When updates to ambient adjusted ratings (to comply with FERC Order 881) require a certification review

Nearly four years ago, the Federal Energy Regulatory Commission (FERC) issued Order 881, requiring all transmission providers to use ambient adjusted ratings (AARs) as the basis for evaluating near-term transmission service to increase the accuracy of near-term line ratings. As the July 12, 2025, deadline for this shift approaches, here’s what to know about when updates to AARs may require a certification review.

In all cases, ReliabilityFirst (RF) recommends that entities keep documentation relating to their implementation of AARs and continue to regularly meet with their Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) to understand expectations and timelines. For more information on certifications in general, click here.

When no certification activity is required for AAR implementation

Entities do not need to submit a certification application/questionnaire to RF for tweaks or adjustments to their Energy Management Systems (EMS) that are specific to the implementation of AARs per FERC Order 881.

The purpose of certifications is to allow Regional Entities (like RF) to work with entities to ensure they are ready and able to perform requirements as a newly registered Transmission Operator (TOP), Reliability Coordinator (RC), and/or Balancing Authority (BA), and in some cases when entities make changes to their footprint, control centers, or EMS. However, they are generally not designed to prepare entities to comply with NERC Standards, or in this case, a FERC Order.

When certification activity may be needed during AAR implementation

When your organization’s integration of AARs involves additional updates that go beyond just minor updates required for AAR implementation, such as instances that include a complete replacement of your EMS or SCADA system or a major system upgrade (e.g. going from EMS Version 1.1 to version 2.3 with all new functionality and significantly different operator screens/situational awareness, virtualization changes/implementation, installation of new hardware, etc.), a certification review (or lesser certification activity) may be necessary. In these instances, please complete the RF Certification Notification and Preliminary Questionnaire.

If you have questions, please contact RF’s Entity Engagement department via the drop down on our Contact Us page. And as always, if you need assistance, you can fill out an Assist Visit request form.

 

Further reading:

PJM Facilitating Dynamic Line Rating Implementation – by PJM

MISO FERC Order 881 Update RSC-2018-54A/B – by MISO

Understanding the Requirements of FERC Order 881 – by MRO

Managing Transmission Line Ratings FERC Order 881 – by New York ISO

FERC Order No. 881 Compliance – by ISO New England