IEC 60034-15:2009

IEC 60034-15:2009 Overview

IEC 60034-15:2009 is an international standard published by the International Electrotechnical Commission (IEC) that focuses on rotating electrical machines, specifically addressing the impulse voltage withstand levels of form-wound stator coils for rotating alternating current (a.c.) machines. This third edition, released in 2009, replaces the previous 1995 edition with significant updates including clarified scope, removal of voltage limitations, added definitions, and new testing guidance.

This standard defines the test procedures and voltage levels to be applied to both the main and interturn insulation of sample stator coils. The requirements ensure insulation systems in a.c. machines withstand impulse voltages typically encountered during service, improving reliability and safety.

Key improvements in this edition:

• Clearer focus on form-wound stator coils rather than the whole machines.
• Removal of preset voltage limitations, providing flexibility for evolving technology.
• Additional definitions aligning with IEC 60060-1 for clarity.
• Tighter tolerances for steep-fronted impulse voltages.
• Guidance on testing coils used in converter-fed machines.
• Enhanced routines for sample and routine testing, with supporting graphical test examples.

Key Topics Covered

Scope & Application

• Applicable to a.c. machines with form-wound stator coils - coils preformed, insulated, and fully manufactured before installation.
• Addresses testing of both sample coils (representative, fully processed samples) and routine tests applied on all coils.

Impulse Voltage Withstand Levels

• Specifies formulae and voltage levels for impulse withstand tests, including:
  • Lightning impulse voltage withstand for main insulation.
  • Steep-front impulse voltage withstand for interturn insulation.
• Test voltages are based on the machine’s rated voltage with allowances for converter-driven machine conditions (e.g., increased overshoot factors).
• Test wave parameters such as front time and time-to-half-value conform to IEC 60060-1 standards.

Testing Procedures

• Sample Tests: Conducted on at least two fully completed coils, including corona protection layers if present, with coils embedded or wrapped in earthed conductors.
• Interturn Insulation Test: Uses a steep-front impulse voltage generated by capacitor discharge, with strict control on waveform front times and voltage levels.
• Main Insulation Test: Employs lightning impulse voltage typically with a 1.2 µs front time and 50 µs time to half value.
• Routine Tests: Performed on every manufactured coil and complete stator to verify manufacturing consistency and coil integrity.
• Test results are evaluated using oscilloscopes to detect faults such as short circuits or insulation breakdown.

Definitions and Terminology

• Clear definitions of terms like form-wound stator coil, sample test, routine test, front time, and time-to-half value, ensuring standardized understanding.

Practical Applications

IEC 60034-15:2009 is essential for manufacturers, testing laboratories, and engineers involved in the design, production, and quality assurance of a.c. rotating electrical machines. Its practical value includes:

• Ensuring high-voltage insulation robustness in stator coils to withstand transient impulse events such as lightning strikes, switching surges, and converter-induced transients.
• Providing test methods tailored to form-wound coils, which are widely used in medium to large industrial motors and generators.
• Supporting quality control processes during coil manufacturing through well-defined routine and sample tests.
• Informing design engineers about appropriate test voltage levels and waveform characteristics for converter-fed machines, where voltage overshoot can be significant.
• Reducing operational failures and increasing machine longevity by verifying correct insulation withstand capabilities before installation.

Related Standards

IEC 60034-15 integrates with several other international standards for comprehensive electrical machine insulation coordination:

• IEC 60060-1: High-voltage test techniques – Part 1: General definitions and test requirements - provides voltage test waveforms referenced in IEC 60034-15.
• IEC 60034-18-42: Standard for converter-fed AC motors - referenced for adjusting test voltage levels to accommodate voltage overshoots typical in power electronics.
• IEC 60071-1: Insulation co-ordination for equipment within low-voltage systems - offers general insulation level recommendations applicable to rotating machines.
• Other parts of IEC 60034 series detail general machine requirements, testing procedures, and performance characteristics for rotating electrical machines.

By adhering to IEC 60034-15:2009, manufacturers and users of rotating a.c. machines can ensure that form-wound stator coils maintain reliable insulation performance under transient voltage stresses, optimizing machine safety and operational resilience. Proper impulse voltage withstand testing is vital to minimize downtime and enhance the lifetime of electrical machinery in industrial and utility applications.