Microwave Relaying Extended with High-Frequency Cable

The conversion of 2-terminal 138-kv transmission lines to multiterminal lines requires extension of microwave relaying communications to retain high-speed fault clearing of all terminals and high-speed reclosing of the transmission terminals. Economics and environment dictate the use of high-frequency cable instead of microwaves when the distances between terminals are 5 miles or less. Examples are given of the compatibility and flexibility afforded by this method of extending relaying communications. The methods that are used to circumvent the problem of power station rise of ground potential and the protection of communication equipment and cable are also described. Termination facilities for coaxial and balanced-pair cable installations are included.