IEC 60034-15:2025

Overview

IEC 60034-15:2025 (Rotating electrical machines - Part 15: Impulse voltage withstand levels of form-wound stator coils for rotating a.c. machines) specifies the impulse voltage withstand requirements for form-wound stator coils used in rotating AC machines connected to a standard grid supply. Developed by the International Electrotechnical Commission (IEC), this standard addresses test procedures and voltage levels for verifying the resilience of stator coil insulation against voltage transients originating from the power grid. Specifically, this standard excludes stator windings and coils for converter-fed machines and is not intended for complete winding assemblies due to practical limitations in assessing insulation failure points.

With updated test levels to harmonize with IEEE Std 522, enhanced surge impulse levels, and improved test evaluation guidance, IEC 60034-15:2025 aims to ensure the electrical reliability of industrial AC machines, reducing premature failure and maintenance costs due to insulation breakdown.

Key Topics

• Scope of Application: The standard focuses on form-wound stator coils in AC machines meant for grid supply, excluding coils for converter-fed machines.
• Test Procedures and Voltage Levels: It defines standard and enhanced impulse voltage withstand test levels, including both lightning impulse (SLI) and steep-front impulse (SFI) types.
• Sample and Routine Tests: Procedures cover both sample tests on individual coils and routine tests on coils within the stator core, ensuring quality during manufacturing.
• Oscillation and Overshoot Evaluation: Guidance is included for evaluating test impulses where oscillations or voltage overshoot are present.
• Harmonization and Updates: The 2025 edition has harmonized test levels with IEEE Std 522, introduced higher withstand thresholds and additional testing options, and clarified exclusions for converter-fed machines.

Applications

IEC 60034-15:2025 is essential for machine manufacturers, electrical engineers, and quality assurance teams involved with:

• Design and Manufacturing: Ensuring that form-wound stator coils have adequate surge withstand capability for grid-connected AC machines (such as generators and large motors).
• Testing and Commissioning: Defining the impulse voltage withstand tests needed during production and before commissioning to minimize risk from switching surges, lightning strikes, or other grid-originating transients.
• Maintenance and Reliability: Supporting periodic assessment methods to verify ongoing insulation integrity and reduce unplanned equipment downtime.
• Procurement Specifications: Offering clearly defined impulse test requirements for purchase contracts between users and manufacturers, particularly for industries with stringent reliability demands (e.g., power generation, industrial motor drives).

Practical use of the standard helps in extending the service life of rotating electrical machines, maintains operational safety, and enables compliance with both local and global product safety regulations.

Related Standards

Organizations adopting IEC 60034-15:2025 should also consider the following related standards:

• IEC 60060-1: High-voltage test techniques - General definitions and test requirements, referenced for impulse generation and measurement methods.
• IEC 60034-1: Rotating electrical machines - Part 1: Rating and performance, the principal standard for rotating machines.
• IEC 60071-1: Insulation co-ordination - Part 1: Definitions, principles, and rules, providing background on insulation requirements.
• IEEE Std 522: Guide for testing turn insulation of form-wound stator coils for alternating-current rotating electrical machines, harmonized with the impulse withstand levels in this IEC edition.

By aligning with these standards, manufacturers and end users can ensure robust insulation performance in grid-connected rotating machines, supporting both safety and reliability across diverse industrial applications.

Keywords: IEC 60034-15, impulse voltage withstand, form-wound stator coils, surge testing, rotating electrical machines, grid-connected motors, insulation reliability, SLI test, SFI test, AC machine standards, oscillation and overshoot in high-voltage tests.