SPS Mis-operation – DRAFT Proposal for ERCOT

procedures

Discussion of SPS Mis-Operation• SPS Mis-operation is not explicitly defined in the ERCOT

Protocols or Operating Guides, but is described as the operation of an SPS when the conditions of the SPS have not been met, or the lack of operation of an SPS when the conditions have been met. The ERCOT Operating Guides section 7.2.3.2 does list several events that could describe an SPS mis-operation. These events are listed below:

• Failure to Trip – Any failure of a protective relay system to initiate a trip to the appropriate terminal when a fault is within the intended zone of protection of the device.

• Slow Trip – A correct operation of a protective relay system for a fault in the intended zone of protection where the relay system initiates tripping slower than the system design intends.

• Unnecessary Trip During a Fault – Any relay initiated operation of a circuit breaker during a fault when the fault is outside the intended zone of protection.

SPS Mis-operation - continued• Employee action that directly initiates a trip is not

included in this category. It is the intent of this reporting process to identify mis-operations of the relay system as it interrelates with the electrical system, not as it interrelates to personnel involved with the relay system. With this in mind, if an individual directly initiates an operation, it is not counted as a mis-operation (i.e., unintentional operation during tests). On the other hand, if a technician leaves trip test switches or cut-off switches in an inappropriate position and a system fault or condition causes a mis-operation, this would be counted as a relay system mis-operation

• Failure to Reclose – Any failure of a protective relay system to automatically reclose following a fault if that is the design intent.

Responsibilities for Investigation• When an SPS mis-operation occurs, the TO shall

provide to ERCOT the same written documentation outlined by the Operating Guides, stating what the cause of the mis-operation was and outline what steps have been made to ensure that this same misoperation will not happen in the future within 5 business days (ERCOT Operating Guides, section 7.2.3.3). Again, ERCOT System Operations shall make the final determination as to whether or not the SPS mis-operated.

• ERCOT Operations shall make the final determination whether or not that SPS had mis-operated, following the process outlined below:

Investigation- continued• ERCOT System Operations and Transmission Services shall

independently review the report filed by the TO.• ERCOT System Operations and Transmission Services shall

meet and discuss the results of their review. Any remaining questions or comments remaining shall be sent to the TO.

• ERCOT System Operations and Transmission Services shall review the replies from the TO, if any, and decide whether or not the SPS has mis-operated.

• The final decision shall then be sent to the Director of System Operations and the Director of Transmission Services for final approval of the decision, which will then be sent out to the TO and to all relevant working groups, task forces, and subcommittees.

• Should an SPS mis-operate 2 times or more within the 5 year period of the SPS, ERCOT may request that the SPS be disabled until further review of the SPS and its mis-operations can be made.