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Loss Penalty Factors (SE-40)

Loss penalty factors are intended to represent the transmission losses associated with each resource. In Ontario, the term resource refers to all generators and loads as well as all intertie connections. Transmission losses are a natural occurrence when moving power from one point to another and are the result of heating, energization, magnetization, size and type of cable. Loss penalty factors are the incremental transmission losses based on the location of the resource with respect to a reference bus and the flow of power on the grid.

Static loss penalty factors were employed prior to market opening as a replacement for the dynamic module. These static loss factors have not been updated since market opening.

Loss factors are currently being recalculated based on the current grid configuration and will be distributed to market participants for discussion. An analysis will be undertaken to investigate future options to adjusting the loss factors.

For more information, see the Stakeholder Plan below

Stakeholder Engagement Plan (Revised, March 24, 2010)
Stakeholder Engagement Plan (Revised, January 26, 2010)
Stakeholder Engagement Plan (Revised, November 5, 2009)

Previous versions of the Stakeholder Engagement Plan are available upon request.

Loss Penalty Factors (Updated, January 19, 2011)
Proposed Loss Factors (Updated, December 23, 2010)

For more information on this stakeholder initiative or to participate in the next meeting, email stakeholder.engagement@ieso.ca.

 Schedule of Activities


Supporting Material

​December 2010

​Consultation closed

December 23, 2010

Communication on Loss Penalty Factors to be implemented January 19

August 19, 2010


  • Proposed Loss Factors (updated September 1)

March 17, 2010

Due date for written feedback on penalty loss factors
Stakeholder Feedback

February 25, 2010

Communication on Loss Penalty Factors to be implemented March 17.

February 4, 2010

Deadline for stakeholder feedback on recommendation
Stakeholder Feedback

January 28, 2010

Stakeholder Engagement Plan updated

January 21, 2010
1:00 -2:00 p.m.

Webcast meeting with stakeholders to discuss options moving forward on how to effectively manage changing loss penalty factors

November 5, 2009

Stakeholder Engagement Plan updated

June 2, 2009

Update on initiative provided at June 2 Dispatchable Load Working Group meeting

September 17, 2008

Stakeholder Engagement Plan updated

April 2008

Additional penalty factors calculated based on snapshots from prior year

December 13, 2007

Stakeholder Engagement Plan Updated

October 10, 2007

Implementation of changes to loss factors

September 12, 2007

Deadline for stakeholder feedback on revised penalty factors

August 28, 2007

Posting of revised penalty factors on the IESO website

May 2007

Post IESO response to stakeholder feedback and advise individual participants on changes to loss factors
Stakeholder Feedback

April 30, 2007
Minutes (Draft)

Conference call to discuss re-calculated loss factors and options for changing loss factors

April 24, 2007

Deadline for stakeholder feedback on plan and discussion paper
Stakeholder Feedback

April 23, 2007

Distribute re-calculated loss factors to dispatchable generators, dispatchable loads importers and exporters

April 10, 2007

Post stakeholder plan and loss penalty factor paper for comment