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

Distance Protection Relays

These phase and ground distance and directional protection relays can be applied for single- and three-pole tripping schemes, compensated lines, or uncompensated 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    
Undervoltage Load Shedding 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          
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      
Number of Controlled Breakers  2 2 2 1 1 1 2
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    
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
Connectorized (Quick Disconnect) Available        
Configurable Labels          
Custom Labels           

Standard Feature

Model Option

ƒ This function may be created using settings