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Views： 5 Author： Mark Zhang Publish Time： 2026-06-12 Origin： 本站
Surge Protective Devices (SPDs) are essential for protecting electrical equipment from transient overvoltages caused by lightning, switching operations, and grid disturbances. This guide explains SPD functions, types, choice criteria, and industry standards to help engineers and buyers make informed decisions. For a full product range, visit Singi Electric SPD products.
A Surge Protective Device (SPD) is a component designed to limit transient overvoltages and divert surge currents away from sensitive equipment. It operates by switching from a high-impedance state to a low-impedance state when voltage exceeds a threshold, clamping the voltage to a safe level. SPDs are classified according to IEC 61643-11, which defines Type 1 (waveform 10/350 µs for direct lightning), Type 2 (8/20 µs for induced surges), and Type 3 (low-energy protection at point of use). Singi Electric offers a comprehensive range of SPDs meeting these standards.
Without SPDs, transient overvoltages can cause immediate equipment failure, data corruption, or gradual degradation of insulation. Industrial facilities, data centers, solar plants, and commercial buildings are vulnerable. Studies show that SPDs reduce the risk of damage from lightning-induced surges by over 80% (see Investigation of Lightning Effects on Solar Power Plants)., SPDs improve system reliability and uptime. Singi Electric SPDs are designed to withstand harsh conditions and provide consistent protection.
Important: Always verify that the SPD's voltage protection level (Up) is lower than the equipment's impulse withstand voltage (Uw). Refer to IEC 61643-11 for coordination guidelines.
SPDs are broadly categorized by application:
| Type | Application | Waveform | Typical Location |
|---|---|---|---|
| Type 1 | Main distribution boards, direct lightning exposure | 10/350 µs | Service entrance |
| Type 2 | Sub-distribution, industrial panels | 8/20 µs | Secondary panels |
| Type 3 | Sensitive terminal equipment | Combination wave | Socket outlets, device inlets |
For solar PV systems, DC SPDs are required on the DC side. Singi Electric provides both AC and DC SPDs compliant with IEC 61643-31 for photovoltaic installations. Research on Ground Potential Rise and SPD Damage highlights the importance of choosing SPDs with sufficient energy handling capability for continuous currents.
Choice involves five key parameters:
Always refer to IEC 60947-1 for general rules on coordination with switchgear. Singi Electric provides detailed technical datasheets to simplify choice.
A: Type 1 SPDs are designed for direct lightning strikes with high energy (10/350 µs waveform), while Type 2 handle induced surges (8/20 µs). Type 1 is installed at the main panel; Type 2 at subpanels.
A: No, SPDs are designed for AC or DC. Using an AC SPD in a DC system may cause failure due to different quenching characteristics. Singi Electric offers dedicated AC and DC series.
A: SPDs have a finite lifespan depending on surge events. Many models include end-of-life indication. Regular inspection and testing according to IEC 61643-11 are recommended.
A: Up (voltage protection level) indicates the maximum voltage the SPD allows through. It must be lower than the equipment's impulse withstand voltage to ensure protection.
SPDs are a fundamental component of modern power systems, safeguarding assets and ensuring uptime. Proper choice based on standards and application requirements is critical. Singi Electric offers a full portfolio of SPDs for AC, DC, and solar applications, backed by rigorous testing and compliance with IEC 61643-11 and related standards. Explore the range at Singi Electric SPD product page.
[1] IEC 61643-11:2011. Low-voltage surge protective devices – Part 11: SPDs connected to low-voltage power systems. Geneva: IEC, 2011.
[2] Investigation of Lightning Effects on Solar Power Plants – SPD Analysis. ArXiv:2511.06523, 2025.
[3] Ground Potential Rise and SPD Damage Caused by Lightning Initial Continuous Current. Journal of Lightning Research, 2023.
Singi Electrica is China manufacturer & supplier who mainly produces miniature circuit breaker, MCCB, SPD,distribution box , junction box with 24 years of experience. Hope to build business relationship with you.
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