Telephone junction box

:: PK1-OVP3 is a protection box designed for connection of telecommunication line with subscriber installation.
It provides protection of all subscriber devices connected from overvoltage and overcurrent generated by atmospheric discharges, electromagnetic induction of nearby power installation and cross-contact between telecommunication and power cable.

:: This protection is realised with 5-pole module for serial connection on telecommunication lines (e.g. telephone pairs). Two poles are connected on line (cable) side, the other two on subscriber equipment side and the fifth pole is grounded.

:: This module provides two-stage overvoltage protection: coarse protection using three-pole Gas Discharge Tubes (GDT) with fail-safe clip, and hyper-fine protection with thyristor diodes.
Overcurrent protection is realised by Positive Temperature Coefficient (PTC) thermistor.
Following the appearance of surge, hyper-fine overvoltage protection reacts first, (response time less than 1 ns) limiting overvoltage. After a few miliseconds PTC starts limiting overcurrent, especially in case of cross-contact between telecommunication and power distribution cable, operating as a resettable fuse.
Resettability can be provided after more than 24 hours of cross connection with I=23 A, if necessary.
That means PK1-OVP3 is completely self-maintaining protection according to required tests in ITU-T K.20 and K.21 Recommendations.

Download PDF »