Standards Development

Scope

This document specifies the general requirements for all Non-linear Metal Oxide Resistors used for surge arresters.

This document is applicable to non-linear metal oxide resistors used in metal oxide surge arresters. It is also applicable when there are no relevant product standards for applications such as independent metal oxide resistor components, integrated non-linear metal oxide resistors, and energy absorption devices employed in high-voltage electrical equipment in power systems.

This document defines the product classification, performance requirements, test types and test methods for non-linear metal oxide resistors.

Purpose

This proposal aims to develop the IEC international standard "General requirements for non-linear metal oxide resistors for surge arresters".

Non-linear metal oxide resistors (i.e., zinc oxide varistors, Metal Oxide Varistor, MOV) are the core components of metal oxide surge arresters. Their performance directly determines the protective characteristics and operational reliability of the arresters. However, the existing series of IEC standards, such as IEC 60099-4 “Surge arresters - Part 4: Metal-oxide surge arresters without gaps for a.c. systems”, IEC 60099-6 “Surge arresters – Metal-oxide surge arresters containing both series and parallel gapped structures – system voltage of 52kV and less”, and IEC 60099-9 “Metal-oxide surge arresters without gaps for HVDC converter stations”, although all specify metal oxide surge arresters with non-linear metal oxide resistors as the subject of standardization, they focus solely on the technical requirements and type tests of the complete arrester, without systematically specifying the product specifications, basic performance parameters, and test methods of the non-linear metal oxide resistor itself — the core component inside the arrester.

The purpose of this standard is to fill the gap in component-level standardization, uniformly specify the key technical parameters and test methods for non-linear metal oxide resistors, including definitions of terms, voltage gradient, charge transfer capacity, residual voltage characteristics, aging performance, and insulation resistance, etc., thereby providing coordinated "component base layer" support for product standards of surge arresters, and enhancing the integrity and technical logical rigor of the IEC surge arrester standard system.

2. Market relevance

2.1 Global market scale and growth trend

Non-linear metal oxide resistors, as core protection components in power system overvoltage protection, electronic device surge suppression, and new energy power conversion, are widely applied across a broad range of fields, including power systems, rail transportation, renewable energy generation, communication base stations, new energy vehicles, and consumer electronics, covering an extremely extensive market with continuously growing global demand.

2.2 Urgent Needs for Technological and Industrial Development

Currently, non-linear metal oxide resistors technology is rapidly advancing toward higher voltage gradients, lower residual voltages, higher energy absorption capability, and universal applicability for both AC and DC systems. The construction of new power systems, such as UHV AC/DC transmission, flexible DC transmission, and renewable energy grid integration, imposes higher protection performance requirements on surge arresters, directly driving the improvement of performance indicators for non-linear metal oxide resistors. Factors, such as resistor dimension design, material formulation, and interface processes, directly affect the protection level and operational reliability of the complete arrester. Existing industry studies indicate that common technical challenges remain with respect to the high-current impulse withstand capability of resistor. Therefore, the development of a component-level standard is necessary to optimize test methods, harmonize pass/fail criteria, and enhance process control.

2.3 Broad Coverage of Stakeholders

The development of this standard will benefit the following stakeholder groups:

Surge arrester manufacturers – by providing uniform and reliable criteria for component procurement and acceptance;

Specialized manufacturers of non-linear metal oxide resistors – by defining clear product performance classifications and test methods, thereby facilitating technological innovation and access to international markets;

Power system operation and maintenance entities – by enhancing the overall reliability of surge arresters, thereby strengthening the security assurance of grid operation;

Third-party testing and certification bodies – by obtaining standardized test criteria at the component level;

and

Relevant research institutions and universities – by guiding technology R&D directions through standardization. 

2.4 Global Relevance and Basis for International Consensus

The Non-linear Metal Oxide Resistor technology addressed in this standard has been widely adopted worldwide, and its technical foundation enjoys extensive international consensus. IEC TC 37 (Surge Arresters) has long been dedicated to the standardization of high-voltage surge arresters, and the IEC 60099 series standards are universally recognized and implemented across the global power industry.

This proposal has undergone preliminary communication with technical experts from relevant member countries within the IEC TC 37 framework, receiving positive feedback. It is expected to garner active support and expert participation from P-members of many countries.

3. Whether this proposal constitutes a horizontal standard

This proposal is not submitted as a horizontal (generic/cross-sector) standard.