As electric utility operators, investigators, and officials review the sequence of events leading up to the largest blackout in U.S. history, among the tools at their disposal are power quality and multifunctional event recorders from Ametek Power Instruments.

These instruments with up to 1/1000th of a second accuracy are able to indicate how a power problem cascades through the electric power system. Ametek Power Instruments captured data documenting the initial power voltage drop and subsequent blackout that occurred on August 14 on the power monitoring and analysis instruments at its Rochester, NY, manufacturing facility. (Each phase of the August 14th blackout was captured by the P & QR 128 power quality recorder, pictured, from Ametek Power Instruments.)

The data, which is typical of information available to electric utilities at power plants and substations throughout the interconnected power grid, allows operators and others to identify the source of problems and take action to prevent them from recurring. Additionally, a Sequence of Events Recorder manufactured by Ametek's Rochester Instruments unit helped to pinpoint the cause of the previous "Great Northeast Blackout" in 1965.

On August 14, Fault and Power Quality Recorders at Ametek's Rochester facility indicated an initial power voltage drop of 10% occurring over an 870-millisecond time window. The voltage then recovered briefly as automatic protection systems attempted to maintain normal voltage. However, after recovering for 270-milliseconds, a second, more severe voltage drop of 22% occurred for 540 milliseconds. That voltage and associated frequency oscillations are indicative of the massive power swings that ultimately may cause the cascading outages that resulted in the blackout. (Data indicated by the red waveform recorded by Ametek Power Instruments TR2000 Multifunction Recorder clearly shows frequency oscillation that typically occurs during a sudden loss of a power plant or transmission line.)

The instruments at Ametek's Rochester plant captured the local blackout at approximately 8.2 seconds following the initial voltage problem. Power at the Rochester location was restored at 23:31:23.850, or 7 hours and 10 minutes later.

Ametek Power Instruments offers an extensive line of state-of-the art power quality and monitoring instruments.