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May 2, 2002
JEA COMPLETES INITIAL REVIEW OF MONDAY'S POWER OUTAGE
As a result of the events of Monday, April 29, JEA's electric system suffered no serious damage and remains in excellent condition. Of the thousands of devices that operated on April 29, only one, to our knowledge, is broken. This one device is a circuit breaker at the Kennedy Generating Station. A complete backup circuit breaker at the Kennedy Generating Station is now in service while the damaged circuit breaker is being replaced. We expect to continue to serve our electric customers with the same reliability as we provided prior to April 29.
JEA's electric utility is designed and maintained to high standards. Our utility protection and recovery systems performed very well in response to the extraordinary events of April 29. Such major events occur at American electric utilities approximately thirty (30) times annually. This is the first such event to occur at JEA for twenty-five (25) years.
Whenever events such as this occur in the United States, well-established national and regional procedures are used to rigorously analyze the event through extensive peer and regulatory review. (Sample analyses concerning events at other electric utilities are available upon request.) JEA has already begun its analysis and expects to be completed within sixty (60) days. We look forward to sharing the final report with anyone interested in the details.
Based on initial review, the sequence of relevant events appears to be:
- 3:50:56 p.m. - A lightning arrestor on a 138,000-volt transmission line in west Jacksonville failed. This event triggered automatic protective equipment to safely remove this line from service, as designed. Simultaneously, a protective relay operated on one of the two 230,000-volt transmission lines connecting the Normandy Substation to the Brandy Branch Substation removing this line from service. This placed the entire power flow from Brandy Branch Substation on the second of the two lines. Each of the two lines is designed to carry this amount of power. (Thousands of lightning arrestors and protective relays on JEA's system continuously protect customers from outages.)
- 3:55:52 p.m. - The second 230,000-volt Brandy Branch line was automatically removed from service. Since all transmission lines sag when loaded, the second Brandy Branch line sagged more with the increased load causing it to contact trees below. For safety reasons, protective relays removed the line from service, as designed. This resulted in approximately 800 megawatts (MWs) that had been flowing over this line to begin flowing over other transmission lines in north Florida. Due to the high flows on these other transmission lines, the transmission voltage in the Jacksonville area became unstable.
- 4:22:09 p.m. - To protect JEA and customer equipment from this unstable voltage, automatic protective relays, as designed, began safely disconnecting JEA interconnections with other utilities and JEA generation at the Northside Generating Station, the Kennedy Generating Station, and the St. Johns River Power Park. A 138,000-volt circuit breaker caught fire as it operated to disconnect the Kennedy Generating Station. At the same time, customers began to be automatically and safely disconnected. By 4:25:00 p.m. 98 percent of JEA's customers had been disconnected.
- 4:27 p.m. - JEA reestablished the transmission interconnections with other utilities and began starting quick-response generating units. Customers were restored as quickly as the rising generation would allow.
- 6:22:26 p.m. - JEA had restored approximately 60% of our customers when both Brandy Branch lines were again automatically removed from service causing a repeat of customer interruptions. Analysis continues to determine the reason for this automatic action.
- 6:25 p.m. - 1:30 a.m. - JEA continued restoration procedures resulting in essentially all customers being restored by 1:30 a.m. Only a small number of customers remained out of service in locations that required JEA personnel on-site to restore service.
Individual events like a lightning arrestor failure, a relay malfunction, or electric lines contacting trees happen at all electric utilities. JEA's system is designed to be strong enough to withstand such individual events without affecting any electric customers. It is very unusual for several such events to occur in a brief period of time. During high electric demand, no electric utility, including JEA, can withstand such a combination of events without affecting customer service.
JEA's systems and procedures are designed to rapidly and safely restore customer electric service after such unusual events. These systems and procedures worked as designed. JEA regularly deploys on its system more reliable devices and technologies as they become commercially available. JEA's customers can expect this practice to continue reducing the possibility of such an event in the future.
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