DEHN DSH TNS 255 Type 1+2 Combined Surge Arrester for TN-S Systems

Lightning strikes and switching surges can destroy sensitive electrical equipment in milliseconds. The DEHN DSH TNS 255 is a ready-to-connect, base-mounted combined Type 1+2 surge protective device (SPD) engineered for three-phase TN-S power systems. It provides robust protection at the service entrance or sub-distribution boards, combining high impulse current discharge capability with a low voltage protection level to ensure continuous operation of connected loads.

Who is it for

Electrical contractors, panel builders, and facility managers who need reliable surge protection for industrial plants, commercial buildings, or infrastructure with TN-S earthing. It is ideal for new installations or retrofits where space is limited and a compact, DIN-rail mounted solution is required.

Main features

• Combined Type 1+2 arrester according to IEC/EN 61643-11 for TN-S systems (3-phase, 5-wire).
• High impulse current discharge capacity: 7 kA (10/350 µs) per path L-N and N-PE.
• Nominal discharge current 20 kA (8/20 µs) and follow current extinguishing capability 50 kA rms.
• Low voltage protection level ≤ 1.5 kV for effective protection of downstream equipment.
• Compact 4-module (4 TE) design for 35 mm DIN rail mounting, with red thermoplastic housing (UL 94 V-0).
• Wide operating temperature range from -40 °C to +80 °C.
• Short-circuit withstand capability 50 kA rms with max. backup fuse 160 A gG (fuse not integrated).

Specifications

• SPD type: Type 1 + Type 2 Combined Arrester
• Network system: TNS (3-phase, 5-wire)
• Nominal voltage (U_N): 230 / 400 V AC
• Max. continuous operating voltage (U_C): 255 V AC
• Nominal discharge current (I_n) (8/20 µs): 20 kA (L-N / N-PE)
• Impulse current (I_imp) (10/350 µs): 7 kA (L-N / N-PE)
• Voltage protection level (U_p): ≤ 1.5 kV (L-N / N-PE)
• Follow current extinguishing capability (I_fi): 50 kA rms
• Response time (t_A): ≤ 100 ns
• Operating temperature range: -40 °C to +80 °C
• Mounting type: 35 mm DIN rail
• Number of modules: 4 TE (4 x 17.5 mm)
• Short-circuit withstand capability (I_SCCR): 50 kA rms (with max. backup fuse)
• Max. backup fuse: 160 A gG
• Degree of protection: IP20
• Housing material: Thermoplastic, red, UL 94 V-0
• Standards compliance: IEC 61643-11 / EN 61643-11
• Integrated backup fuse: No

Tips

For optimal protection, install the DSH TNS 255 as close as possible to the incoming supply and ensure proper earthing. Always use the recommended backup fuse (max. 160 A gG) to maintain short-circuit withstand capability. Regular inspection of the status indication is advised to ensure continued protection.