Transmission Protection
SEL revolutionized the protection industry by building the first microprocessor-based protective relays. These relays integrated, economized, and simplified the art of transmission line protection while introducing two powerful tools: fault locating and event reporting.
- SEL-421 Protection, Automation, and Control System
Protect Transmission Lines With High-Speed Distance and Directional Functions.
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- SEL-311L Line Current Differential Protection and Automation System
Use the SEL-311L Line Current Differential Relay with Integral Four Zone Distance Backup for Easy-to-Apply High-Speed Line Protection.
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- SEL-387L Line Current Differential Relay
Use SEL-387L Line Current Differential Relays for economical, easy-to-apply line protection.
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- SEL-311C Advanced Distance Relay With Recloser
Apply the SEL-311C Relay for complete three-pole distance protection, monitoring, and control of transmission lines.
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- SEL-311B Distance Relay With Recloser
Economical step distance protection using the SEL-311B Relay with four-shot reclosing and synchronism check.
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- SEL-311A Phase and Ground Distance Relay
Implement subtransmission, or backup distance protection at a very low cost with the SEL-311A Relay.
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- SEL-321 Phase and Ground Distance Relay
The SEL-321 Relay delivers outstanding EHV protection, performance, and features—at a price practical for all voltage levels and with the features you need for system integration.
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- SEL-321-5 Phase and Ground Distance Relay
Select the SEL-321-5 for 50 Hz applications requiring enhanced single-pole tripping, phase and ground distance, directional overcurrent, and negative-sequence protection.
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- SEL-279H Reclosing Relay
Use the SEL-279H as a reclosing relay for one or two breakers including synchronism checking and voltage checking for single-pole or three-pole trip applications.
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