| DC TVS Diode Protector | A semiconductor avalanche device clamps fast transient overvoltage by diverting surge current away from sensitive circuits. | Electronic control boards, communication ports, sensors, instrumentation, battery-management interfaces and low-power DC equipment. | Very fast response; commonly selected by working voltage, standoff voltage, clamping voltage, peak pulse current and pulse energy. | Compact, fast and suitable for protecting low-voltage electronics against repetitive short-duration transients. | Limited surge-energy capability compared with larger power SPDs; incorrect voltage selection can cause overheating or unwanted conduction. | Place close to the protected circuit, keep leads short, confirm polarity for unidirectional devices, and inspect for thermal discoloration or failed short-circuit conditions. | Manufacturer electrical ratings, IEC 61643-31 for photovoltaic DC SPDs where applicable, and the equipment designer’s transient-immunity requirements. |
| DC Metal-Oxide Varistor (MOV) SPD | A voltage-dependent resistor changes to a low-resistance state during a surge and returns toward a high-resistance state afterward. | DC distribution panels, battery systems, photovoltaic combiner boxes, telecom power and industrial control cabinets. | Selected by maximum continuous operating voltage, nominal discharge current, maximum discharge current, clamping voltage and thermal capability. | Good energy-handling capability, practical cost, and availability in modular DIN-rail or panel-mounted formats. | Aging can increase leakage current; sustained overvoltage or excessive energy may lead to thermal failure, so thermal disconnection is important. | Choose a DC-rated device with continuous voltage above the system’s maximum steady-state voltage; verify backup overcurrent protection, wiring torque and status indication during service. | IEC 61643-31 for photovoltaic applications, IEC 61643-41 for low-voltage DC systems where applicable, and the relevant national installation code. |
| Gas Discharge Tube (GDT) Protector | A sealed gas-filled device becomes conductive when the applied voltage exceeds its breakdown level, providing a high-current discharge path. | Telecommunication lines, outdoor signal circuits, long cable runs, remote monitoring systems and galvanically isolated interfaces. | High surge-current capability and very low off-state leakage; response is generally slower than semiconductor protectors and depends on voltage rise rate. | Handles substantial surge current and provides strong galvanic isolation during normal operation. | Higher let-through voltage during the initial transient; DC follow current may persist in some circuits and must be considered in the system design. | Use coordinated protection when sensitive electronics require lower residual voltage; check insulation coordination, grounding paths and signs of end-of-life damage. | IEC 61643-21 for telecommunications and signalling network protection, plus applicable insulation-coordination requirements. |
| Hybrid TVS-MOV or GDT-MOV SPD | Combines components with different response speeds and energy capabilities to provide staged clamping and improved coordination. | Industrial automation, photovoltaic DC circuits, battery energy storage, outdoor electronics and equipment exposed to both fast and high-energy surges. | Performance depends on coordination between stages, internal impedance, voltage ratings, discharge current and thermal protection. | Balances fast response with higher surge-energy handling and can reduce residual voltage at the protected load. | More complex selection and installation; poorly coordinated stages may fail to share surge energy correctly. | Follow the specified line arrangement and conductor lengths, install the recommended backup protection, and replace the complete module if the status indicator shows failure. | Applicable parts of the IEC 61643 series, product test reports, and the manufacturer’s coordination and backup-protection instructions. |
| DC Type 1 SPD | Designed to discharge high-energy surge currents associated with direct or partial lightning-current exposure at the service or facility entry point. | Large photovoltaic installations, facilities with external lightning-protection systems, DC service entrances and exposed industrial sites. | Tested using a higher-energy impulse-current regime than Type 2 devices; exact ratings depend on the system voltage and installation category. | Provides the first high-energy protection stage where lightning current may enter the DC installation. | Usually not sufficient as the only protection for sensitive downstream electronics; requires correct bonding and coordinated downstream SPDs. | Install at the boundary where the external lightning-protection zone changes, minimize conductor length, use the specified bonding arrangement, and inspect after major lightning events. | IEC 61643-11 and IEC 61643-31 classification and testing requirements, together with IEC 62305 lightning-protection principles. |
| DC Type 2 SPD | Limits residual and induced overvoltage after the primary protection stage or protects installations not directly exposed to lightning current. | PV combiner boxes, DC distribution boards, battery cabinets, charging infrastructure and industrial control panels. | Commonly tested with an 8/20 microsecond current waveform; selection uses maximum continuous operating voltage, nominal discharge current and voltage-protection level. | Suitable for most secondary DC distribution points and available in replaceable modular configurations. | May not withstand direct lightning-current duty; incorrect coordination or excessive cable length can increase the voltage reaching the load. | Install near the protected equipment or distribution board, maintain short and straight conductors, verify DC polarity, and check the mechanical and visual condition periodically. | IEC 61643-11 for low-voltage systems and IEC 61643-31 for photovoltaic DC applications; local electrical rules also apply. |
| DC Type 1+2 Combination SPD | Integrates high-energy lightning-current discharge and secondary overvoltage limitation in one coordinated device. | Compact PV systems, remote installations, rooftop arrays, battery sites and panels where separate Type 1 and Type 2 units are impractical. | Carries both Type 1 and Type 2 classifications only when verified by the applicable product test requirements; ratings remain voltage- and configuration-specific. | Simplifies system architecture while providing two levels of protection in a single enclosure. | Higher purchase cost than a basic Type 2 unit and still requires correct earthing, bonding, backup protection and system coordination. | Confirm the product’s tested classification, select the correct number of poles and grounding arrangement, and replace the module after an end-of-life indication. | IEC 61643-11 or IEC 61643-31 as applicable, plus IEC 62305 for lightning-risk and bonding considerations. |
| Photovoltaic DC SPD | Protects PV strings, combiner boxes, inverters and associated DC wiring from lightning-induced and switching transients. | Rooftop solar, ground-mounted solar farms, floating PV, microgrid installations and DC-coupled energy storage. | Must be rated for the PV array’s maximum open-circuit voltage, including low-temperature correction, and for the specific earthing and pole arrangement. | Designed for the electrical and environmental conditions of PV circuits, including continuous DC voltage and outdoor exposure. | A standard AC SPD is not automatically suitable for a PV circuit; DC arc behavior, leakage, enclosure rating and system polarity must be addressed. | Install at the array and inverter ends when required by cable length and risk assessment, use UV- and weather-resistant wiring, and inspect connectors, grounding and status windows. | IEC 61643-31, IEC 60364-7-712, IEC 62548 and IEC 62305 where lightning protection is relevant. |
| Battery and Energy-Storage DC SPD | Diverts transient energy from battery DC buses and connected power-conversion equipment while coordinating with battery protection systems. | Lithium-ion and other rechargeable battery systems, UPS DC links, microgrids, electric-vehicle infrastructure and data-center energy storage. | Requires compatibility with maximum battery voltage, continuous charging voltage, prospective short-circuit current, grounding scheme and available fault protection. | Reduces transient stress on battery-management systems, contactors, converters and monitoring electronics. | The SPD does not replace battery fuses, disconnects or thermal-management controls; stored energy can make DC faults hazardous. | De-energize and verify absence of voltage before service, follow arc-flash and battery safety procedures, use the specified backup protection, and inspect after surge events. | IEC 61643-41 where applicable, IEC 62477-1 for power-electronic systems, IEC 62933 series for energy-storage system considerations, and local battery codes. |
