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-411L Advanced Line Differential Protection, Automation, and Control System
Apply the SEL-411L Relay for complete protection and control of any transmission line. The SEL-411L provides differential protection with both phase and sequence based operating elements for sensitivity and high-speed operation.
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- 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 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 Transmission Protection System
Apply the SEL-311C Relay for complete protection, monitoring, and control of transmission lines.
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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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