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.

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    
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   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      
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
Accepts Delta Voltage Transformers            
Connectorized (Quick Disconnect) Available      
Configurable Labels          
Custom Labels         

Standard Feature

Model Option

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