LSP provides a complete Type 2 DC Surge Protection Device product portfolio designed for low-voltage DC systems (12V–460V DC), serving industrial control, telecom power distribution, security monitoring, battery energy storage, LED lighting, and EV charging station control circuits.
These surge protectors are tested with 8/20µs surge waveforms (Imax 40kA), providing secondary protection against induced lightning and switching surges, making them the most widely used protection level in low-voltage DC systems.
Prior to the release of IEC 61643-41 standard, low-voltage DC surge protectors were long executed with reference to IEC 61643-11 (AC system standard). Since IEC 61643-11 applies to AC systems, low-voltage DC SPDs were classified under the AC branch in the standard system.
LSP’s current products strictly comply with IEC/EN 61643-41:2025 standard, covering SLP-DC series (95V-460V DC), SLP20-DC series (12V-255V DC), SLP30-DC series (95V-350V DC) and SLP40-DC series (95V-460V DC) to adapt to different voltage level DC distribution requirements.
Type 2 / Class II / Class C
Secondary protection for induced and switching surges in low-voltage DC systems.
8/20 µs Standard Surge Waveform
12V–460V DC Full Voltage Coverage
IEC / EN 61643-41:2025
Type 2 DC SPD is a secondary surge protection device designed for low-voltage DC systems, tested with 8/20µs waveform for induced surge and switching surge protection, suitable for secondary protection locations such as indoor distribution panels and DC control cabinets.
This series is certified to IEC/EN 61643-41:2025 standard, covering 12V–460V full voltage range, widely applied in industrial control, telecom power distribution, security monitoring, battery energy storage, and EV charging station control circuits.
The device adopts DC-specific design, consisting of MOV protection elements, open circuit failure mode (OCM), arc prevention baffles, pluggable module, low-temperature tripping device, flame retardant housing, and remote signaling terminal.
Optimized for DC systems without zero-crossing point, designed per IEC/EN 61643-41:2025, adapted for 8/20µs surge waveform testing (Imax 40kA).
MOV serves as voltage-limiting protection element, conducting and discharging current after surge threshold is reached, automatically returning to high impedance after voltage recovery. SLP-DC series uses high-energy MOVs, meeting Type 2 induced surge protection requirements. Type 2 DC SPD uses MOV only, without GDT, avoiding potential follow current risks from GDT in DC systems
Arc prevention baffles at DC input terminals increase creepage distance, preventing arc propagation through physical isolation. Recessed line inlets prevent operator contact with live parts, meeting safety protection requirements
Modular pluggable structure supports quick replacement, no need to dismantle entire device after MOV aging. Green/red status indicator window provides visual warning, green indicates normal operation, red indicates module replacement needed, reducing maintenance cost and downtime
The device adopts open circuit failure mode, automatically disconnecting the circuit after MOV aging while system continues operation. DC systems have no zero-crossing point, short circuit failure (SCM) causes sustained arc and fire risk, OCM is the only allowed natural failure mode mandated by IEC/EN 61643-41:2025
The device adopts low-temperature tripping technology, with response 20% faster than traditional Type 2 DC SPDs. Tripping device activates quickly when MOV overheats, ensuring safe disconnection and system reliability
Housing material PA6+GF30% passes glow wire test. Remote signaling terminal monitors SPD status in real time, triggering alarm signals on fault, supporting quick maintenance response
Type 2 DC Surge Protection Device is a secondary protection device for low-voltage DC systems, specifically designed for induced surges and switching overvoltages, tested with 8/20 µs waveform.
Suitable for 12V–460V DC energy storage, telecom, industrial automation applications, complying with IEC/EN 61643-41:2025 standard, protecting downstream equipment through metal oxide varistor (MOV) voltage-limiting technology.
Type 2 DC Surge Protection Device provides secondary protection against induced surges and switching overvoltages in low-voltage DC systems, verified for nominal discharge current (In) and maximum discharge current (Imax) using 8/20 µs waveform, complying with IEC/EN 61643-41:2025 standard.
The device uses metal oxide varistors (MOV) as core protection components, quickly conducting when surges invade to clamp overvoltages within equipment withstand limits, automatically returning to high-impedance state after surge discharge to provide continuous downstream protection.
DC circuits have no zero-crossing, making arc self-extinguishing difficult. The device uses open circuit failure mode (OCM) to ensure continued system operation after failure, avoiding fire risks caused by short circuits. Suitable for 12V–460V DC energy storage systems, telecom rooms, industrial automation, smart buildings, and supports TN, TT, IT DC earthing systems.
Type 2 testing uses 8/20 µs waveform to simulate induced surges, verifying device rapid response and repetitive discharge capability. This waveform corresponds to In and Imax parameters, comprehensively evaluating SPD protection performance in low-voltage DC systems. The device passes IEC/EN 61643-41:2025 standard testing, ensuring reliable surge current discharge under 8/20 µs waveform.
8/20 µs Waveform Characteristics
8/20 µs waveform has 8 µs front time and 20 µs half-peak time, fast rise time but short duration. This waveform simulates induced lightning and switching surges, occurring at higher frequency than direct lightning. Front time 8 µs means voltage reaches peak within 8 microseconds, testing SPD response speed.
Induced Surge Simulation
Induced lightning generates induced voltage on metal lines, switching operations (circuit breakers, relays) generate switching overvoltages. These surges have relatively low energy but high frequency, are the main threats faced by low-voltage DC systems. 8/20 µs waveform accurately simulates the fast-rise characteristics of such surges.
In and Imax Testing
In testing uses 8/20 µs waveform for 15 repeated impacts, verifying device repetitive discharge capacity. Imax testing uses 8/20 µs waveform for single impact, verifying device maximum withstand capacity. SLP-DC series In = 20kA, Imax = 40kA, meeting most industrial application requirements.
Waveform and Protection Level
Type 2 SPD is specifically designed for 8/20 µs waveform, does not handle 10/350 µs direct lightning current. Direct lightning protection requires Type 1 or Type 1+2 SPD. 8/20 µs waveform energy is approximately 1/100 of 10/350 µs waveform, Type 2 SPD offers optimal cost, is the mainstream choice for low-voltage DC systems.
Type 2 DC SPD uses metal oxide varistor (MOV) as the core protection element. During normal operation, MOV presents high-impedance state, not affecting system operation. When surge voltage arrives, MOV rapidly conducts, discharging overvoltage to ground terminal, protecting downstream equipment. After surge, MOV automatically returns to high-impedance state, system continues normal operation.
Two Core Actions
High-Impedance State: During normal system operation, MOV resistance is very high, acting like an insulator, no current flows.
Conduction and Discharge: When surge voltage exceeds MOV triggering voltage, MOV resistance drops, conducting surge current to ground terminal, voltage is clamped to safe level.
Special Design for DC Systems
DC circuits have no zero-crossing, making arc self-extinguishing difficult. The device uses arc-prevention baffles to increase creepage distance, preventing sustained arc from short circuits. When MOV ages or fails, the device automatically disconnects (open circuit failure), ensuring continued system operation, avoiding fire caused by short circuits.
Type 2 DC SPD adopts common mode protection paths, installing MOV protection elements between positive-to-ground and negative-to-ground respectively. DC systems have no zero-crossing, making arc self-extinguishing difficult, grounding design must ensure rapid surge energy discharge. Device uses equipotential bonding and short-path grounding, reducing grounding impedance, improving protection effectiveness.
Common Mode Protection Paths
Common mode protection paths are (DC+)-PE and (DC-)-PE, suppressing positive-to-ground surges and negative-to-ground surges respectively. Positive and negative poles protect independently, covering all line-to-ground fault scenarios, ensuring comprehensive DC system protection. Common mode protection applies to TN, TT, IT DC earthing systems, being the primary protection method for low-voltage DC systems. Device uses 2-pole design, each pole configured with one MOV element, achieving independent protection.
Differential Mode Protection Paths
Differential mode protection paths are line-to-line, such as (DC+)-(DC-), suppressing inter-pole surges. This product focuses on common mode protection, does not provide differential mode protection function. If differential mode protection is needed, additional differential mode SPD should be configured at equipment front-end, achieving full-mode protection. Differential mode protection typically applies to special scenarios, such as long-distance cable transmission systems.
Grounding Design Principles
SPD grounding conductor must connect to main equipotential bonding system, ensuring grounding resistance meets standard requirements. Grounding path should be short and direct, avoiding loop inductance affecting surge discharge effectiveness. Grounding conductor cross-section must meet current carrying capacity, ensuring conductor does not heat or damage during large current surges. DC system grounding must consider polarity, positive and negative pole grounding paths should be configured independently.
SLP-DC series offers three voltage ranges, covering applications from 12V low-voltage DC to 460V industrial distribution. Tested per IEC/EN 61643-41:2025, devices use MOV voltage-limiting elements and open circuit failure mode, ensuring surge protection safety for 12V–460V DC systems.
Uc (Maximum Continuous Operating Voltage)
Uc indicates maximum continuous operating voltage, must exceed actual maximum system voltage. 12V systems use Uc 125Vdc, 220V systems use Uc 275Vdc, 350V systems use Uc 460Vdc. Uc selection considers float voltage superposition and system ripple, maintaining insulation margin.
In (Nominal Discharge Current)
8/20 µs waveform verifies In, reflecting repetitive discharge capacity. SLP-DC series In is 20kA, meeting 15 repeated impact test requirements. In is device rated capacity, suitable for daily induced surge protection.
Imax (Maximum Discharge Current)
8/20 µs waveform verifies Imax, reflecting single-surge maximum withstand capacity. SLP-DC series Imax is 40kA, providing discharge margin. Higher Imax means stronger capability to handle extreme surges.
Up (Voltage Protection Level)
Up indicates device residual voltage level, reflecting equipment withstand matching. SLP-DC series Up is controlled at 0.3kV–1.8kV, increasing with voltage rating. Up must be below equipment insulation withstand limit, ensuring equipment safety.
| Parameter | SLP20-DC Series | SLP30-DC Series | SLP40-DC Series |
| Uc Range | 125–255 Vdc | 150–350 Vdc | 125–460 Vdc |
| Un Range | 12–220 Vdc | 95–280 Vdc | 95–350 Vdc |
| In (8/20 µs) | 20 kA | 20 kA | 20 kA |
| Imax (8/20 µs) | 40 kA | 40 kA | 40 kA |
| Up | ≤ 0.5 kV | ≤ 1.2 kV | ≤ 1.8 kV |
| Poles | 2P | 2P | 2P |
| Application | Telecom, Industrial Control | Industrial, Energy Storage | Large-Scale Energy Storage, Automation |
Type 2 DC SPD is optimized for 8/20 µs induced surges, covering 12V–460V DC wide voltage range, meeting requirements for energy storage, telecom, industrial automation applications. Device adopts pluggable module design, enabling quick replacement after aging, reducing maintenance cost. DC systems have no zero-crossing, device uses arc-prevention baffles and open circuit failure mode, ensuring safe system operation.
Arc-prevention baffles at DC input terminals increase creepage distance, forcibly extinguishing arc through physical isolation. DC circuits have no zero-crossing, making arc self-extinguishing difficult, arc-prevention design prevents sustained arc from short circuits. Recessed line inlets prevent operator contact with live parts, meeting IP20 protection level, ensuring personnel safety.
Device adopts low-temperature tripping technology, response speed 20% faster than traditional Type 2 DC SPDs. Tripping device activates quickly when MOV overheats, ensuring safe disconnection, enhancing arc extinction capability. Fast response improves system reliability, avoiding safety hazards caused by heat accumulation.
Type 2 DC SPDModular pluggable structure supports quick replacement, no need to dismantle entire device after MOV aging. Green/red status indicator window provides visual warning, green indicates normal operation, red indicates module replacement needed. Module replacement time less than 30 seconds, reducing 70% maintenance downtime, module replacement cost only 1/3 of complete device replacement.
Type 2 DC SPD series covers 12V–460V DC voltage range, single series meets full low-voltage DC scenario requirements. Device offers three voltage ratings (SLP20-DC, SLP30-DC, SLP40-DC), adapting to different voltage levels such as 12V telecom systems, 220V industrial distribution, 460V large-scale energy storage. Wide voltage coverage simplifies selection process, reducing inventory cost.
Device provides remote signaling terminal, monitoring Type 2 DC SPD operating status in real time. SPD aging or failure triggers alarm, signal transmitted to BMS or SCADA system. Remote monitoring function supports preventive maintenance, improving system operation efficiency, ensuring surge protection remains effective.
Type 2 DC SPD undergoes standardized testing to verify electrical performance, safety, and environmental adaptability. Testing covers 8/20 µs impulse current and voltage test, MOV parameter verification, GDT parameter verification, thermal stability test, glow wire test, and salt spray test. The device complies with IEC/EN 61643-41 standard, ensuring reliable operation in 95V–460V DC low voltage DC systems.
Type 2 DC Surge Protector at LSP adopts an integrated R&D and production system for manufacturing, covering component selection, assembly processes, and electrical performance verification.
Before leaving the factory, products undergo electrical parameter testing and surge performance verification to meet low-voltage DC system application requirements and ensure performance consistency under specified surge conditions, suitable for 12V–460V DC voltage range.
The production process strictly follows the ISO 9001:2015 quality management system, ensuring product compliance and production efficiency. Type 2 DC SPD is certified by TUV, CB, and CE, and can be directly used in systems or sold globally, complying with international standards such as IEC/EN 61643-41:2025.
Type 2 DC SPD enjoys a 5-year warranty, with a 7-day return and 30-day exchange policy. Shipping costs and tariffs during the warranty period are borne by LSP, reducing customer procurement risk and after-sales costs.
Possesses independent surge protector R&D capability. The R&D team with 20 years of experience provides technical support, from requirement analysis, solution design to on-site implementation, customizing the most suitable Type 2 DC SPD solutions for customers.
Provides more value to key customers, including high-quality corrugated cardboard packaging, 3D animation marketing materials, and regulatory and certification support, enhancing product market competitiveness.
An experienced team manages inventory and production, maintaining stable material inventory to cope with peak periods. Standard Type 2 DC SPD orders are shipped within 15 days, custom orders within 30 days, with a 96% on-time rate.
Establishes a comprehensive quality control system from raw material inspection to finished product testing. Every Type 2 DC SPD undergoes 8/20μs surge impact testing, thermal stability testing, 48-hour salt spray testing, glow wire testing, and TOV testing, ensuring product quality and reliability.
LSP adopts the ISO 9001:2015 quality management system, with an independent R&D team with 20 years of experience and automated production lines, ensuring that every stage from R&D to delivery of Type 2 DC SPD (12V–460V DC) meets international standards. Products are certified by TUV, CB, CE and other authoritative certifications, providing 5-year warranty, 7-day return, and 30-day exchange policies. Standard orders are delivered within 15 days, custom orders within 30 days, with a 96% on-time rate, providing reliable procurement assurance for customers.
Type 2 DC SPD operates in global projects across telecommunications, data centers, industrial control, security, and rail transit. The following feedback comes from on-site engineers and project managers, including specific operational data and maintenance records.
A DC SPD Type 2 provides fast and reliable protection against transient overvoltages in low-voltage DC systems. It limits overvoltage peaks to safe levels, ensuring the protection of batteries, PLCs, sensors, and other sensitive DC equipment. By integrating DC SPD Type 2 devices, systems achieve reduced downtime, improved equipment lifespan, and enhanced overall reliability.
Type 2 DC SPDs primarily defend against switching surges and residual lightning currents that remain after Type 1 SPD intervention. They are not intended to directly absorb high-energy direct lightning strikes. Designed for low-voltage DC systems, Type 2 DC SPDs safeguard sensitive electronics, battery systems, PLCs, and DC sensors, ensuring continuous operation even under repeated surge events.
DC SPD Type 2 devices act as secondary or distribution-level protection, reducing residual surges from upstream Type 1 SPDs. They provide layered protection, ensuring reliable and cost-effective safety for all DC equipment. By selecting Type 2 DC Surge Protection Devices, users can achieve coordinated protection for industrial, residential, telecom, and energy storage systems.
DC SPD Type 2 devices are designed in compliance with IEC 61643-11 standards. Their DIN-rail mounting and pluggable module design enable safe and easy installation, simplified maintenance, and consistent performance. These standards ensure that Type 2 DC Surge Protective Devices deliver reliable surge suppression and meet international safety and quality requirements.
Type 2 DC SPDs are the second stage in a layered protection system. Working downstream of Type 1 SPDs, they protect equipment from residual surges while operating alongside AC SPDs to provide complete graded protection for both DC and AC circuits. Proper coordination of Type 2 DC Surge Protectors ensures system reliability, reduces equipment stress, and enhances overall surge resilience.
Yes. DC SPD Type 2 devices safeguard sensors, control modules, PoE devices, and other DC electronics in industrial and telecom applications. When combined with AC SPDs and a multi-level protection strategy, Type 2 DC SPDs maintain operational continuity, prevent downtime, and ensure the reliability of critical systems in high-risk environments.
Type 2 DC SPD is the baseline protection solution for low-voltage DC systems, targeting 8/20µs induced surges and switching overvoltages, suitable for LPZ 1/2 areas; Type 1+2 provides combined direct lightning and induced surge protection, only configured in specific scenarios. Type 2 covers 80% of low-voltage DC scenarios as the most cost-effective solution.
Type 2 DC SPD and Type 1+2 DC SPD are two types of differentiated protection devices defined by IEC 61643-41:2025 standard: Type 2 focuses on 8/20µs induced surge and switching overvoltage protection, using MOV components to achieve fast voltage clamping, response time < 25ns, voltage protection level (Up) ≤ 1.2kV, complying with open circuit failure mode (OCM) requirements; Type 1+2 provides combined 10/350µs direct lightning and 8/20µs induced surge protection, with core technology divided into two categories: FLP25-DC75 series uses MOV + GDT combination technology, while FLP7/FLP-DC series uses high-energy MOV single technology.
The technical differences between the two types are significant: Type 2 has no lightning impulse current (Iimp) index, only tested with 8/20µs waveform, suitable for LPZ 1/2 areas (indoor distribution panels, equipment-side), requiring no additional grounding construction; Type 1+2 requires dual testing of 10/350µs and 8/20µs waveforms, with Iimp ≥ 4kA direct lightning protection capability, suitable for LPZ 0/1 boundaries (building main entrances, outdoor energy storage), FLP25-DC75 series blocks direct lightning follow current through GDT, while FLP7/FLP-DC series uses high-energy MOV for direct discharge.
| Technical Parameter | Type 2 DC SPD | Type 1+2 DC SPD (FLP25-DC75 Series) | Type 1+2 DC SPD (FLP7/FLP-DC Series) | Engineering Significance |
| Test Waveforms | 8/20µs only | 10/350µs + 8/20µs | 10/350µs + 8/20µs | Type 1+2 provides direct lightning protection |
| Lightning Impulse Current Iimp | No such test | 25kA 10/350µs | 4kA–7kA 10/350µs | Direct lightning protection capability varies by series |
| Nominal Discharge Current In | 20kA 8/20µs | 25kA 8/20µs | 20kA 8/20µs | Consistent induced surge discharge capability |
| Maximum Discharge Current Imax | 40kA 8/20µs | 70kA 8/20µs | 40kA–70kA 8/20µs | Some Type 1+2 series have stronger extreme surge tolerance |
| Voltage Protection Level Up | ≤ 1.2kV | ≤ 0.5kV | ≤ 1.2kV | FLP25-DC75 series has lower residual voltage |
| Protection Components | MOV only | MOV + GDT combination | MOV only | Different technical implementation paths |
| Response Time | < 25ns | < 25ns | < 25ns | All provide fast response capability |
| Failure Mode | Open Circuit (OCM) | Open Circuit (OCM) | Open Circuit (OCM) | All comply with IEC 61643-41 standard |
| Typical Installation Location | LPZ 1/2 area | LPZ 0/1 boundary | LPZ 0/1 boundary | Consistent protection area positioning |
| Cost Characteristic | Cost-optimized | Higher | Medium | FLP7/FLP-DC series offers better cost-performance |
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