PZH HDT*/*B is a complex range of surge protection devices designed for the protection of data, communication, measuring and control lines against surge effects. These devices are recommended for use at the boundaries of LPZ 1-2-3 lightning protection zones according to EN 62305. All types provide effective protection of connected equipment against common mode and differential mode surge effects according to EN 61643-21. The rated load current of individual protected lines IL = 0,5 A. 1st stage is solved by using three-pole gas discharge tubes, 2nd stage by using transils. The number of protected pairs is optional (1-2). PZH HDT/*B is produced for nominal operating voltage within the range of 6V - 48 V.