​Chint Surge Protective Device (SPD) NXU-I+II 12.5/275

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:

I. Technical Parameters and Protection Capability

1. 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.

2. 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.

 II. Design Features and Reliability

1. 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.

2. 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

1. 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.

2. 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.

 IV. Application Scenarios and Selection Recommendations

1. 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.

2. 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.

 V. Market Reference and Purchase Recommendations

1. 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

 I. 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.