Chint Surge Protective Device (SPD) NXU-I+II 12.5/275 is a dual-protection product specifically designed for low-voltage power distribution systems. It integrates Class T1 (10/350μs waveform) and Class T2 (8/20μs waveform) surge suppression technologies, and is suitable for protecting residential, commercial, and industrial environments against lightning-induced overvoltages and switching overvoltages. Below is a detailed analysis of its core information:
- Technical Parameters and Protection Capability
- Core Performance Indicators
Maximum Continuous Operating Voltage (Uc): 275V (suitable for 230V single-phase or 400V three-phase systems).
Discharge Current:
– Class T1 Iimp (10/350μs): 12.5kA (for discharging direct lightning energy).
– Class T2 Imax (8/20μs): 50kA (for suppressing induced lightning and switching overvoltages).
Voltage Protection Level (Up): ≤1.5kV (L-PE/N-PE paths), effectively protecting equipment from residual voltage damage.
Response Time: ≤25ns, quickly intercepting transient overvoltages.
- Dual Protection Mechanism
Class T1: Uses a Gas Discharge Tube (GDT) to discharge the high energy of direct lightning, reducing the impact load on subsequent circuits.
Class T2: Adopts a Metal Oxide Varistor (MOV) to further limit voltage, ensuring the voltage of terminal equipment stays within a safe range.
Application Scenarios: Suitable for the incoming line terminals of small and medium-sized buildings (such as villas and shops) or areas with moderate thunderstorm activity (30-60 thunderstorm days per year). It needs to be used with downstream Class T2 SPDs (with a distance of ≥10m or additional decouplers) to achieve multi-level protection.
- Design Features and Reliability
- Safety and Durability
Modular Structure: Plug-and-play design for easy maintenance, supporting remote alarm contacts (optional) for real-time monitoring of operating status.
Thermal Trip Protection: When internal components age or overheat, it automatically disconnects the circuit and triggers a red indicator to prompt replacement.
Material and Environmental Adaptability:
– The housing is made of flame-retardant material with an IP20 protection rating, capable of withstanding extreme temperatures from -40℃ to +70℃.
– Suitable for environments with Pollution Degree 2 and an altitude of ≤2000m.
- Certifications and Standards
– Complies with IEC/EN 61643-11 and GB/T 18802.11 standards, and has obtained CQC, CE, and CB certifications, ensuring global applicability and quality reliability.
– Compatible with the NXSCB dedicated protection device (to be purchased separately), which can quickly interrupt circuits in case of short circuits, reducing the risk of fire.
III. Installation and Maintenance Guidelines
- Installation Requirements
Wiring Method: Supports full-mode protection for L-PE, N-PE, and L-N, and is compatible with TT and TN power grid systems.
DIN Rail Installation: Uses TH35-7.5/DIN35 standard rails, with a compact installation size (e.g., 70mm width for the 4P model), saving space in distribution boxes.
Grounding Specifications: The grounding wire must be independent with a cross-sectional area of ≥16mm² to ensure a low-impedance current discharge path.
- Maintenance Key Points
Regular Inspection: Before the thunderstorm season every year, confirm the operating status through the status indicator window (green for normal, red for replacement required) or remote signals.
Replacement Cycle: The service life is approximately 5-8 years under normal use; if frequent lightning strikes occur, early inspection is required.
Warranty Policy: Provides a 36-month warranty from the date of factory shipment; free replacement is available for non-human-induced damages.
- Application Scenarios and Selection Recommendations
- Typical Applications
Residential and Commercial: Protects air conditioners, refrigerators, smart home systems, etc., from lightning impacts.
Industrial and Infrastructure: Suitable for protecting the main incoming lines of equipment such as distribution boxes and control cabinets, especially for sensitive equipment like photovoltaic inverters.
Lightning-Prone Area Protection: Used with downstream Class T2 SPDs (e.g., NXU-II 40kA) to form a three-level protection system, improving system reliability.
- Selection Precautions
Voltage Matching: Select the Uc value (275V or 385V) according to the power grid voltage to avoid component aging caused by long-term overvoltage.
Current Carrying Capacity: If the number of thunderstorm days per year exceeds 60, it is recommended to upgrade to a higher specification (e.g., NXU-I+II 25kA).
Supporting Equipment: Priority should be given to selecting decouplers or backup protection fuses of the same brand (e.g., NSCB5-I+II 12.5H) to ensure compatibility.
- Market Reference and Purchase Recommendations
- Price Range
– The price of the 4P model is approximately 78-186 RMB on mainstream e-commerce platforms (such as Tmall and JD.com) in 2025, with specific fluctuations depending on channels and functional differences (e.g., with remote signaling contacts).
– For bulk industrial purchases, discounts can be obtained through Chint-authorized distributors; system parameters (such as cable length and lightning strike risk level) need to be provided for customized solutions.
– WhatsApp for inquiries in 2025: 0086-13811255435
- User Reviews and Reputation
Advantage Feedback: Users generally recognize its easy installation and stability, especially its excellent performance in lightning-prone areas.
Precautions: Some users suggest adding moisture-proof measures in high-humidity environments to prevent performance impacts caused by condensation.
Summary
With its dual protection mechanism, high-reliability design, and wide applicability, Chint NXU-I+II 12.5/275 Surge Protective Device has become an ideal choice for low-voltage power distribution systems. Its strict standard certifications, clear status indication, and convenient maintenance features can effectively reduce damage to equipment caused by lightning strikes and switching overvoltages, providing long-term safety protection for residential, commercial, and industrial users. When selecting the product, it is necessary to consider the actual application scenario and power grid parameters; if necessary, consult professional engineers to optimize the protection scheme.
