DEHN DSH B TT 255 FM Type 1+2 Combined Lightning Current and Surge Arrester

Type 1+2 combined lightning current and surge arrester for three-phase TT and TN-S systems, delivering robust protection with a total lightning impulse current of 50 kA (10/350 µs). Its spark-gap technology safely discharges high-energy surges at the service entrance, ensuring reliable defence for low-voltage installations.

Advantages

Combines Type 1 and Type 2 protection in one compact module, eliminating the need for separate devices and simplifying installation. High follow current extinguishing capability of 50 kA rms ensures reliable interruption of mains follow currents. Integrated potential-free changeover contact enables remote monitoring of arrester status. 35 mm DIN rail mounting and IP20 design allow easy integration into distribution boards.

Suitable for

• Three-phase TT and TN-S systems requiring lightning equipotential bonding
• Service entrance protection in residential, commercial, and industrial buildings
• Installations with nominal voltage 230/400 V AC and max continuous operating voltage 255 V AC
• Applications where remote signalling of arrester status is necessary

Key specifications

• Lightning impulse current (10/350 µs): 12.5 kA per pole, 50 kA total
• Nominal discharge current (8/20 µs): 20 kA per pole
• Max. discharge current (8/20 µs): 50 kA per pole
• Voltage protection level: ≤ 1.5 kV at Iimp, ≤ 1.0 kV at In
• Response time: ≤ 100 ns
• Operating temperature range: -40 °C to +80 °C
• Standards: IEC 61643-11 / EN 61643-11

Recommendations

Ideal for service entrance protection in buildings with TT or TN-S earthing systems, especially where remote status monitoring is required. Pair with a suitable backup fuse up to 315 A gG for optimal performance.