Lightning Current Estimating and Protective Design of Smart Water Meter´s Data Acquisition Card

There are two ways to transmit signals which are RS-485 signal and a kind of special signal in the new type of Smart water meter´s data acquisition card. The work on design of the Surge Protection Device (SPD) is made by estimating the lightning current which travels in signal wires, comparing the capacity of restraining interfering signal between balanced signal and unbalanced signal, in according to JJG162-2009. A lot of experiments were tried with LST-6kV/3kA and ICGS, which could approve the feasibility of this design, after these approaches, some suggestions are made which enjoy great practical engineering significance.