| 摘要 |
The invention is based on an overvoltage protection apparatus which consists of at least one varistor and a spark gap which is connected electrically in parallel with said varistor and is preferably capable of carrying lightning current. This may be an air sliding-flashover spark gap whose air flashover point is located outside its electrodes. A monitoring device (5) for the maintenance of the current/voltage characteristic (12) of the varistor and for disconnecting the varistor in the corresponding fault key is provided in the branch of the parallel circuit containing the varistor (4). Thus, even if a leakage current occurs in the varistor, the operation of the spark gap is not adversely affected, as a result of which the operation of the overvoltage protection apparatus is maintained despite this defect. <IMAGE> |
