necessarily intervene immediately after the cessation of the component functioning.