Project Profiles: Protection & Control
Transmission Relay Coordination Study
NSTAR, a major electric utility in Massachusetts, contracted PLM to do a thorough relay coordination study for an entire 345 kV, 230 kV, and 115 kV looped transmission system. The study involved a review of directional-distance phase relays, directional-distance ground relays, and phase and ground overcurrent relays. The existing relay settings were modeled in ASPEN, a short-circuit computer program, and the settings were analyzed both on a circuit basis and also for relay-to-relay coordination between primary and backup systems.
115kV Relay Upgrade
The Braintree Electric Light Department hired PLM to upgrade their 115kV protection system. This included replacement of electro-mechanical relays with microprocessor-based relays, providing for redundant battery systems, replacing 115 kV oil circuit breakers with SF6 circuit breakers, adding breaker failure protection and adding high-speed Permissive Overreaching Transfer Trip and current differential line protection via a multiplexed fiber optic communication system.
SCADA System
Back to Top
The Norwood Municipal Light Department retained PLM to assist in the procurement of a new SCADA system to augment an existing load management system. The SCADA system provides monitoring and control of two substations and two switching stations back to redundant master computers.
Contact UsCopyright 2005 by PLMDesigned by