(August 25, 2005) -- The loss of a major western transmission line just as CA power use was
approaching its peak today forced the California Independent System Operator (ISO) to issue a Transmission Emergency notice for So. Cal, asking southland utilities -- including Southern California Edison which serves Long Beach -- to reduce demand on the system [our translation: cutting some customers].
As a result, parts of LB and some other southland cities were blacked out for a little over half an hour on Aug. 25. SCE cut power by about 800 megawatts (a megawatt is enough power for about 650 homes) as part of a rolling blackout (what it calls a "controlled outage") affecting some parts of LB.
The event began at 3:57 p.m. and power was restored at 4:35 p.m, SCE said. The exact geographic areas affected weren't immediately available.
However SCE has said exactly what areas may be next if something else triggers more "rolling blackouts" or "controlled outages". To find out if your home or business is in an area likely to be affected, read further.
SCE says the August 25 "rotating outages" were triggered "after the intertie, operated by the Los Angeles Department of Water and Power, tripped off line. After the loss of the intertie, SCE was directed to immediately reduce the demand for electricity in Southern California, necessitating a series of controlled rotating power outages within its service area to prevent a potential widespread disturbance to California's electric transmission grid," SCE said in a release.
"This was being accomplished by taking groups of circuits out of service on a rotating basis. The outages affected approximately 246,000 customers in small portions of several cities, among them Long Beach, Santa Barbara, Irvine, Chino Hills, Palm Desert, Torrance, and San Bernardino. Additionally, approximately 163,000 interruptible customers also were affected," SCE said.
CA ISO says the "Pacific DC Intertie, (PDCI) a 500-thousand volt transmission line that runs between Southern Oregon and Southern California suddenly and unexpectedly dropped out of service just before 4:00 P.M. today. The loss of more than 2,800 megawatts of power coming into Southern California, coupled with the area’s high demand required a reduction in system load to keep the grid in balance. Loads in southern California were running about 2,000 megawatts higher than anticipated due to temperatures that were up to 14 degrees higher than forecast.
No details are available yet about what caused the PDCI to trip off line, CA ISO said.
SCE says "rolling blackouts" or "controlled outages" generally last up to one hour for affected customers, but can be shorter or longer in duration, depending upon circumstances."
So, if something like this happens again, is your home or business in the next area likely to be affected? Check your SCE bill...because it lists your "rolling outage group."
As of Aug. 25 at 7:40 p.m., SCE said "if outages are called for, the next Rotating Outage Groups likely to be curtailed are:
A046, A047, A048, A049, M006, M007, M008, M009, R001, R002, R003, R004, S001, S002, S003, S004." [Caveat: If these areas are blacked out, the utility will add new areas as the next ones likely to be blacked out...so check SCE's web page below.]
The information is on the following SCE website page: SCE Rolling Outages Info.
(There are no community listings or maps for outage groups beginning with the letter "S"; if you're not sure what your Rotating Outage Group number is, you can find out using the page link above.)
During an emergency, SCE urges the public to:
- Exercise extreme caution, especially at intersections where traffic signals may not be functioning;
- Avoid using elevators anywhere during this Stage 3 Emergency;
- Do not call 911 due to a power interruption;
- Check on the medical needs of family and friends;
- Use flashlights, not candles, if you are without lights;
- Turn off all electrical equipment in use at the time of a service interruption, including sensitive electronic components;
- Leave one light bulb turned on to signal that power has been restored; and,
- If possible, monitor radio and television news stations to stay informed of developments and safety instructions.
CA's Independent System Operator says the Aug. 25 peak demand was 44650 megawatts...and its forecast peak demand was 41319. As of 8 p.m. on Aug. 25, CA ISO's forecast peak demand for Friday Aug. 26 is 41152 (subject to change.)
SCE says that with "power reserves still low," it encourages all consumers and businesses to reduce their power use at this time by keeping their air conditioning thermostats set no lower than 78 degrees, reducing office lighting, and using nonessential business equipment and home appliances (e.g., clothes washers/dryers, and dishwashers) in the morning or evening when demand for power is lower." It also offers other ways to cut power use:
- Close drapes and blinds to keep out direct sunlight during hot periods;
- Use electric fans instead of air conditioning if practical;
- Avoid using evaporative coolers or humidifiers at the same time an air conditioner is running;
- Operate swimming pool equipment during early morning and evening hours; and
limit the opening and reopening of refrigerators, which are major users of electricity in most homes.