PZH HDT*/A is a 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 = 5 A. 1st stage is solved by using three-pole gas discharge tubes. The number of protected pairs is optional (1-2). PZH HDT*/A is produced for nominal operating voltage of 48 V.