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

SEL transmission line protection relays provide subcycle line differential and multizone distance protection for a secure, reliable, and high-speed solution. Their fault-locating capabilities allow you to efficiently dispatch line crews to quickly isolate line problems and restore service faster.

Comparison Chart

Differential Protection Relays

The sensitive differential elements in these protective relays provide subcycle operating times and can be applied on multiterminal lines.

Ultra-High-Speed Protection Relays

These ultra-high-speed transmission line relays built with the time-domain technology of traveling waves and incremental quantities are designed for speed, security, and ease of use.

System Components

Combining these components with line protection relays expands their functionality and simplifies testing.

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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