In order to provide a continuous path for the microwave installation between the Seward ,generating plant and the Johnstown plant of the Pennsylvania Electric Company's system, a reflector installation was used as line-of-sight was not available. This article describes the microwave channel and the terminal equipment.C O M M U N I CAT IO N CHANNELS, for transmitting the various types of intelligence necessary for operation of a power system, are becoming increasingly important to the utility industry because of the trend toward centralized system control. Pilot-wire and powerline carrier channels are already widely used to accommodate the many items of information necessary for efficient system operation. Microwave channels are the most recent addition to the means of communication available for this purpose.A microwave channel! is a beamed high-frequency radio communication medium which can be used to transmit from point to point the intelligence required in the normal operation of a power system. Relaying, telemetering, supervisory control, and voice communication are some of the functions which can use such a channel. The large number of items of information which can be transmitted simultaneously over a microwave channel makes it particularly valuable at locations where communication traffic is heavy.It is the purpose of this article to describe an experimental installation of a microwave channel and terminal equipment which accommodates simultaneously three voice conversations, two different types of protective relaying, two telemetered quantities, and supervisory control of eight points. A feature of considerable interest on this installation is the use of a reflector to provide a continuous path for the microwave beam between the terminal stations, where line-of-sight was not available. The use of the reflector eliminated the need for 2 1 / 4 miles of cable originally planned to connect one of the terminal stations to a point where line-of-sight to the other station was possible.The installation is on the system of the Pennsylvania Electric Company and ties together the main generating plant at Seward and the operating headquarters at Johnstown, Pa. A joint test program has been carried out during the past year by the Pennsylvania Electric Company and the Westinghouse Electric Corporation.The Seward generating plant is the terminus for powerline carrier communications, telemetering, and supervisory control equipment for the entire power system. The efficient operation of the system depends on adequate and reliable communication facilities between the system operator in Johnstown, approximately 12 miles distant, and the Seward plant. The use of wire lines in the past has not been satisfactory because of outages and inferior service caused by extreme conditions, such as landslides, icing, automobile accidents, and gunshots.The problem, therefore, was to prove that microwave and audio multiplex equipment provide a reliable channel which is suitable for voice communications, telemetering, supervisory control, ...
