Special Protection Systems
Special Protections Systems are presently defined as: "An automatic protection system designed to detect abnormal or predetermined system conditions, and take corrective actions other than and/or in addition to the isolation of faulted components to maintain system reliability. Such action may include changes in demand, generation (MW and Mvar), or system configuration to maintain system stability, acceptable voltage, or power flows. An SPS does not include (a) underfrequency or undervoltage load shedding or (b) fault conditions that must be isolated or (c) out-of-step relaying (not designed as an integral part of an SPS). Also called Remedial Action Scheme."

Standards Related to SPSs
PRC-012 is a Fill-in-the-Blank Standard that requires an SPS owner to submit detailed information to the Regional Entity for review of the SPS.  The MRO has an SPS Working Group made up of Planning Engineers and System Protection engineers. The SPS owner presents the SPS to this working group and MRO staff. Once the SPS is thoroughly reviewed and judged to meet the requirements of PRC-012, it is added to the MRO database per PRC-013.  The same review process for PRC-012 occurs if the SPS is existing and is undergoing functional changes.

PRC-014 requires a 5 year cyclical review of all SPSs by the MRO.  Updated studies are submitted to the MRO and care is taken to assure that coordination of SPSs occurs during this 5 year review.

PRC-015, PRC-016 and PRC-017 are SPS-related mandatory Standards that apply to the SPS owner.

A drafting team has been formed to combine/reduce these six SPS-related Standards into 1-2 mandatory Standards.  Work has just started on this.

An SPS owner submits a new or modified SPS to MRO Staff according to the timing requirements found in the MRO Procedure for PRC-012 and PRC-014​

For 5 year cyclical review of SPSs (PRC-014), MRO initiates a request to the SPS owner per the timing requirements.  MRO typically will request that SPSs within a certain area be reviewed at the same time to address any coordination issues that may be of concern.

MRO's Role
MRO's role is to review the SPS to verify that it meets the requirements in PRC-012.  MRO as well as other regions typically use a team of stakeholders to perform this review.  In the future, the role of SPS review will be assigned to the Planning Coordinators and Reliability Coordinators.

Need More Information?
If you have a question regarding this data request for MRO please contact mrorapa@mro.net. ​