NPS01-F20 AC 3+1P Surge Protective Device

Economical 3+1 Architecture for Small Three-Phase Four-Wire Systems

 

Product Overview

The NPS01-F20 AC 3+1P Surge Protective Device is an economical Type 2 (Class II) surge protection device designed for small three-phase four-wire power distribution systems. It complies with EN/IEC 61643-11 and GB/T 18802.11 standards and has passed Type 2+3 test certification. The product features the classic 3+1 protection architecture – three-phase varistors combined with a neutral-line dedicated spark gap, with each phase delivering a nominal discharge current In of 10kA (8/20μs) and a maximum discharge current Imax of 20kA, with an open circuit voltage of 6kV. This configuration perfectly matches the protection requirements of TN-S and TT three-phase four-wire earthing configurations for small distribution systems. The 72mm four-pole width fits standard 35mm DIN rail mounting, with Uc covering 275V to 440V (NPE mode 255V). It is widely used in small commercial buildings, office distribution panels, retail power systems, and other small three-phase four-wire terminal systems requiring affordable secondary surge protection.

Each phase circuit uses a high-energy zinc oxide varistor chip with fast response and low residual voltage for rapid surge current discharge. The neutral-to-earth circuit employs a dedicated gas discharge gap module, which operates with zero leakage current and zero power consumption under normal conditions – effectively eliminating neutral line drift and system interference issues caused by long-term leakage current. The phase and neutral protection elements are precisely energy-coordinated, with no follow current and no protection dead zones. The modular independent trip design gives each pole its own thermal disconnector and red/green status indicator window. Single-pole failure triggers automatic isolation without affecting the other poles, making fault location fast and intuitive. The conductive busbar is made of high-purity copper with tin plating, ensuring low contact resistance and high surge current capacity. The UL94V-0 red thermoplastic housing with IP20 rating provides reliable insulation safety.

This series offers a phase-mode voltage protection level Up as low as 0.9kV, with a phase-mode response time of ≤25ns and an N-PE mode response time of ≤100ns, delivering excellent residual voltage control and high protection accuracy. A 40A gG back-up fuse is recommended to achieve optimal selective coordination between upstream and downstream protection stages, preventing nuisance tripping of upstream breakers during lightning strikes. An optional normally open/normally closed floating changeover contact for remote signaling (AC 250V/0.5A) is available for simple monitoring systems. The device operates within -40°C to +80°C and 5% to 95% humidity, and accommodates conductors from 4mm² to 25mm². With 35mm DIN rail quick mounting and a compact 72mm width, this is a cost-effective solution for secondary surge protection in small three-phase four-wire distribution systems.

Inner box dimensions (L*W*H): 11.3*10.1*7.7, 15.11*10.1*7.7
Outer box dimensions (L*W*H): 32.5*27.5*27.5

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