IEC 61643-31:2018

Overview

IEC 61643-31:2018 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the requirements and test methods for low-voltage Surge Protective Devices (SPDs) used in photovoltaic (PV) installations. This standard applies specifically to SPDs designed for installation on the DC side of photovoltaic systems rated up to 1,500 V DC. These SPDs provide protection against both the direct and indirect effects of lightning and transient overvoltages, ensuring the safety and longevity of PV installations.

The standard defines performance characteristics, safety criteria, and test procedures for SPDs intended to limit surge voltages and divert surge currents. Only SPDs that are permanently connected and installed on the DC side of PV modules or inverters are covered, excluding portable devices and systems with integrated energy storage such as batteries or capacitor banks.

Key Topics

• Scope and Application
  IEC 61643-31:2018 targets surge protective devices installed on the DC side of photovoltaic generators and inverters. It excludes SPDs designed for PV systems with energy storage and two-port SPDs containing series impedance.

• SPD Design and Classification
  The standard classifies SPDs based on design types and protective functions, as well as installation location criteria (indoor versus outdoor), accessibility, and earthing systems. It outlines features for one-port SPDs and multipole devices, including failure modes and environmental suitability.

• Electrical and Mechanical Requirements
  The document stipulates strict electrical parameters such as voltage protection level, residual current, continuous current capability, insulation resistance, and dielectric withstand voltage. Mechanical requirements include mounting, connection integrity, air clearances, creepage distances, and overall mechanical strength.

• Environmental and Material Criteria
  SPDs must endure various service conditions, including wide temperature ranges, humidity, and electromagnetic compatibility. The standard mandates testing under damp heat and other environmental stresses to guarantee reliability in PV operational environments.

• Testing Methods
  Detailed test protocols are described, comprising type tests, routine tests, and acceptance tests. These include operating duty tests, failure mode behavior assessment, dielectric withstand tests, and electromechanical verification under transient conditions typical for PV applications.

Applications

The IEC 61643-31 standard is crucial for manufacturers, installers, and specifiers working with photovoltaic systems to ensure:

• Surge Protection in Solar Farms and Rooftop PV Arrays
  Properly rated SPDs minimize damage from lightning-induced surges and switching transients, protecting expensive solar panels and inverters.

• Reliability and Safety of DC-Side Electrical Components
  Compliance with this standard ensures that surge devices maintain operational integrity, preventing fire hazards and equipment failures.

• Optimized System Performance
  By limiting transient overvoltages, SPDs that meet this standard help maintain system stability and prolong the lifespan of PV installations.

• Standardized Quality Assurance
  The defined test methods enable quality control and certification, facilitating global market access for compliant surge protective devices tailored to photovoltaic applications.

Related Standards

• IEC 61643-11 - General requirements for SPDs in low-voltage electrical installations, providing a broader context for surge protection beyond photovoltaic systems.

• IEC 60529 - Defines IP codes related to degrees of protection of enclosures that may apply to SPD enclosures per IEC 61643-31 requirements for environmental resistance.

• IEC 60068 - Environmental testing procedures that supplement the durability and robustness requirements outlined in IEC 61643-31.

• IEC 62446 - Standard for grid-connected photovoltaic systems, addressing the integration aspects that SPDs protect against transient surges.

By following IEC 61643-31:2018, stakeholders in the solar industry can ensure that photovoltaic systems are equipped with surge protection devices that meet internationally recognized safety and performance benchmarks, enhancing system reliability and reducing downtime caused by surge-related damages.