This section of IEC 870-2 applies to telecontrol equipment and systems with coded bit serial data transmission for monitoring and control of geographically widespread processes. It is also a reference document for teleprotection equipment and systems and for equipment included in a distribution line carrier (DLC) system supporting a distribution automation system (DAS). This standard specifies, with reference to the various components of the systems defined above: 1) the characteristics of the power supply to which these components are connected during the normal operation; 2) the EMC minimum requirements, expressed in terms of immunity and emission test levels. With reference to EMC, the test levels have been selected among the classes established by the IEC basic publications on EMC, taking into account the particular environmental conditions under which the various types of equipment considered by this section operate; test procedures, test circuits and acceptance criteria are briefly indicated, making reference for detailed information to the IEC basic publications on the various subjects; reference is also made to basic publications on protection techniques and installation practices.