C37.93-1987 - IEEE Guide for Power System Protective Relay Applications of Audio Tones over Telephone Channels
Description: The guide contains information and recommendations for applying audio tones over telephone channels for power system relaying. Included are sections on transmitting and receiving equipment, leased telephone channels, application principles, installation, and testing. Reflected in this work is the knowledge and experience of equipment manufacturers and telephone companies as well as that of power utility users.