IEC 60085:2007

Overview

IEC 60085:2007, Electrical Insulation – Thermal Evaluation and Designation, is a key international standard published by the International Electrotechnical Commission (IEC). This standard sets out the framework for distinguishing and evaluating thermal classes applicable to electrical insulation systems (EIS) and electrical insulating materials (EIM). It provides standardized criteria for assessing the thermal endurance of insulating materials and systems, as well as procedures for assigning appropriate thermal classes. IEC 60085:2007 is particularly relevant when thermal stress is the principal ageing factor impacting the reliability and lifespan of electrotechnical devices.

Key Topics

• Thermal Classes for Insulation Systems and Materials
  • Distinguishes between the thermal class of an EIS and the thermal endurance of individual EIMs.
  • Establishes that the thermal class of an EIS is not necessarily equal to the endurance of its components.
• Criteria for Thermal Endurance Evaluation
  • Provides the methodology to evaluate thermal ageing, using reference and candidate materials or systems.
  • Emphasizes that thermal evaluation should follow recognized procedures specified in the standard.
• Assignment of Thermal Classes
  • Defines thermal classes based on service experience or results of functional tests.
  • Sets numerical values (in Celsius) for maximum recommended continuous operating temperatures.
• System vs. Material Approach
  • Clarifies that the designation of a thermal class to an EIS does not imply that all constituent EIMs are of the same class.
  • Notes the interactions between materials within a system, which can impact overall thermal performance.
• Applicability
  • Applies when the thermal factor is the main driver of ageing in electrical insulation.
  • Recognizes that other factors (mechanical stress, chemicals, moisture, etc.) must also be considered.

Applications

IEC 60085:2007 is widely used across industries where electrical insulation plays a crucial role in safety, durability, and efficiency, including:

• Rotating Machines and Motors: Defining the suitable thermal class for insulation systems to maximize motor lifespan and reliability.
• Transformers: Specifying insulation requirements to ensure safe operation under continuous thermal stress.
• Cables and Windings: Assigning appropriate thermal classes to insulation to meet performance and safety standards.
• Electrical and Electronic Equipment: Ensuring that insulating materials and systems are capable of withstanding expected maximum service temperatures.
• Product Testing and Certification: Used by manufacturers, laboratories, and certifying bodies to standardize evaluation methods for thermal performance.

By referencing IEC 60085, engineers and manufacturers can ensure compliance with international best practices, reduce equipment failure risks, and improve product marketability.

Related Standards

IEC 60085:2007 incorporates and refers to several related IEC standards, essential for comprehensive thermal evaluation of electrical insulation. These include:

• IEC 60216 Series: Methods to determine the thermal endurance of insulating materials.
• IEC 60505: Guidance on the evaluation and qualification of electrical insulation systems.
• IEC 61857 Series: Procedures for thermal evaluation of electrical insulation systems, particularly for wire-wound applications.
• IEC 61858: Evaluation procedures for modifications to established EIS.
• IEC 62114: Previously a separate standard, now merged to streamline assessment methodologies.

These interrelated standards collectively form the backbone of global best practices for the thermal evaluation and designation of electrical insulation systems and materials.

Keywords: IEC 60085, electrical insulation, thermal evaluation, insulation system, insulation material, thermal class, endurance, electrotechnical, standards, maximum operating temperature.