Reliability Incident Reports

NERC, NPCC and the Market Rules all specify requirements for disturbance reporting to be met by their members and market participants. A system disturbance is an unplanned event that produces an abnormal system condition on the bulk electricity system. It may be associated with a fault and be characterized by the loss of power system stability, cascading outages of transmission circuits or abnormal ranges of frequency or voltage.

Reliability Incident Reports


• June 12, 2007 Events - 5% Voltage Reductions & Emergency Energy Purchases
  The IESO implemented Emergency Energy purchases and a 5 % voltage reduction on June 12, 2007. The need for the emergency control actions was due to higher than forecasted demand and the tripping of a 500 kV circuit, D501P. All equipment loading and voltages remained within acceptable emergency limits.



• Richview SC22 Incident - January 30, 2007
  This report documents the incident on January 30, 2007 in which a 3 phase fault occurred at the Richview Transformer Station resulting in the loss of approximately 1500MW of load in Ontario.



• Cherrywood Circuit Breaker Incident - December 12, 2005
  On December 12, 2005 a circuit breaker air fill valve that failed resulted in a stuck breaker and precipitated the incident described by this report.



• August 3rd and 4th, 2005: Energy Shortfall and Voltage Reductions
  This report describes the events leading up to and during the energy shortfalls on August 3rd and 4th, 2005.



• Milton Fault and Voltage Excursion May 27, 2005
  An investigation into the incident on May 27, 2005, when a 3 phase to ground fault led to the loss of approximately 2,300 MW of load in Ontario and voltage oscillations that were observed by neighbouring interconnected utilities.