LSP is a trusted manufacturer of overvoltage protection devices (AC and DC SPDs) in China, supplying reliable overvoltage protection solutions for industrial machinery, commercial systems, and energy generation projects. Building on extensive international standards compliance, LSP provides a comprehensive range of AC/DC Surge Protection Devices (SPDs), including DIN-rail mounted AC transient overvoltage protection. With proven engineering expertise, every device—from standard designs to customized circuit protection solutions—meets global regulations and delivers reliable protection against transient overvoltages.
LSP offers a full range of overvoltage protection devices, including Type 1, Type 2, and Type 3 AC SPDs, DC SPDS, Data surge protectors, PoE surge protectors, PCB mounting surge protecors and LED surge protectors, providing comprehensive overvoltage and surge protection solutions for industrial, commercial, and renewable energy systems.
AC Surge Protective Devices are designed to be installed at the service entrance of low voltage systems or close to sensitive equipment to protect against transient overvoltages.
DC surge protective device is isolated DC voltage systems with 600V 1000V 1200V 1500 V DC have a short-circuit current rating up to 1000 A.
Explore FRD2, FRD4, and SRD2 series SPDs for reliable data line protection.
Reliable overvoltage protection secures sensitive equipment across critical infrastructure and data-intensive facilities, helping maintain safety, performance, and continuity.
Overvoltage refers to brief voltage peaks that exceed the rated operating voltage of electrical equipment, often caused by lightning, electrostatic discharges, or switching operations. Without proper overvoltage protection devices, such events can severely damage sensitive systems. Understanding the types and effects of overvoltage is essential for designing effective protection.
Overvoltages can be classified into:
• Internal overvoltage: originating within the system due to faults or switching.
• External overvoltage: resulting from atmospheric discharges such as lightning.
A voltage surge is a sudden rise in excessive voltage between phase-to-phase or phase-to-ground. Surges, whether internal or external, can damage electrical equipment, highlighting the need for reliable surge protection.
Overvoltage protection devices are selected according to the type of load and installation environment, implementing overvoltage protection in three levels:
• Type 1 lightning surge arrester: protects against high-energy surges from lightning.
• Type 2 surge arrester: protects against switching transients.
• Type 3 surge protection device: provides fine protection for sensitive loads.
A building protection system safeguards both structures and electrical installations against direct and indirect lightning strikes. Effective protection involves:
• Capture devices: lightning rods or Faraday cages.
• Down-conductors: safely channel lightning currents to earth.
• Equipotential bonding: links all metallic frames to minimize potential differences that could trigger flashovers.
• Lightning rods: simple or with triggering systems, installed atop buildings and earthed with conductors.
• Faraday cages: multiple symmetrically placed down-conductors protect highly exposed buildings with sensitive equipment.
Even with building protection, 50% of lightning current can enter the installation’s earthing network, generating induced overvoltages. Properly installed SPDs limit these overvoltages to safe levels for electrical and communication systems.
Surge Protective Devices (SPD) are parallel-connected devices in power, telephone, and communication networks. They:
• Divert transient overvoltages to earth.
• Limit amplitude of surges from atmospheric or switching origins.
• Protect switchgear, control gear, and sensitive loads effectively.
After understanding the effects of lightning and the building protection system, selecting the appropriate SPD type and installation location becomes essential. Choosing the right SPD type and placement depends on system configuration, lightning exposure, and the sensitivity of loads, ensuring reliable surge protection.
Proper SPD installation requires both correct connection and optimized cabling to ensure effective overvoltage protection:
• Connection length: Keep SPD conductors as short as possible (<50 cm) to minimize the voltage protection level (Up) at the terminals.
• Conductor cross section:
￮ Normal service: Must carry lightning current with minimal voltage drop.
￮ Short-circuit withstand: Must resist short-circuit currents during maximum cutoff time.
• Feeder separation: Protected outgoing feeders should connect to SPD terminals and remain physically separated from unprotected incoming conductors to prevent coupling.
• Parallel routing: Incoming phase, neutral, and PE conductors should run side by side to reduce loop surface.
• Earthing: Metal enclosures, switchboard frames, and all SPD connections must be earthed via short, direct links.
• Cabling practices:
￮ Pin cables to metallic parts to reduce loop surfaces and benefit from EM shielding.
￮ If shielded cables are used, keep them short to maintain shielding effectiveness.
In PV installations, overvoltage can result from:
• Distribution network fluctuations or maintenance work.
• Direct or nearby lightning strikes on buildings, PV installations, or lightning conductors.
• Lightning-induced variations in the electrical field.
Equipotential bonding should connect all grounded conductors and metal parts to ensure equal potential throughout the PV installation. SPDs are essential to protect sensitive equipment such as AC/DC inverters, monitoring devices, PV modules, and other electrical loads connected to the 230 VAC distribution network.
A Surge Protective Device (SPD) typically consists of:
1. One or more nonlinear components (varistor, gas discharge tube [GDT], etc.) forming the live part.
2. Thermal protection (internal disconnector) to prevent thermal runaway at end-of-life (especially in varistor-based SPDs).
3. End-of-life indicator, sometimes with remote reporting capability.
4. External SCPD for short-circuit protection (may be integrated into the SPD).
Common technologies include:
• Metal oxide varistors (MOV)
• Gas discharge tubes (GDT), controlled or uncontrolled
• TVS diodes
Each has advantages and trade-offs in terms of response time, surge absorption, and reliability.
Indicators inform the user when the SPD is no longer protecting against atmospheric overvoltage.
• Local indication: mechanical or luminous signals connected to the internal disconnector and/or external SCPD.
• Fuse-based SCPD: requires a striker and tripping system.
• Integrated disconnecting breaker: mechanical indicator and control handle provide natural end-of-life signaling.
To ensure these components function correctly and provide reliable protection, installation must comply with international lightning protection standards.
Installation of SPDs should follow IEC 62305 (parts 1–4) for lightning protection:
• Part 1: General principles, lightning characteristics.
• Part 2: Risk management and protection scenario planning.
• Part 3: Protection against physical damage and life hazards.
• Part 4: Electrical/electronic system protection, including SPD selection, cable shielding, and installation rules.
Supplementary standards:
• IEC 61643 series – Surge protection product definitions.
• IEC 60364-4 & -5 – LV installation applications and end-of-life indication requirements.
SPDs installed per these standards ensure reliable overvoltage protection, minimize damage to electrical and electronic systems, and maintain operational continuity.
LSP is a globally trusted manufacturer of overvoltage protection devices, certified by TUV, CB, CE, and ISO 9001. These certifications ensure compliance with IEC/EN 61643-11 and guarantee safe operation worldwide. With these credentials, LSP is a preferred partner for industrial and energy projects requiring reliable surge protection.
Beyond certifications, LSP’s commitment extends to delivering robust and high-performance SPDs for diverse applications.
Every overvoltage protection device from LSP undergoes rigorous quality control to ensure consistent performance and long-term durability. With ISO-certified manufacturing and a global supply chain, these SPDs deliver reliable surge protection across critical industrial and commercial systems, giving engineers and facility managers confidence in protecting sensitive equipment against transient overvoltages.
Our reliable surge protection solutions — proven by real customer success.
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