DEHN DSH TNS 255 FM Combined Arrester Type 1+2 for TN-S Systems (941405)

The DEHN DSH TNS 255 FM is a combined Type 1+2 surge protective device specifically optimized for TN-S earthing systems. Unlike generic arresters, it integrates lightning current and surge protection in a single 4-pole unit, providing a compact solution for main distribution boards where space and performance are critical.

Highlights

• Combined Type 1+2 protection per IEC/EN 61643-11
• Designed for TN-S systems with 230/400 V AC nominal voltage
• High discharge capacity: 7 kA (10/350 µs) per pole, 28 kA total
• Low voltage protection level ≤ 1.5 kV
• Integrated floating changeover contact for remote signaling
• Thermoplastic enclosure, red, UL 94 V-0, IP20

In daily use

Installed on a 35 mm DIN rail, this arrester offers reliable protection against transient overvoltages. Its follow current extinguishing capability of 50 kA rms and short-circuit withstand of 50 kA rms (with 160 A gG backup fuse) ensure safe operation even under fault conditions. The remote signaling contact allows integration into building management systems for status monitoring.

Full specifications

• SPD type: Type 1+2 combined arrester
• Earthing system: TN-S
• Nominal voltage (Un): 230 / 400 V AC (50/60 Hz)
• Max. continuous operating voltage (Uc): 255 V AC
• Nominal discharge current (In) (8/20 µs): 20 kA
• Impulse current (Iimp) (10/350 µs): 7 kA per pole / 28 kA total
• Voltage protection level (Up): ≤ 1.5 kV (at Iimp) / ≤ 1.2 kV (at In)
• Follow current extinguishing capability (Ifi): 50 kA rms
• Response time (tA): < 100 ns
• Operating temperature range: -40 °C to +80 °C
• Number of poles: 4-pole
• Mounting type: 35 mm DIN rail
• Enclosure material: Thermoplastic, red, UL 94 V-0
• Protection degree: IP20
• Remote signaling contact: Yes (floating changeover contact)
• Standards compliance: IEC 61643-11 / EN 61643-11
• Short-circuit withstand capability (Isccr): 50 kA rms (with max. backup fuse)
• Max. backup fuse: 160 A gG
• Connection cross-section (solid/stranded): 1.5 - 35 mm² / 1.5 - 25 mm²

Final note

The DEHNshield DSH TNS 255 FM is a robust and reliable choice for protecting electrical installations in TN-S systems against both direct lightning strikes and switching overvoltages.