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2010-01-07

Rolling blackouts on tap for Medina Lake?

By Carol L. Smith

According to a recent letter from Brian D. Bartos, engineering manager for the Bandera Electric Cooperative (BEC), mailed to the residents of Medina Lake on Dec. 18, rolling black outs are possible for the Medina Lake.

Be prepared
New transmission lines are being installed from the Medina Lake substation, located just north of the intersection of FM 1283 and Park Road 37, along FM 1283 into Medina County, continuing south and east to near the intersection of Red Wing Road.

Running from the Pipe Creek substation, the Medina Lake substation is currently serviced by a single radial transmission line that was built in the 1960s and rated for 29 megawatts. If this radial line should fail, for whatever reason, all of the electrical service to Medina Lake would be interrupted.

In the letter, during times of extremely low temperatures, which Bartos defined as “below 25 degrees,” residents are urged to “turn off all unnecessary lights, turn your thermostat down a few degrees and unplug all appliances that are not in use.”

The impetus for the letter was a cold weather event on Dec. 5 in which the BEC experienced loads on the radial line to the Medina Lake substation of nearly 26 watts, which caused BEC administrators to become “very concerned about the potential for overloading this line.”

If the overloading happens again, due to the existing distribution system constraints, few options can keep the electrical service from being interrupted to the entire Medina Lake area. Planned load shedding - aka “rolling blackouts” - would be the last option available to keep from overloading the radial line and losing service to all the BEC customers serviced by the Medina Lake substation.

In a planned load shedding event, parts of the system are turned off for periods of 20 to 30 minutes, then turned back on, allowing other areas to be turned off. This sequence would be repeated as long as the overload event continues. According to Bartos, this action is only taken as a final, precautionary measure to prevent an even larger, more widespread outage or failure of equipment.

“I have only had to order load shed three times in my 26 year career,” stated Bartos in an email communication, “ however rare, we do constantly prepare for these events and hope they never occur.”

BEC may, under extreme circumstances, by ordered to load shed by the Electric Reliability Council of Texas (ERCOT) for events which may place the statewide power grid in significant jeopardy.

New, improved electrical service
Lines currently under construction are jointly owned by the Lower Colorado River Authority (LCRA) headquartered in Austin and City Public Service (CPS) headquartered in San Antonio. Once completed, the new lines will be rated for 220 megawatts and the BEC will perform the necessary improvements to the Medina Lake substation, including changing the power transformer. This work is planned to begin in February and end in March.

The BEC also plans to rebuild an old transmission line from Pipe Creek to Medina Lake in order to match the voltage and ratings of the new LCRA-CPS line. This improved transmission line will complete a new “looped” service to the Medina Lake substation that will significantly improve the electric reliability.

In a looped system, one side or the other can be out of service and the substation remains energized, with the current radial line, when the line fails the substation fails. Planned since 2005, this part of the project should be completed by June 2010.

As of press time, repeated attempts to contact the BEC or Bartos were unsuccessful, leaving a question regarding the service area of the Medina Lake substation unanswered.

For more information on how to conserve energy, visit www.banderaelectric.com and go to the Energy Use menu and then to Energy Tips. Call 830-796-3741 or 866-226-3372 to contact BEC personnel by phone.