html{display:none} Transmission Protection | Schweitzer Engineering Laboratories

SEL transmission protection solutions provide complete primary and backup protection from all types of faults. Using these devices helps you avoid expensive equipment damage and failure while maintaining system performance and increasing availability.

Comparison Chart

Time-Domain Protection

Time-domain protection relays use a combination of traveling-wave and incremental-quantity protection technologies to achieve ultra-high-speed tripping.

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Transformer Protection

SEL devices protect valuable transformers in power transmission systems.

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Busbar Protection

Protect busbars and switchgear with high-speed differential fault detection, or expand your protection with features such as restricted earth fault, arc-flash, and overcurrent elements.

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Capacitor Bank Protection

Capacitor protection and controls increase power efficiency and reliability by improving the system’s power factor and voltage stability.

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Digital Secondary System Solutions

Time-Domain Link (TiDL) technology and SEL Sampled Values (SV) technology help protect and control substation primary equipment using digital devices in the secondary system that transmit data via fiber-optic cables.

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Remote I/O

Remote I/O modules transfer data from remote locations over fiber and expand the I/O of SEL relays, automation controllers, and other devices without modification to the control panel face.

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Configuration and Visualization Software

SEL software helps you optimize the configuration of your device and visualize power system events.

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Panels and Enclosures

Pre-engineered or custom panels and enclosures help keep costs low and increase system reliability when used for retrofit upgrades and new equipment installations.

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Transmission and Subtransmission Features

Distance Protection  
Line Current Differential              
Breaker Failure Protection ƒ ƒ ƒ ƒ     ƒ
Undervoltage Load Shedding ƒ ƒ ƒ ƒ ƒ   ƒ     ƒ
Series-Compensated Lines            
Subcycle Distance Elements        
21G Mho Ground Distance    
21G Quad Ground Distance        
21P Mho Phase Distance    
21P Quad Phase Distance         
TD21 Incremental-Quantity Distance (Phase and Ground)        
TD32 Incremental-Quantity Directional        
TW32 Traveling-Wave Directional        
TW87 Traveling-Wave Differential         
87L Line Current Differential              
25 Synchronism Check          
27/59 Under-/Overvoltage      
49 Thermal   ƒ ƒ              
50 (N,G) Overcurrent (Neutral, Ground)    
50P Phase Overcurrent    
50Q Negative-Sequence Overcurrent      
51 (N,G) Time-Overcurrent (Neutral, Ground)    
51P Phase Time-Overcurrent    
51Q Negative-Sequence Time-Overcurrent      
67 (N,G) Directional Overcurrent (Neutral, Ground)    
67P Phase Directional Overcurrent      
67Q Negative-Sequence Directional Overcurrent      
81 Under-/Overfrequency            
Programmable Analog Math                
Out-of-Step Block and Trip        
Load-Encroachment Supervision    
Single-Pole Trip      
Zone/Level Timers    
Pilot Protection Logic      
Instrumentation and Control
79 Automatic Reclosing   ƒ     ƒ
Number of Controlled Breakers  2 2 2 1 1 1 1 1 2 1
Fault Locating  
Single-Ended Traveling-Wave Fault Locating                
Double-Ended Traveling-Wave Fault Locating               
Adaptive Autoreclose Cancel Logic for Hybrid Lines               
Line Monitor                  
SELogic Control Equations    
Nonvolatile Latch Control Switches      
SELogic Remote Control Switches    
SELogic Local Control Switches      
Display Points        
Mirrored Bits Communications  
Substation Battery Monitor     
Breaker Wear Monitor        
Trip Coil Monitor ƒ   ƒ ƒ ƒ ƒ ƒ ƒ    
Event Records (Multicycle Data)
1 MHz Sampling Event Records                
Sequential Events Recorder
Instantaneous Metering  
DNP3 Level 2 Outstation
Parallel Redundancy Protocol (PRP)              
IEEE 1588 Precision Time Protocol Version 2 (PTPv2)        
IEC 61850-9-2 Sampled Values Technology         
Time-Domain Link (TiDL) Technology         
IEC 61850 Communications            
Built-in Event Playback Testing        
SEL Fast Time-Domain Values        
Miscellaneous Features
Accepts Delta Voltage Transformers                  
Connectorized (Quick Disconnect) Available          
Configurable Labels               
Custom Labels               

Standard Feature

Model Option

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