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PD Test Experience

The document discusses on-site partial discharge (PD) testing in Thailand, highlighting practical issues such as environmental noise and PD signal attenuation. It details characteristics of internal PD, various testing systems, and expected results, alongside examples of cable failures. The document emphasizes the importance of understanding PD inception and extinction voltages in relation to operational voltage.

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asawinraja
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127 views23 pages

PD Test Experience

The document discusses on-site partial discharge (PD) testing in Thailand, highlighting practical issues such as environmental noise and PD signal attenuation. It details characteristics of internal PD, various testing systems, and expected results, alongside examples of cable failures. The document emphasizes the importance of understanding PD inception and extinction voltages in relation to operational voltage.

Uploaded by

asawinraja
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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On-site PD Test:

Thailand Experiences
Presentation Topics

PD aspects

Onsite offline PD measurement

Practical issues
Defects in Cable

1. interface gap formation


2. cavities
3. cavities eventually with conductive sharp points

[Source: PD in Electrical Power Apparatus; ISBN 3-8007-1760-3]


Characteristics of Internal PD

A
Ut(t)
U1(t)
2CS
er
CP/2 CF e0 CP/2 Uz
UL
2CS -UL t
U'1(t)
-Uz

A
Is(t)

I3(t) CS
I2(t) I 1(
Ut CP
R1
t)
U1 t
CF I1(t) S

B q U 1 .C F
PD Paterns
Voltage Sources

Resonance Test System (AC)

Oscillating Wave Test Very Low Frequency


System (DAC) (VLF)
Generation of damped AC voltage (DAC)

HV Solid - Inductor L
Test Object: power
State Switch Test Object: Power Cable
cable
HV Source

S Cc

For short cable


an additional CC
is required.
HV Divider
Embedded PC HV Divider
PD Coupling Capacitor
Process
200 MHzControl Unit
AD Converter PD Coupling Capacitor
adaptive PD detector
Data Storage PD detector
PD Analysis
Dielectric losses
estimation

OWTS circuit diagram


Oscillating Wave Test System
Monitored DAC Hold Test
Expected Test Results
Issues with Practical Tests

Environment noise

Cross-bonding

Non-terminated end

PD signal attenuation

PD inception time
Issues with Practical Tests

Environment noise

Cross-bonding

Non-terminated end

PD signal attenuation

PD inception time
Issues with Practical Tests

Environment noise

Cross-bonding

Non-terminated end

PD signal attenuation

PD inception time
Issues with Practical Tests

Environment noise

Cross-bonding

Non-terminated end

PD signal attenuation

PD inception time
Issues with Practical Tests

Environment noise

Cross-bonding

Non-terminated end

PD signal attenuation

PD inception time
hank You

asawin.raja@mea.or.th
PD Inception voltage (Ui) , Extinction voltage (Ue) Interpretation
V I II III IV
NO PD Ui>Uo Ui>Uo Ui<Uo
at Uo Ue>Uo Ue<Uo
2*Uo
Peaks higher than 1,4*Uo
1,7*Uo
1,4*Uo
Ui
Uo
Ue

0V
t

50 Hz

PD inception voltage Ui < Operation voltage Uo > Operation voltage Uo


PD extinction voltage Ue < Operation voltage Uo > Operation voltage Uo
PD value (Magnitude) < typical values > Typical values
Location in the cable section Cable insulation Joints or terminals
PD Mappings Local concentration Distibuted along the cable
PD pattern Single pulses (no) repetitive
PD intensity low hogh
Example of Failure

18
Example of Failure

19
Example of Failure

20 22/08/60 20
Example of Failure
MH 76

21 22/08/60 21
Example of Failure
MH 8

22 22/08/60 22
Conductive Type Defect Revealed by DC Test

23 22/08/60 23

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