Please direct to any previous site if this question has been ask before. What is the connection between telecommunications and the power grid? I have read that they are very interdependent but can they operate without each other? What makes them so interdependant?

-- Anonymous, November 13, 1998

Answers

It takes power to operate the telephone switches and voice/data transmission systems. Large central office switches and PBXs will have battery backup in the range of 4-8 hours and the COs will usually have backup diesel generation as well. Refueling and generator duty cycle issues discussed elswhere still apply.

Utilities have equipment spread over vast geographic areas. All these locations cannot be manned, therefore SCADA/EMS Systems are used to remotely manage these sites. To manage a remote location you have to be able to communicate with it. Various technologies are used to communicate with these sites: microwave radio, satellite radio, cellular modems, private fiber and leased telephone data circuits. Large utilities may have hundreds of circuits leased from multiple carriers(i.e. no way to test in advance) and will also have a mix of radio technologies as well.

SCADA/EMS systems provide for: remote problem determination and restoration, security(risk) evaluations of the transmission system, and economic dispatch of generating units.

When you lose communications it will take much longer to locate and restore failed equipment. Real-time security functions will not be available and generation will have to be switched to local frequency/voltage control. Economic operation will not be a priority at this time.

The percentage of leased circuits will determine the risk level of a given utility.

Jim

-- Anonymous, November 13, 1998