# BR-20 3+1 Type 2 20kA Surge Protective Device for TT and TNS Systems
## Introduction to Surge Protection
In today’s increasingly electrified world, protecting electrical systems from transient overvoltages is more critical than ever. The BR-20 3+1 Type 2 20kA surge protective device (SPD) offers robust protection for both TT and TNS earthing systems, safeguarding your equipment against damaging electrical surges.
## Key Features of the BR-20 SPD
The BR-20 3+1 configuration provides comprehensive protection with these notable features:
– 20kA discharge capacity per mode (Iimp)
– Type 2 classification according to IEC 61643-11
– Suitable for both TT and TNS earthing systems
– 3+1 protection mode configuration
– Compact design for easy installation
– Visual status indication for quick monitoring
## Understanding the 3+1 Protection Concept
The “3+1” configuration refers to the SPD’s protection modes:
– Three active conductors (L1, L2, L3) protected against phase-to-neutral surges
– One neutral conductor protected against neutral-to-earth surges
This configuration provides complete protection for all possible surge paths in three-phase systems while maintaining compatibility with different earthing arrangements.
## Applications in TT and TNS Systems
The BR-20 is specifically designed to work effectively in both TT and TNS earthing systems:
### TT System Protection
In TT systems where the neutral and earth are separated, the BR-20 provides essential protection against:
– Direct lightning strikes to power lines
– Switching surges from utility equipment
– Internal switching operations within the facility
### TNS System Protection
For TNS systems with combined neutral and earth conductors, the BR-20 offers:
– Protection against common mode surges
– Differential mode surge suppression
– Safe discharge of surge currents to earth
## Installation Considerations
When installing the BR-20 SPD:
– Mount close to the main distribution board
– Ensure proper earthing connections
– Follow local electrical codes and regulations
– Consider upstream coordination with other SPDs
– Verify proper cable sizing for connections
## Maintenance and Monitoring
The BR-20 includes visual indicators to monitor its status:
– Green LED indicates normal operation
– Red LED signals end-of-life condition
– No moving parts for reliable long-term operation
– Recommended periodic inspection as part of maintenance routine
## Technical Specifications
Parameter | Value
Type | 2 (Class C)
Nominal Discharge Current (In) | 20kA (8/20μs)
Maximum Discharge Current (Imax) | 40kA (8/20μs)
Voltage Protection Level (Up) | ≤ 1.5kV
Response Time | < 25ns
Operating Temperature Range | -40°C to +80°C
## Conclusion
The BR-20 3+1 Type 2 20kA surge protective device provides reliable, high-performance protection for electrical installations in both TT and TNS earthing systems. Its robust design, comprehensive protection modes, and clear status indication make it an excellent choice for safeguarding sensitive equipment against damaging electrical surges in commercial and industrial applications.
