Protective Relay and Metering. The following provides the basic relay and protection philosophy and requirements. The final design will be subject to the approval of the Connecting Transmission Owner and will conform to the Connecting Transmission Owner protection requirements.
Protective Relay and Metering. The following provides the basic relay and protection philosophy and requirements. The final design will be subject to the approval of the Connecting Transmission Owner and will conform to the Connecting Transmission Owner protection requirements. • Primary Line Protection (WPN-1 and PND-1) - Distance relaying protection is the primary protective function and is provided via a Siemens 7SA522 microprocessor based relay. The relay will trip the line breaker(s) and initiate primary breaker failure protection. • Secondary Line Protection (WPN-1 and PND-1) - A General Electric L90 current differential with distance backup protective relay will be used for secondary line protection. Instantaneous/time over-current function will provide additional back-up SERVICE AGREEMENT NO. 1774 protection. The relay will trip the line breakers and initiate secondary breaker failure protection. • Breaker Failure - When initiated, a Siemens 7SJ61 breaker failure relay will issue a retrip and begin a timer. If the circuit breaker fails to open within a specified period, the breaker failure relay will energize its associated lockout relay, which will trip and block closure of the adjacent breaker(s) and send direct transfer trip to the other end. • Transfer Trip - Two bi-directional direct transfer trip (DTT) systems will be utilized for the Xxxxxx-Xxxxxxx WPN-1 and Xxxxxxx-Xxxxx PND-1 lines. The DTTs will be sent/received via power line carrier and microwave for exceptional reliability. A transfer trip will be sent to Xxxxxxx in the event of a breaker failure to trip at Xxxxxx substation and vice versa. Similarly DTT signals may be transmitted from Xxxxx to the Xxxxxxx Substation and from Xxxxxxx Station to Xxxxx. • Synch Check Relay - A GE MLJ100 synch relay will compare voltages across circuit breakers to prevent the breaker from closing in out of phase. • Breaker Auto Reclosing - A Xxxxxx BE1-79M multiple shot reclosing relay for each breaker will be utilized in the Synch Check relay to provide auto reclosing of the breakers. • Remote Control - The Connecting Transmission Owner will have the ability to remotely open the Xxxxxxx Substation line circuit breakers and motorized line disconnect switches from the Connecting Transmission Owner’s control center.
