Operational Transmission Limits
Information pertaining to defined limits on New England External Interfaces - TTC, calculation methodology and other operating limit information.
External interface limit information that is updated on an hourly basis as well as on a daily basis. Information related to the current Operating Day is updated hourly, information posted beyond the current Operating Day is updated a minimum of once per day (by 11:00 a.m.) and when system topology changes are forecasted.
Single-source contingency in New England is a limit placed on generation and external interfaces in which the loss of a single piece of equipment could cause a loss of 1,200 megawatts or more. When favorable system conditions exist in the New York System Operator (NYISO) and PJM Interconnection (PJM) control areas, additional margin is granted on an hourly basis. The following page shows, in near real time, the additional margin available for authorization in the NYISO and PJM control areas, how much margin has been granted by those control areas, and the net schedule on an affected external interface (Phase II).