Partial Discharge (PD) Measurement

1. IEC 62478A Prospective Standard forAcoustic and ElectromagneticPartial Discharge MeasurementsMichael MuhrUniv.-Prof. Dipl.-Ing. Dr.techn. Dr.h.c.Institute of High Voltage Engineering and System Management University of Technology Graz

2. Sensitive nondestructive method as important diagnostic tool for evaluation of the insulation condition PD-defect Location and Detection Partial Discharge (PD) Measurement Non electrical methods Electrical M. Muhr

3. Macroscopic-Physical Effects Detection Methods Optical Effects(Light) Optical Acoustic HV Pressure Wave(Sound) Mechanical Opto-acoustic Discharge EffectsDielectric LossesHigh Frequency Waves Electrical IEC 60270 HF/VHF/UHF Chemical Effects Chemical Heat Partial Discharge Measurement M. Muhr

4. ZFilter Test object Coupling capacitor HVmeasure PD Pulse G PD-System HV-Source Quadripole Measuring impedance PD-Detection Methods IEC 60270 • Conventional electrical measurement • Integration at frequency domain Narrow-band Wide-band • Integration at time domain M. Muhr

5. Acoustic HV - Chemical - Optical PD Directional microphone PD-Detection Methods • Electrical measurements with high frequencies • HF / VHF method – 3 MHz to 300 MHz • UHF method – 300 MHz to 3 GHz • Acoustic measurements – 10 kHz to 300 kHz • Optical measurements – ultraviolet – visible – infrared range • Chemical measurements M. Muhr

6. Light produced during the discharge Eye Optical sensor Low-light enhancer Fiber-optic cable Infrared camera Coronascope Optical detection and localisation Outside not accessible: - Fibre-optic cable - Collimator - Photodiodes • Outside accessible: • Eye • Low-light amplifier • - Coronascope Optical – PD-Measurement M. Muhr

7. Peak Rd Voltage supply Lens M Optical fibre CC LWL Signal- conversion ST PR W optical system Medium oil VP Optical fibre with lens Observation area conventional opt. fibre Peak PC IEC 270 Oscilloscope, ADU fluorescent opt. fibre Measuring circuit after IEC 60270 and optical measuring system Plate Fluorescent optical fibre PD – Optical Detection M. Muhr

8. Photomultiplier I/U Oscilloscope SF6 ADU Conv. PD Detector Optical – PD-Detection in GIS Emission spectrum of corona discharges in SF6 Test arrangement for optical PD-measurement M. Muhr

9. Arc Partial discharge Higher temperatures fluoric compounds (Fluoride) Sulfur-compounds (Sulfate, Sulfide) SF6 decomposition Sulfur- fluoric-compounds Chemical – PD-Measurement Sensors and analyser • H2 Sensor • DGA (Gas in oil analysis) • Ozone analysis • Gas Analysis M. Muhr

10. IEC DGA Gas ratio values Chemical – PD-Measurement M. Muhr

11. HF / VHF – PD-Measurement HF / VHF – Partial Discharge Detection • Frequency range 3 MHz to 300 MHz • HF 3 – 30 MHz • VHF 30 – 300 MHz • Measuring systems • Narrow-band, band width < 2 MHz • Wide-band, band width > 50 MHz • Sensors • Capacitive, inductive, electromagnetic M. Muhr

12. Rogowski coil PD Analyser HF / VHF – PD-Measurement Rogowski coil Measuring for HF – PD-detection on machines, VHF – PD-coupler, Split ring Rogowski coil M. Muhr

13. 1 2 3 direct. coupling A B direct. coupling C D Principle of the coupler sensor HF / VHF – PD-Measurement M. Muhr

14. A LDP-5 B C-Sensor HF / VHF – PD-Signal Damping Damping effects: • Geometric proportions • Discontinuities • Impulse form • Refraction • Reflection • Frequency • Material M. Muhr

15. UHF – PD-Measurement UHF – Partial Discharge Detection • Transient electromagnetic waves • Frequency range 300 MHz to 3 GHz • Narrow band (~ 5 MHz) • Wide band (~ 2 GHz) • Propagation : - TM Wave (Transversal magnetic wave) - TE Wave (Transversal electric wave) - TEM Wave • Not coupled to the conductor M. Muhr

16. Narrow band Wide band PRPD pattern low-pass filter PD measuring instrument amplifiers Spectrum analyser Peak detector UHF – PD-Measurement UHF – PD-measurement M. Muhr

17. Detector Dectector Conductor Conductor Cage Cage • - Mobile • UHF-window • sensor • Conventional • UHF-sensors • Disc sensor • Cone sensor Field grading electrodes UHF – PD-Sensors M. Muhr

18. UHF measurement Signal 1 C1 C2 Defect Impulses of variable amplitude PG UHF measurement Signal 2 C1 C2 Sensitivity Verification M. Muhr

19. L1 L2 1 Defect Amplitude 2 Sensor 2 Sensor 1 Measuring instrument Zeit Pre amplifier Time delay Schematic arrangement 1 ... Sensor 1 2 ... Sensor 2 UHF – PD-Fault Location M. Muhr

20. Sensitivity of developed UHF-sensors UHF – PD-Signal Damping, Sensitivity Damping effects: • Frequency • Geometries • Conductor material • Mode type • Reflection and refraction Sensivity: • Facility configuration • Failure location • Location of the sensor • Measurement equipment M. Muhr

21. Acoustic – PD-Measurement Acoustic Partial Discharge Detection • Acoustic signal as a result of the pressure wave produced by PD • Frequency spectrum 10 Hz up to 300 kHz SF6 Box AE Sensor Air Principle schematic to the acoustic PD-detection M. Muhr

22. - Piezo-electric (sound emission) - Condenser microphones • Structure-born sound-resonance - Accelerometer • Opto-acoustic-sensor HV PD HV Sensor PD Directional microphone Signal Time delay Time Acoustic – PD-Sensors M. Muhr

23. Oscilloscope Acoustic – PD-Measurement PD-Detector AE Sensor amplifier Filter A/D Converter Acoustic – PD-detection system M. Muhr

24. Acoustic fingerprint of a overhead line conductor Acoustic – PD-Measurement Damping effects: • Equipment dispersion • Construction • Insulation structures • Gas pressure • Encapsulation material • Absorption during a medium to another • Geometrical spreading of the wave M. Muhr

25. Reference optical fibre coil Laser Beam Splitter Beam Splitter Detector Oil tank High Voltage Sensing optical fibre coil PD-source Opto-Acoustic – PD-Measurement Experimental setup of the optical interferometric detection of PD M. Muhr

26. IEC TC42 WG 14 Content 1 • Scope • Phenomena • PD occurrence in discharging defects • Frequency / time behaviour • Specifies of HV-components • Applicability for detection • Normative References • Definitions • Sensors • Types, parameters, positioning • Location (time and frequency domain) vs measurement only M. Muhr

27. IEC TC42 WG 14 Content 2 • Transmission Aspects A) UHF Aspects • PD source, quantity E [V/m]spectrum, filed mode, signal strength, magnitude, characteristic impedance, velocity of medium, distance, activity • Sensor-antenna, basic quantity [m]type, bandwidth, position, receiving area, transfer impedance, characteristics • Reading quantity [V] • Derived quantitymeasuring equipment, bandwidth, center frequency, tuning M. Muhr

28. IEC TC42 WG 14 Content 3 B) HF / VHF Aspects • PD source, quantity [V] or [A]electric or magnetic signal, impedance, signal magnitude, distance, activity • Sensor – impedance [R, L, C]type, bandwidth, position, dielectric attenuation, distortion, polarity aspects • Reading quantity [V, A] • Derived quantitymeasuring equipment, center frequency, tuning, bandwidth, pulse resolution M. Muhr

29. IEC TC42 WG 14 Content 4 C) Acoustic Aspects • Mechanical pressure, quantity [Pascal]pressure waves, modes, acoustic impedance, delay, propagation velocity, distance • Sensor – impedancepiezo electric, composite material, optical, microphone, directivity, position, coupling, bandwidth, linearity • Reading quantity [V] • Derived quantitymeasuring equipment, pulse counter, pulse pattern M. Muhr

30. IEC TC42 WG 14 Content 5 • System Checks Performance and sensitivity check • UHF Aspectsperformance check: functional check of the whole measuring path including sensor and PD acquisition systemsensitivity check: emission of electromagnetic waves into test objects, distance • HF / VHF Aspectsperformance check: sensor to sensor coupling in a specific arrangementsensitivity check: injection of field signal to test object, distance • Acoustic Aspectsperformance and sensitivity check: recommendation of acoustic standards M. Muhr

31. IEC TC42 WG 14 Content 6 • pC Correlation • HF / VHF / UHF – pulse generator injection to determine relation between pC and measured quantities • Acoustic: can not compared to pC without knowing the type of PD source • New quantities • parameters linear with sensor output [mV] • parameters quadratic with sensor output [mW] • effective height [mm] – ratio between sensor output and incoming electrical field • Effective aperture [mm2] – ratio between maximum sensor output power and power density of incoming electrical field • sensor gain [dBi] – ratio between receiving power antenna and receiving power of isotropic radiator M. Muhr

32. EM – PD Source Basic Quantity E [Volt / meter] Sensor – Antenna Basic Quantity e.g. [meter] Physical Generic Aspect Reading Quantity [Volt] Low Standard Deviation Definition of Transfer Characteristic Mathematical Term Quantity [m Watt] Quantity [Volt] PD [pC] High Standard Deviation System Check PD [pC] Low Standard Deviation Definition of Transfer Characteristic IEC TC42 WG 14 Content 7 M. Muhr

33. IEC TC42 WG 14 Content 8 Non Standardization • Applicable sensor • Test and measuring configurations • Interpretation – task of the component panels M. Muhr

34. Thank You for Your Attention Thank You for Your Attention M. Muhr