IEC 61643-32:2017

Overview

IEC 61643-32:2017 is an international standard published by the International Electrotechnical Commission (IEC) that establishes the principles for selecting and applying low-voltage surge protective devices (SPDs) specifically designed for photovoltaic (PV) installations. The standard covers SPDs connected to the direct current (d.c.) side of PV systems with voltages up to 1,500 V DC, as well as the alternating current (AC) side rated up to 1,000 V rms at 50/60 Hz.

This standard is essential for ensuring the protection and reliability of PV systems by detailing the methods for installation, coordination, and maintenance of surge protection devices in various PV environments, including rooftop installations and ground-mounted free-field power plants. IEC 61643-32:2017 is updated to include corrigenda from June 2019, reflecting the latest consensus on practices and technology.

Key Topics

• Scope of PV Installations: Covers full photovoltaic installations-from PV arrays and interconnected modules to inverters and utility connection points.
• Types of PV Systems: Includes both rooftop systems and free-field, multi-earthed power plants on the ground, with special considerations for each.
• Surge Overvoltages: Identifies typical overvoltage scenarios in PV systems and the need for effective surge mitigation.
• Installation Practices: Specifies the correct placement and connection of SPDs on DC and AC sides to maximize protection.
• SPD Selection: Criteria for choosing SPDs, including:
  • Nominal discharge current (I n)
  • Impulse current (I imp)
  • Voltage protection level (U p)
• Coordination of Devices: Guidance on protecting different parts of the PV installation by coordinating multiple SPDs to ensure effective surge energy management.
• Equipotential Bonding: Requirements for equipotential bonding to reduce electrical potential differences and improve safety.
• Maintenance: Recommendations for ongoing inspection, testing, and replacement of SPDs to sustain system integrity.

Applications

IEC 61643-32:2017 is crucial for a variety of stakeholders in the photovoltaic industry, including:

• System Designers and Engineers: Enabling sound decision-making when selecting and positioning surge protective devices for PV systems.
• Installers and Contractors: Providing practical instructions on how to apply SPDs correctly on both DC and AC sides of PV installations.
• Facility Managers: Offering maintenance protocols to extend equipment life and prevent costly system downtime caused by surge damage.
• Manufacturers and Suppliers: Assisting in the design and certification of SPDs tailored for PV applications, ensuring compliance with international safety and performance standards.
• Utility Providers: Ensuring that PV installations connected to the grid operate safely under transient overvoltage conditions.

This standard is especially important in environments with high exposure to lightning strikes or switching surges, common in both rooftop and large-scale solar power plants.

Related Standards

IEC 61643-32:2017 is part of a broader suite of international standards that address surge protection and photovoltaic system safety:

• IEC 61643 Series: Covers low-voltage surge protective devices for various electrical installations and equipment.
• IEC 61730: Safety requirements for photovoltaic modules.
• IEC 62109: Safety of power converters used in PV systems.
• IEC 60364: Electrical installations of buildings, including grounding and protection against electric shock.
• ISO/IEC 60721: Classification of environmental conditions, useful for assessing SPD suitability in different climates.

Compliance with IEC 61643-32:2017 in conjunction with related standards ensures comprehensive protection of photovoltaic installations against surge-related risks while meeting global safety norms.

Keywords: IEC 61643-32, surge protective devices, photovoltaic installations, PV system protection, low-voltage SPD, DC side surge protection, PV power plant safety, SPD selection, PV inverter protection, IEC surge protection standard.