Prague, 8-11 June 2009 - CIRED · 2018-09-10 · Prague, 8-11 June 2009 1. Introduction 2. Surge Arrester Failures in TNB Distribution 3. Diagnostic Assessment Plan for Surge Arrester

Prague, 8-11 June 2009

Mohd Faris Ariffin – TNB Malaysia Session 1 Paper ID 0674


1. Introduction2. Surge Arrester Failures in TNB Distribution3. Diagnostic Assessment Plan for Surge Arrester4. On-Line Diagnostic Methods for Surge Arrester5. TNB Experience6. Conclusion


Outline of Presentation


Malaysia Isokeraunic Level –200 Thunder Days/Year

Lightning An Issue In Malaysia

Affects Reliability of MV Bare Overhead Line System

Conductor Having Highest Failure Rate

10/94

Lightning in Malaysia




Lightning in Malaysia

10Mean kA (+)

77Max kA(+)

4Min kA (+)

23Mean kA (-)

295Max kA(-)

4Min kA (-)

172.29Expfactor

21Mean kA

295Max kA

4Min kA

8.20524Density

15.9% Positive

1828Count (+)

9681Count (-)

11509Count Ground Stroke Density Statistics for Malaysia in 2007

Dominated by Negative Stroke

Min = 4 kAMax = 295 kAMean = 21kA



Lightning in MalaysiaMV Overhead Lines Failures Cause by Lightning

Typical Major Causes for MVOH System Breakdown in TNB

3%6%

9%

10%

11%

27%

34%

TRANSIENTLIGHTNINGAGEINGTREESANIMALSPOOR CONTACTTHUNDERSTORM



Lightning in MalaysiaTypical 33kV Surge Arrester Used in TNB Distribution

131kV96kV58kVMaximum Residual Voltage @ In09

168kV

24kV

NER/PC

125kV

24kV

22kV

22kV

Class 1

125A @ 2000μsec

100kA

98kV

10kA

9.6kV

NER

21kA

75kV

50Hz

12kV

11kV

11kV

Line Discharge Class13

Long Duration Current Impulse12

High Current Impulse11

221kVHousing Lightning Impulse Withstand10

Nominal Discharge Current (In)08

29kVMax. Cont. Op. Voltage (MCOV)07

NEREarthing System06

Prospective Short-Circuit Current05

170kVLightning Impulse Withstand Level 04

Frequency03

36kVMaximum Voltage02

33kVNominal Voltage01

33kVMandatory SpecificationNo.



S/A Failures in TNB DistributionSurge Arrester Failure Statistics

Typical Root Cause to Surge Arrester Failure in TNB Based on Frequency

6%

6%

6%

19% 63%

LightningAgeingProtection MaloperationAnimalOthers


• Disconnector Expulsed & Dislodged from Damaged S/A Ensuring Disconnection from Healthy System

• Failed Disconnector Tail Causes Transient Tripping as Current Flows Through to Ground

• Detecting Failed S/A Becomes a Challenge

• Undetected Failed S/A a Liability to Asset


S/A Failures in TNB DistributionSurge Arrester Disconnector Tail Failure


• Due to Moisture Ingress ~ Corrosion at Disconnector Tail ⇒ Inability to Dislodge

• Use of PVC Disconnector Tail ~ PVC Hardened ⇒Only Partial Disconnection

Failed Disconnector

Tail


S/A Failures in TNB DistributionSurge Arrester Disconnector Tail Failure


• Exposure to Moisture Leakage through End Fitting

• Usually Related to Wrapped or Slip-in Design – Earlier Technology

• Revision of Technical Specification ~ Use of Polymeric Direct Mould Design to Avoid Voids between Polymeric Housing & Active Parts

• Engineering Practice Update ~ Use of Flexible Copper Braid Instead of PVC Insulated Jumpers


S/A Failures in TNB DistributionMoisture Leakage & Contamination


Silicone Housing

MO Varistor

Fiber Glass WrappingImpregnated with

Epoxy Resin

Wrap Design with Epoxy Resin


S/A Failures in TNB DistributionMoisture Leakage & Contamination

Direct Mould Design

MO Varistors

Direct Moulded SiliconeOn MO Varistor

Fiber Glass Loop


• Higher Requirement for Nominal Discharge Current, Line Discharge Class & BIL for Highly Prone Lightning Areas

• Lightning in Malaysia Mean = 20kA

• Thermal Capabilities to Allow Shorter Cool Down Time to 60 °C


S/A Failures in TNB DistributionExcessive Magnitude & Duration of Lightning Surge


• Considered EOL After 25 to 30 Successful Full Rated Discharge (10 kA) + Numerous Lower Discharge Rating

• Manufacturer’s Recommendation = 15 to 30 Years Depending on Usage

• Which One’s More Accurate?


Surge Arrester Diagnostic PlanSurge Arrester End of Life


Consider the Following Ageing Factors:

• Chronological Age

• Cumulative Service Stress

• Abnormal Event Stress

• Technical Obsolescence


Surge Arrester Diagnostic PlanSurge Arrester End of Life


• Impulse Frequency Flashover Voltage Test• Power Frequency Sparkover Voltage Test• Leakage Current Detection Method• Insulation Resistance Test• Infrared Thermography• Partial Discharge Method (New)


Surge Arrester Diagnostic PlanSuggested Tests & Diagnostic Tools


• Leakage Current Detection• Infrared Thermography• Partial Discharge


Surge Arrester Diagnostic PlanOn-Line Diagnostic Tools - Preferred


• Damaged Surge Arrester Loses Characteristic as Insulator at Power Frequency Voltage

• Presence of Leakage Current > 1 mA for Typical MOV Gapless Surge Arrester

• Develop into Earth Fault

• Causing Transient Tripping

• Measurement of High Leakage Current on Bare S/A Down Lead Raises Safety IssuesMohd Faris Ariffin – TNB Malaysia Session 1 Paper ID 0674

On-Line DiagnosticsLeakage Current Detection Method


• Moisture Ingress Reduces Resistance of S/A• Failed S/A Allows Higher Leakage Current• Heating of S/A• Higher Temperature between 10°C to 20°C Compared

to Healthy S/A


On-Line DiagnosticsInfra Red Thermography


CESI Recommended Thermographic Severity Level

Severity Level

Overheating Range Action Required Time Frame

4 > 35°C Immediate 0

3 10°C - 35°C Short Interval 1 – 2 wks

2 5°C - 9°C Medium Interval 4 – 8 wks

1 2°C - 4°C Notification 24 wks

0 < 1°C No Action 48 wks


On-Line DiagnosticsInfra Red Thermography


• Used for Insulation Integrity

• Determine Health of MOV Blocks

• Utilizes Contact Method Using Ultra Wide Band Radio Frequency to Detect Noise Level Produced by Partial Discharge within MOVMohd Faris Ariffin – TNB Malaysia Session 1 Paper ID 0674

On-Line DiagnosticsPartial Discharge Method


Partial Discharge Method

dB Intensity Correlation to PD Severity LevelSeverity

LevelPD Activity

LevelAction

RequiredTime Frame

(Month) dB Level

1 Nil Nil 12 – 18 < 332 Moderate Retest 12 34 – 403 Medium Repair / Replace 6 41 – 47

4 Medium High Repair / Replace 3 48 – 52

5 High Repair / Replace 1 53 – 59

6 Very High Stop Operation / Replace Immediate > 60


On-Line Diagnostics


Infrared Thermography in TNB Distribution

• Mainly for Transformers & Switchgears• Also for Loose Contact on Overhead Lines• Seldom Used on S/A ~ Passive & Static• CESI Recommends Hot Spot Detection for:

• Conductors• Supports• Bases• Dead End Tension• Suspension Clamps


TNB Distribution Experience


Partial Discharge Field Trial in TNB Distribution

• Field Trial Done in Perak, Selangor, Pahang• Perak Location

• 33kV MFM – Damai Laut Line• 33kV MFM – Pantai Remis Line• 33kV Pantai Remis – Trong Line• 22kV Overhead Lines in Bidor

• High Level of Uncertainty• All Measured S/A Healthy




Partial Discharge Field Trial in TNB Distribution

• Pahang Location• 33kV Tg Batu – Rompin Line• 33kV Rompin – Tg Gemuk Line• 33kV Jengka – Lepar Utara Line• 33kV Muadzam Shah – Selancar Line• 33kV Jerantut – Kuala Tahan Line• 33kV PPU Cini Distribution Substation

• High Level of Uncertainty• Mostly Measured S/A Healthy




Location Position R Y BJRNT-HTLG 001 Incoming 25.6 dB 22.3 dB 17.1 dB

JRNT-HTLG 001 Outgoing 22.0 dB 16.0 dB 23.0 dB

JRNT-HTLG 217 Incoming 17.0 dB 25.7 dB 18.5 dB






BMS-SEL 001* Outgoing 26.3 dB 27.3 dB 26.7 dB

BMS-SEL 128 Incoming 08.0 dB 12.0 dB 16.7 dB

BMS-SEL 133 Incoming 10.4 dB 13.3 dB 10.2 dB

BMS-SEL 133 AR Incoming 15.5 dB 12.6 dB 11.6 dB

BMS-SEL 133 AR Outgoing 07.5 dB 08.2 dB 10.4 dB

BMS-SEL 196* Incoming 23.0 dB 34.4 dB 14.6 dB

BMS-SEL 199 AR Incoming 12.3 dB 12.6 dB 12.0 dB

BMS-SEL 199 AR Outgoing 22.0 dB 16.3 dB 20.0 dB

JENG-FLU 001 Incoming 09.2 dB 08.7 dB 10.0 dB

JENG-FLU 001 Outgoing 10.2 dB 14.1 dB 14.1 dB

JENG-FLU 002* Incoming 11.0 dB 04.7 dB 10.8 dB

JENG-FLU 004* Incoming 14.0 dB 11.8 dB 16.7 dB




JENG-FLU PPU Incoming 26.7 dB 10.6 dB 11.6 dB

Location Position R Y BC-CT 001 PPU C Incoming 13.5 dB 17.7 dB 12.7 dB

C-CT 002 Incoming 19.8 dB 56.3 dB 57.9 dB

C-CT 002 Outgoing 24.0 dB 21.3 dB 17.3 dB

C-CT 059 Incoming 19.2 dB 23.4 dB 12.2 dB

PPU CT AR Incoming 16.1 dB 21.0 dB 20.4 dB


TNB Distribution ExperiencePartial Discharge Field Trial in TNB Distribution


Partial Discharge Field Trial in TNB DistributionTB-KR 001 Incoming 02.5 dB 02.5 dB 01.0 dB

TB-KR 028 Incoming 03.1 dB 34.0 dB 06.9 dB



TB-KR 131-01 Incoming 05.1 dB 00.2 dB 26.7 dB

TB-KR 131-10* Incoming 03.1 dB 10.4 dB 05.1 dB










TJBU-SGCG 01 Incoming 06.3 dB 02.9 dB 02.5 dB

TJBU-SGCG 22/1 Incoming 02.9 dB 01.0 dB 02.9 dB




RMPN-TGCK 013 Incoming 23.6 dB 24.9 dB 20.8 dB


RMPN-TGCK 081 Outgoing 0.98 dB 07.2 dB 21.6 dB




RMPN-TGCK 181 Outgoing 24.2 dB 25.3 dB 22.6 dB




• Interpretation of Results from TNB Pahang• 159/168 Measured as Healthy S/A• 6/168 having Moderate PD – 12 months• 3/68 having Medium High PD – 3 months

•PD Testing on S/A New ~ Hi-Uncertainty Level• But ~ Better Control for Replacement Strategy• Provide Tangible Reliability Status of OHL• Allow Better Budget Prioritization


TNB Distribution ExperiencePartial Discharge Field Trial in TNB Distribution



TNB Distribution ExperienceInsulation Resistance Test on Faulty Surge Arrester

SA 04

SA 03

SA 02

SA 01

Arrester Specimen

1704

1873

3482

1851

Impedance (GΩ)No.

Source: TNB Research


1. Low Confidence Level as PD Measurement for Surge Arrester is New

2. Question in Accuracy of PD Measurement ~ Comparative Study with IR Thermography & Leakage Current Necessary

3. Off-Line & Lab Testing Unable to Confirm Surge Arrester Failure

4. Diagnostic Tools Giving Tangible Measurement Gives Educated Guess on Surge Arrester Health


Conclusion


5. Allows Techno-Economic Planning i.e. Replacement & Retirement Strategy & Budgeting Priority

6. Gives Opportunity for Structured Condition Monitoring Basis and End-of-Life Evaluation for Surge Arrester


Conclusion


Contacts:[email protected]

Ir. Mohd Faris AriffinEngineering Dept., Distribution Division,TNB

Level 11, Wisma TNBNo. 19, Jln Timur

46200 Petaling Jaya, Selangor, MALAYSIA

Tel: +603-79679183 Fax: +603-79572895

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Prague, 8-11 June 2009 - CIRED · 2018-09-10 · Prague, 8-11 June 2009 1. Introduction 2. Surge Arrester Failures in TNB Distribution 3. Diagnostic Assessment Plan for Surge Arrester

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