This document provides an overview of partial discharge training. It begins by defining what partial discharge is and discussing some of the common causes. It then explains how partial discharge is measured, including through transient earth voltage detection and ultrasonic detection. Various types of partial discharge are described, including internal discharges occurring within insulation cavities and surface discharges at insulation boundaries. Examples of partial discharge findings from switchgear components like cable terminations and circuit breakers are shown. The document also discusses partial discharge instrumentation and the analysis and reporting of partial discharge measurement results.

1. Partial Discharge Training

2. • Apa itu Partial Discharge ?
• Apa penyebab Partial Discharge ?
• Bagaimana Mengukur Partial Discharge?

3. Question ....
Apa saja tipe Isolasi yang kemungkinan ada di
dalam switchgear ???

4. Dielectric Strength
Material Dielectric Strength
Air ~3 kV/mm
Mineral Oil ~10- 15 kV/mm
Polyethylene ~20 kV/mm
EPR (Rubber) ~25 kV/mm
Vacuum ~20-40 kV/mm
Impregnated Paper ~20-50 kV/mm
XLPE ~20 kV/mm
SF6 (3.5 bar) ~15 kV/mm

5. Partial Discharge Activity
• Gaseous medium
• Voids or gaps
• Electrical stress
• Elektron
e¯
e¯
e¯
e¯

6. Teori ....
• Bagaimana sebenarnya Partial Discharge itu
terjadi ???!!
Partial discharge terjadi ketika electrical stress
melebihi 3kV/mm

7. Discharge in Gas ...
• Untuk medan listrik homogen antara dua
elektroda
• Jika E cukup tinggi : akan dimulai dengan ionisasi
 Elektron akan lebih cepat dan bertabrakan dengan
molekul
 Jika kecepatanya cukup cepat : ionisasi akan berlanjut
karena energi kinetik dari elektron
 Terjadi reaksi berantai: gas menjadi plasma, maka
aka terjadi thermo-ionisasi
 Lalu akan timbul percikan yang mengakibatkan
breakdown

8. Electrical field
• Untuk medan listrik non-homogen: E tinggi di
ujung, rendah pada plate
• PD dimulai jika E lebih tinggi daripada E critical
• Perilaku PD tergantung pada E:
– Voltage level dan ukuran

10. Partial Discharge adalah .....
peristiwa pelepasan/ loncatan bunga api listrik
yang terjadi pada suatu bagian isolasi (pada
rongga dalam atau permukaan) sebagai akibat
adanya beda potensial yang tinggi dalam isolasi
tersebut.

11. Why Test
• Safety
• Loss of Supply
• Asset Management

12. Analysis of MV Switchgear Faults
Ea Technology, 2006

13. Common Discharging Components
Component % age of Sources
Cable Box 36 %
Circuit Breaker 25%
Voltage Transformer 20%
Busbar 10%
CT Chamber 9%
General figures based on large database of results primarily on 11kV switchgear

14. Types of Switchgear
• 3.3kV to 66kV
• Indoor Metalclad extensible switchboards
• Indoor and Outdoor Ring Main Units

15. PD Clasification
• Internal Discharges: occuring in cavities within solid or liquid
dielectrics
• Surface Discharges: appearing at the boundary of the
different insulation materials
Continuous impact of discharges in solid dielectrics
forming discharge channels (treeing) in organic materials
Corona discharge occuring in gaseous dielectrics in the
presence of inhomogeneous fields

16. PD Classification

17. So Why ??
PD occur
Electromagnetic
Radio Light Heat
Acoustic
Audio Ultrasonic
Gases
Ozone Nitrous Oxides

18. Partial Discharge
• Surface Discharge
• Internal Discharge

19. Internal Discharge
(TEV Detection)
• High Frequency transient
signals from discharge
sources
• Travel over switchgear
surfaces
• Detected using capacitively
coupled probes on
switchgear metalwork

20. Apa TEV itu sebenarnya ??
• Transient : lasting only for a short time; impermanent
Jadi TEV bisa dikatakan tegangan yang muncul dalam
waktu yang singkat menuju ground.

21. Internal Partial Discharge

22. Internal Partial Discharge

23. Transient Earth Voltage (TEVs)
TEV (mV) dB
1 0
1.12 1
1.78 5
3.16 10
10 20
31.6 30
100 40
316 50
1000 60
1410 63
http://www.naval.com/help/db-x.htm

24. Internal Discharges (TEV)
• Internal discharge activity
Trainsient Earth Voltage (TEV) Detection
High Frequency (~ 3 to 80 MHz)
• TEV magnitude is function of
 The amplitude of the discharges
 The attenuation of the propagation path

25. Example Internal Discharge
• 11kV Cast Resin CTs
Long term erosion of insulation
leading to flashover and failure

26. Example Internal Discharge
• Overhead Cable Termiantion

27. Example Internal Discharge
• Cable termiantion screen termination

28. Surface Discharge
(Ultrasonic Detection)
• In severe cases, sound may be
audible
• Less severe deterioration may be
detected using ultrasonic
detecting instruments
• Sound spectrum includes 40 Khz
• Primarily spot check
measurements although extended
monitoring is possible

29. Surface Discharge Activity
• Discharge across
surface of insulation
towards earth or
phase to phase
discharge
• Often characterised
by low amplitude but
very high discharge
rate

30. Surface Discharge Activity Detected by
Ultrasonics

31. Surface Discharge on 11kV Cast Resin
Circuit Breaker Spouts

32. Surface Discharge Activity Detected by
Ultrasonics

33. Contamination make a Surface PD

34. Moisture Ingress leading to surface
tracking

35. Oil degradation leading surface
erosion of insulation

36. Corrosion due to PD activity
1. Greening of fuse caps
2. Rusting of securing bolts
3. Tracking along the glass reinforced
Plastic fuse bar
1
2
3

38. TEV Background Interference
Mobile
Phone
Mast
HV OHL
Variable speed
drive
DC Light fitting
Radio Mast
Battery
Charger

39. Possible Ultrasonic Background
Interference

40. Practical Non- Intrusive Detection
Methods
• Internal discharge activity
 Transient Earth Voltage
 High Frequency (~ 3 to 80 MHz)
• Surface discharge activity
 Ultrasonic Emission ~ 40 kHz
 TEV Detection – when high amplitude surface discharge

41. PD Instruments

42. UltraTEV Detector

43. UltraTEV Detector
• Ideal for first pass surveys of surface and
internal PD activity

44. UltraTEV Detector
• TRAFFIC LIGHT display indicates PD levels

45. UltraTEV Detector
• ESSENTIAL personal safety device

46. UltraTEV Plus+

47. UltraTEV Plus+
• Quickly locates & mesures surface and
internal PD activity

48. UltraTEV Plus+
• INSTANTLY reveals the condition of assets

49. UltraTEV Plus+
• PLUG-IN OPTIONS for added versatility

50. TEV Functions
• Two TEV display options
• Display with rolling bar graph
indication and traffic light
alarm level indication
• Display with amplitude,
pulses per cycle and severity
values

51. Ultrasonic Measurements
• Measurement of surface discharge
activity in range
 7dBµV to 68dBµV
• 40kHz sounds heterodyned to audioble
output with high quality headphones
• External Ultrasonic sensor port
• User adjustable alarm thresholds
 Preset to UltraTEV Detector levels

52. Ultrasonic Features
• Separately adjustable Gain
and Volume settings
• Immediate Red/Green
indication based on user
adjustable alarm threshold

53. PD Locator
• Measures the amplitude of discharge in dBmV
• Locates source of discharge through precedence
detections using both probes, resolution 2ns,
0.6m
• Procedure
Measure background noise
Survey with one probe only
Source internal if reading on switchgear > 10dB above
background noise
Locate using 2 probes

54. UltraTEV Locator

55. UltraTEV Locator
• SURVEYS & LOCATES PD activity in all
substation assets – including cables

56. UltraTEV Locator
• MEASURES & RECORDS PD activity in all
substation assets – including cables

57. UltraTEV Locator
• PLUG-IN OPTIONS for greater versatility

58. PD Location

59. Reporting and Analysis of Results

60. Assessment of Partial Discharge
Activity in Switchboard
• Partial Discharge Locator (PDL) survey
• Ultrasonic survey of any air insulated
components
• Monitor for one week with Partial Discharge
Monitor (PDM)
• Analyse results against historical information

61. Interpretation of results
• Investigate previous failures
• Is there a common failure mode
• Check previous results
 Same switchboard
 Similar switchboards
• Compare against specific information
• Compare against general information

62. Analysis Considerations
• Maximum Level of Partial Discharge
• Maximum Short Term Severity
• Long Term Severity
• Working Voltage
• Equipment component
• History of failures, if any
• Circuit importance

63. Partial Discharge Severity Calculations

65. Terimakasih ......