Mon, Feb 03, 2020 05:37 PM

M-A020320-01 Planned Transmission Outage Restrictions for Summer 2020

NOTICE DATE: February 3, 2020

NOTICE TYPE: M-A020320-01 Operations

SHORT DESCRIPTION: Planned Transmission Outage Restrictions for Summer 2020


DAYS AFFECTED: May 15, 2020 through September 15, 2020

LONG DESCRIPTION:  In an effort to manage Planned Transmission Outages that might limit generation availability during high load conditions, ERCOT is implementing a set of restrictions on Planned Transmission Outages for summer 2020.  These restrictions are the same as the restrictions that were in effect for summer 2019.   ERCOT will apply these summer outage restrictions, in addition to normal outage coordination guidelines, in its standard processes for evaluating Planned Transmission Outages.

The summer outage restrictions apply to Outages that are to be in effect from May 15 through September 15, 2020 (the summer restriction window).  For Outages that begin before May 15 or extend after September 15, 2020, the restrictions apply to the duration of the Outage that extends into the summer restriction window.  The restrictions apply to Planned Transmission Outages of existing equipment; the restrictions do not apply to Outages of new facilities when those Outages are necessary to synchronize the future equipment in the ERCOT model with the actual initial energization date of the new facilities (Protocols Section 3.3.1 ERCOT Approval of New or Relocated Facilities).

General Restrictions:

345kV and 138kV   

  • No Outages during Hour Ending (HE) 1300 through HE 2000.
  • No 345kV bus Outages.
  • No 138kV bus Outages that alter system topology (pre- or post-contingency).  Outages on double breaker or breaker-and-a-half buses may be allowed with a 4-hour restoration.  Transmission Service Providers (TSPs) are required to ensure proper interim contingency definitions are included in the Network Operations Model prior to the Outage occurring so that ERCOT systems can properly assess system conditions during the bus Outage.
  • No 345kV transformer Outages.


  • No Outages during HE 1300 through HE 2000 if the Outage would affect generation dispatch.

Some exceptions to the General Restrictions listed above MAY BE allowed, on a case by case basis, as listed in the Potential Exceptions below.  In order for an Outage to be considered under the Potential Exceptions listed below, the TSP requesting the Outage should provide the information necessary for ERCOT to consider the applicability of the Potential Exception at the time the Outage is submitted by including the exception request and justification in the Comment field for that Outage in the Outage Scheduler.

Potential Exceptions:

  • Outages on radial transmission that does not connect available generation.
  • Outages on local load-serving networks that are essentially radial in nature and do not contain available generation.
  • Daily full-day Outages on specific Competitive Renewable Energy Zone (CREZ) transmission lines under low wind conditions.
  • Outages which pose a greater transmission system reliability risk through the summer if NOT completed.
  • Outages where the Outage itself would reduce congestion; or,
  • Outages where the reliability need for the Outage, including the interconnection of new generating capacity, exceeds the potential risk that the Outage will restrict generation.

In the event of a second occurrence of an Outage approved under these exceptions being unavoidably extended beyond HE 1300 for a particular TSP, the approval of any of that TSP’s subsequent Outages that have not already begun will be withdrawn, and future Outages will not be approved, unless the Outage has a 4 hour or less restoration time.  

CONTACT: If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at ClientServices@ercot.com.

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