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SEL-551/SEL-551C and SEL-851 Comparison

Standard Feature
Model Option
Common features are not listed in this comparison. For more information, visit the product pages.

Display/Front Panel
Graphical LCD Display  
Local/Remote Control 
Trip/Close Breaker Control 
8 Programable LEDs 
USB-C Communications Port 
CT/PT Inputs
1 A/5 A Software-Selectable Current Inputs  
3 Voltage Inputs: VA, VB, VC 
Breaker Failure Protectionƒ
Underfrequency Load Shedding 
Undervoltage Load Shedding  
Loss-of-Potential Logic 
Protection Elements
50AF/50NAF Arc-Flash Detection Instantaneous Overcurrent 
27/59 Over-/Undervoltage 
32 Directional Power  
55 Power Factor 
60 Loss-of-Potential 
81O/81U Over-/Underfrequency 
Second-Harmonic Blocking 
Instrumentation and Control
Arc-Flash Detection Inputs  
Load/Signal Profile Recorder 
Software-Invertible Polarities 
Built-In Web Server 
Harmonic Metering 
RMS Metering 
Configuration SoftwareacSELerator QuickSet SEL-5030 SoftwareSEL Grid Configurator Software
Programmable Digital Inputs (24–250 Vdc/Vac) 
Universal Power Supply (24–250 Vdc/110–240 Vac) 
Communications Ports and Protocols
USB-C Port (Front) 
Setting-Selectable EIA-232/EIA-485 Port (Rear) 
Single 10/100BASE-T Ethernet Port (Rear) 
Dual 10/100BASE-T Ethernet Ports (Rear) 
Modbus RTU and Modbus TCP/IP 
IEC 61850 Edition 2 
DNP3 Level 2 (Serial and LAN/WAN) 
Simple Network Time Protocol 


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