# Lightning Protection BR-20 4P Type 2 20kA Surge Protective Device for TNS Systems
## Introduction to Surge Protection in TNS Systems
The BR-20 4P Type 2 20kA Surge Protective Device (SPD) is specifically designed for TNS (Terre-Neutre-Séparé) electrical systems, offering robust protection against transient overvoltages caused by lightning strikes and switching operations. This advanced protection device plays a critical role in safeguarding electrical installations and connected equipment from potentially damaging power surges.
## Key Features of the BR-20 4P SPD
High-Performance Protection
With a nominal discharge current (In) of 20kA per pole, the BR-20 4P provides superior protection for all phases and neutral in TNS systems. Its Type 2 classification ensures it can handle indirect lightning strikes and major switching transients effectively.
System Compatibility
Designed specifically for TNS earthing systems, this 4-pole SPD offers comprehensive protection by monitoring all live conductors (L1, L2, L3) and the neutral conductor. This makes it ideal for three-phase installations where complete system protection is required.
Advanced Thermal Protection
The device incorporates thermal disconnection technology that automatically disconnects the SPD from the circuit if it becomes overloaded, preventing potential fire hazards and ensuring safe operation throughout its service life.
## Technical Specifications
- Type: 2 (Class II)
- Nominal Discharge Current (In): 20kA (8/20μs)
- Maximum Discharge Current (Imax): 40kA (8/20μs)
- Voltage Protection Level (Up): ≤ 1.5kV
- Response Time: < 25ns
- Operating Voltage: 230/400V AC
- Frequency: 50/60Hz
- Number of Poles: 4 (3 phases + neutral)
- Mounting: DIN rail (35mm)
## Installation Considerations
Proper Placement in Electrical System
The BR-20 4P should be installed at the main distribution board as the primary surge protection device in a TNS system. It serves as the second level of protection in a coordinated SPD system, complementing Type 1 SPDs at the service entrance.
Wiring Requirements
Proper installation requires short, straight connections to minimize inductive effects. The cross-section of connecting conductors should be appropriate for the expected fault current, typically 6-16mm² depending on local regulations and system requirements.
System Coordination
For optimal protection, the BR-20 4P should be used in conjunction with other SPD types following the cascade principle, ensuring energy coordination between different protection levels in the electrical installation.
## Maintenance and Monitoring
The BR-20 4P features visual status indicators that show the operational state of the device. Regular inspection is recommended to ensure the SPD remains functional, especially after significant surge events. Most models include remote signaling contacts for integration with building management systems.
While the device is maintenance-free in normal operation, it should be replaced after experiencing a major surge event or when the status indicators show end-of-life condition. The typical service life is approximately 10 years under normal operating conditions.
## Benefits of Using BR-20 4P in TNS Systems
- Comprehensive protection for all conductors in three-phase TNS systems
- High surge current capacity for reliable operation during major electrical events
