City Light upgrades dams’ communication systems

City Light has just improved its communications system with its dams and generation facilities on the Skagit and Cedar rivers, to make them more reliable and flexible.

Workers with the contractor Aviat replaced City Light’s three-decade old microwave equipment at seven sites. They replaced antennas, waveguides, transmitters and other analog equipment, and installed new, state-of-the-art digital gear.

The older system served the utility well, but it has lived much longer than intended, and had become noisy and unreliable. The new digital gear is more robust, more efficient, and gives the utility a much wider “pipe” to transmit data between our Control Center and our remote generating facilities. It helps ensure that City Light will continue to produce affordable power and maintain control of river flows despite bad weather, an earthquake or some other unplanned event.

The microwave system is one of the several systems City Light uses to communicate with its remote sites. We also rely on fiber-optic lines and two-way radios.

Microwave communications systems work by sending a narrow, focused beam of energy between two sites that are aimed at each other. Some of our sites, such as the Bothell Substation communications tower, are in urban areas. Some of the others are in remote mountain tops, accessible by helicopter or off-road vehicles.

Workers also took the time to upgrade infrastructure at those sites, such as installing new grounding systems and dehydrators, and trimming vegetation to clear the way for signals. The Cedar Falls site even got a new 50-foot tower that will make that site more reliable, since it is taller than the vegetation around it.

The new system and upgrades were designed and planned by Senior Communications Engineer Janice Rios, with supervision by Lena Tat.