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.

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.


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