The SEL Wireless Protection System enhances your distribution protection by enabling relays to block reclosing on underground faults, enabling fast bus tripping, or coordinating high-density recloser trip blocking. The system’s components include the SEL-FT50 Fault Transmitter, the new SEL-RP50 Fault Repeater, and the SEL-FR12 Fault Receiver. The SEL-RP50 supports the system by addressing communication challenges posed by large obstructions, such as buildings or trees, so it’s easy to transmit in any environment.
The SEL-FT50 Fault Transmitter weighs only 2 lb and is entirely line-powered, so installation is as simple as pairing it with an SEL-FR12 Fault Receiver in a nearby cabinet and then using a hot stick to clamp the unit onto the line. Each receiver can pair with up to 12 transmitters—with the option of placing multiple SEL-RP50 Fault Repeaters in between to send signals around obstructions back to the receiver—so your communication capabilities can adapt to whatever the local environment may be.
Distribution substation protection schemes typically aren’t able to distinguish between underground and overhead faults. Traditionally, utilities have had to choose between the possibility of undesired reclosing into an underground fault or blocking reclosing for a close-in overhead fault when a high-current lockout is used. By installing the SEL-FT50 at the riser pole, the relay can receive fault status information before the first trip and know whether the fault is overhead or underground. Reclosing then operates normally for overhead faults but is selectively blocked for permanent underground faults, preserving your equipment while also increasing service reliability.
A higher density of protective devices on distribution networks can help improve reliability metrics by reducing the number of utility customers affected by a fault within each isolation zone. However, traditional relaying coordination methods become increasingly difficult to implement as the total number of devices goes up. The SEL Wireless Protection System helps maintain selectivity and provide high-speed trip blocking for high-density recloser installations, allowing for consistent settings across devices and extending trip blocking capabilities to selected lateral fuses. For scenarios or environments that present communication challenges, the SEL-RP50 can forward the fault signal around local obstructions to ensure uninterrupted distribution protection.
Fast bus tripping schemes can provide a cost-effective solution for substation bus protection on radial systems. In some cases, however, communication between relays may not be feasible due to distance or cost. SEL Wireless Protection System devices are easy to install on substation feeders and provide high-speed wireless communication, allowing your system to quickly and correctly differentiate between feeder faults and bus faults.