FIELD: protection of communication equipment against abnormal line voltage. SUBSTANCE: protective gear affording optimal protection between any conductors of N-wire line has first stage built around spark gaps connected to input leads and second stage incorporating protective members connected to output signal leads and distinguished by diode thyristor characteristics with operation delay time shorter than that of spark gaps of first protective stage. Protective members are interconnected in circuit forming N-angle pyramid whose vertex is connected to ground terminal lead. Fast-response second-stage protective members are first to respond to overvoltage and only after them first-stage members do so. Protective members on side edges of pyramid operate on occurrence of overvoltage between ground and any line conductors Protective members disposed on pyramid base are the only ones responding to overvoltage between line conductors. Number of protective members on side edges of pyramid is N and on its base, at least N/2 but not over N*(N - 1)/2. EFFECT: enhanced reliability of overvoltage protection for all line conductors in any combinations. 7 cl, 35 dwg
