Arrester disconnector

A means for disconnecting an arrester in anticipation of or after, a failure in order to prevent a permanent fault on the circuit and to give indication of a failed arrester. Note: Clearing of the power current through the arrester during disconnection generally is a function of the nearest source side overcurrent‑protective device.

Comment: Two types of devices are found on the market: One type includes a internal fuse or thermal cut‑off which opens, disconnecting the failed SPD component while leaving the load energized (protection is lost for the next surge but operation of the load is maintained). The second type includes a internal fuse or thermal cut‑off which opens, disconnecting the failed SPD component, and the load (protection is maintained but operation of the load is interrupted).

Source: UIE Guide to Quality of Electriical Supply for Industrial Installations, Part VI: Transient and Temporary Overvoltages and Currents