SAFETY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a safety device H for protecting the intrusion of a surge voltage and a surge current introduced to a subscriber line, in which constant current diodes 11 and 14 are connected to the subscriber line. SOLUTION: Communication equipment can be protected from a surge, a DSU(digital service unit) stack of a terminating device does not occur, and an ISDN can be left in a satisfactory state because current caused to flow into the terminating device can be made constant regardless of the magnitude of the surge.