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

Bus protection products and systems provide complete primary and backup protection for all types of bus and switchgear arrangements. They are suited for use in utility-, industrial-, and commercial-scale power systems.

Comparison Chart

System Components

Combining these components with bus protection relays expands their functionality.

Bus Protection Features

Breaker Failure Protection ƒ ƒ
Bus Differential ƒ
Transformer and Machine Current Differential      
High-Impedance Bus Differential      
Low-Impedance Bus Differential    
Three-Phase Current Inputs 4 7/
21 ‡
5 Com-
Three-Phase Voltage Inputs   1 2    3
27/59 Under-/Overvoltage    
46 Current Unbalance   ƒ    
47 Voltage Unbalance     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  
87 Current Differential    
87Z High-Impedance Differential      
Single-Pole Trip/Close        
Three-Phase Differential Bus Zones 1 2/
6 ‡
1 1  1
Check Zones   3      
Instrumentation and Control 
79 Automatic Reclosing   ƒ ƒ    
Dynamic Zone Selection        
SELogic Control Equations
Nonvolatile Latch Control Switches  
SELogic Remote/Local Control Switches
Display Points
Multiple Settings Groups  
Substation Battery Monitor    
Breaker Wear Monitor      
Event Report (Multicycle Data)
Sequential Events Recorder
Instantaneous Meter
Demand Meter  
Through-Fault Monitor      
IEEE C37.118 Synchrophasors        
Synchrophasor Real-Time Control        
IEC 61850    
Built-In Web Server    
Simple Network Time Protocol (SNTP)    
Rapid Spanning Tree Protocol (RSTP)    
Mirrored Bits Communications    
Parallel Redundancy Protocol (PRP)    
IEEE 1588 Precision Time Protocol Verion 2 (PTPv2)    
Time-Domain Link (TIDL) Technology     
Miscellaneous Features 
Connectorized (Quick Disconnect) Available    

Standard Feature

Model Option

ƒ This function may be created using settings

1/2/3 Relay Application