Overview
IEC TS 60034-27-5:2021 specifies an off-line measurement method for partial discharge inception voltage (PDIV) and partial discharge extinction voltage (PDEV) on winding insulation of rotating electrical machines when exposed to repetitive impulse voltage. The Technical Specification focuses on test methods, measurement circuits and procedures relevant to machines that can be supplied by a voltage source converter (VSC). It complements the IEC 60034 series by addressing impulse-type stress and the measurement of PD under pulsed waveforms.
Key Topics and Requirements
- Scope and terminology: definitions, symbols and abbreviated terms used for impulse PD testing of rotating machines.
- Repetitive impulse voltages: characteristics of single impulses, typical waveform distortions at the test object, trains of impulses and stepped-by-step (SBS) voltage increase/decrease patterns used for PDIV/RPDEV measurement.
- Impulse waveform considerations: rise time, peak, overshoot, ringing and slow oscillation effects as they appear at the generator and at winding terminals.
- Measurement methods: electrical PD detection with coupling capacitors, HF current transformers (HFCT), electromagnetic or UHF couplers and required analogue filtering to suppress supply impulses.
- Detection threshold and data handling: recommendations on PD detection threshold, noise suppression and use of a PC-based measuring system to calculate RPDIV (repetitive PD inception voltage) and RPDEV.
- Test objects and connections: guidance for testing twisted-pair samples, motorettes/formettes and complete windings including three- and four-terminal connection schemes.
- Test procedure and safety: conditioning procedures, grounding/floating practices, environmental considerations and reporting requirements.
- Illustrative materials: block diagrams, impulse patterns, example connection schemes and annexes with typical PD data analysis and test parameter tables.
Applications
This specification is intended for:
- Manufacturers of motors and generators for end-of-line and type testing of winding insulation against repetitive impulse stresses.
- Testing and diagnostic laboratories performing off-line PD measurements and acceptance tests.
- Service engineers and condition-monitoring teams assessing insulation integrity following converter-fed operation or prior to service.
- R&D teams developing VSC-driven machines or insulation systems subject to repetitive impulse stress.
Practical uses include acceptance testing, insulation qualification, failure analysis and research into PD behaviour under converter-related impulse waveforms.
Related Standards
- IEC 60034 series (rotating electrical machines)
- IEC TS 61934:2011 (referenced in PD analysis examples)
- Other IEC documents on PD measurement and high-voltage testing (see normative references in IEC TS 60034-27-5:2021)
Keywords: IEC TS 60034-27-5:2021, partial discharge, PD inception voltage, repetitive impulse voltage, winding insulation, rotating electrical machines, voltage source converter, off-line PD measurement, RPDIV, RPDEV.