Assessment diagnostics of the functionality of composite ...
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HC 1 HC 2 HC 3 HC 4 HC 5 HC 6 Assessment diagnostics of the functionality of composite insulators operating in the 150kV power network of Crete N. Mavrikakis 1,* , K. Siderakis 1 , E. Koudoumas 2 and N. Katsarakis 2 1) High Voltage Laboratory, Electrical Engineering Department, Technological Educational Institute of Crete, Greece 2) Center of Materials Technology and Photonics and Electrical Engineering Department, Technological Educational Institute of Crete, Greece * e-mail: [email protected] The performance of high voltage insulators utilized in overhead transmission and distribution lines is a key factor for the reliability of power delivery. At the last 20 years conventional insulators are increasingly replaced by composite insulators with the later providing considerably improved pollution performance. Specifically, in the case of silicone rubber, a more advanced hydrophobicity performance has been developed, capable of recovering the surface behavior even if hydrophilic contaminants are deposited on the material surface. However, surface hydrophobicity, as a material oriented property, is strongly affected by the ageing mechanisms present in service conditions. Actually, the efficiency of the recovery feature, experienced in the case of SIR is related to the housing material condition and the existing stress conditions. In order to reduce the failure probability, combined diagnostic techniques are required for the assessment of the functionality of composite insulators. The results of diagnostic techniques are essential for deciding the maintenance or the replacement of the installed insulators. In this study, an inspection procedure is presented and analyzed, implemented to field aged composite insulators of the 150kV power network of Crete, incorporating electrical, structural and morphological characterization in order to evaluate the condition of field composite insulators. References: [1] STRI Guide 3-2005, “Composite Insulator Status Program: Field inspection of composite line insulators”. [2] Cigre 545, WGB2.21, “Assessment of in-service composite Insulators by using Diagnostic Tools”, August 2013. [3] N. Mavrikakis, K.Siderakis, P.N Mikropoulos, “Laboratory Investigation on Hydrophobicity and Tracking performance of Field Aged Composite Insulators”, UPEC 2014, September 2-5, Romania [4] Technical Specification for Selection and dimensioning of high-voltage insulators intended for use in polluted conditions – Definitions, information and general principles, IEC/TS 60815-1, First Edition, October 2008. [5] International Standard for Electrical insulating materials used under severe ambient conditions – Test methods for evaluating resistance to tracking and erosion, IEC 60587, Third Edition, May 2007 Conclusions: The performance of field aged composite insulators of 150kV network of Crete was successfully evaluated by field and laboratory diagnostic techniques. The field inspection of composite insulators showed: a) increased levels of pollution, b) metal fittings corrosion, c) shed destruction and d) hydrophobicity reduction. The laboratory inspection showed that the degraded, field aged composite insulator is associated with: a) degraded hydrophobic properties, b) low quantity of polymer, c) surface roughness and d) continuous electrical discharge activity. Acknowledgements: Technological Educational Institute of Crete 30 th Panhellenic Conference on Solid-State Physics and Materials Science, Heraklion, Crete, September 21-24, 2014 Abstract 150kV Cretan High Voltage Network Environmental Conditions • High Temperatures • Strong Winds • Marine Pollution Installed Fleet • >50% of insulators are composite, especially Silicone Rubber (SIR) • Up to 20 years old the age of the SIR installed insulators No network faults have been recorded due to pollution. 1. Insulator Sampling I. Visual Observation [1], [2] Pollution Metal Fitting Corrosion Discoloration Destroyed sheds II. Hydrophobicity Classification – Spray Test [1] Hydrophobicity classification according to the shape of the water droplets on the insulator surface after the water mist exposure. HC 6 HC 2 2. Field Inspection 3. Laboratory Inspection [3] A. Physical Analysis I. Contact Angle Measurements II. Pollution Measurements [4] I. FTIR Analysis II. SEM Analysis B. Material Analysis C. Electrical Analysis I. Inclined Plane Test [5] Equivalent Salt Deposit Density (ESDD) & Non Soluble Deposit Density (NSDD) according to IEC 60815 1 2 3 4 5 ESDD NSDD NSDD mg/cm 2 Bond Wavenumber (cm -1 ) Si-O 1100-1000 Si-CH 3 1240-1280 C-H 2960-2962 ATH 3435, (3300-3650) Typical Images Field Inspection showed: Increased levels of pollution Metal fittings corrosion Sheds discoloration Sheds destruction Hydrophobicity reduction SIR ABSORPTION BANDS Experimental conditions: • Five semicircular samples from each insulator were tested • The samples were simultaneously stressed by both: flow of conductive solution and high voltage The high voltage network of Crete can be classified from medium to heavy polluted network. Reduction on the peak values of the FTIR absorbance spectrum for the degraded insulator. The field aged, degraded insulators have rough and cracked surfaces in comparison to the new SIR insulators. Continuous leakage current activity along the surface of the degraded, field aged insulator. The degraded insulator presented the highest average RMS/s value of leakage current. 1. Insulator Sampling from High Voltage Network 2. Field Inspection 3. Laboratory Inspection I. Contact Angle Measurements II. Pollution Measurements I. Fourier Transform Infrared (FTIR) Spectroscopy II. Scanning Electron Microscopy (SEM) I. Visual Observation II. Hydrophobicity Classification A. Physical Analysis B. Material Analysis C. Electrical Analysis I. Inclined Plane Test (IPT) Aims: 1. Performance evaluation of the installed insulators 2. Life estimation of insulators 3. Study of field ageing mechanisms Macroscopic Microscopic Analysis Evaluation Procedure Function • Electrical Insulation • Mechanical Support Composite Insulators Advantages • Hydrophobicity • Low Weight • Low Cost Material • Ceramic • Composite Ceramic Insulators Disadvantages • High maintenance cost • Network Faults in polluted conditions Composite Insulator Anatomy: 1. Metal End Fittings 2. Fiber Glass Core 3. Polymeric Housing Composite Insulators main Disadvantage: Material Degradation due to field ageing mechanisms. • Electrical ageing mechanisms • Mechanical ageing mechanisms • Chemical ageing mechanisms • Pollution • Weather Conditions Degradation of Polymeric Housing caused by: High Voltage Insulators Degraded Insulator: Hydrophilic Non-Degraded Insulator: Hydrophobic Hydrophilic behavior of degraded insulator Hydrophobic behavior of non-degraded insulator Pollution severity classification of field composite insulators Preliminary Measurements Molecular structure of PDMS FTIR absorbance spectra of field aged and new SIR insulators SEM image: New SIR insulator SEM image: Field aged, degraded insulator IPT is implemented according to IEC 60587 in order to evaluate the resistance of SIR insulators against tracking and erosion. IPT arrangement Insulator Leakage Current Average RMS (mA) Leakage Current Max. RMS (mA) Degraded, Field Aged, A 8.2 45.6 Non Degraded, Field Aged, B 4.6 36.5 RMS/s values of leakage currents for a degraded (blue) and a non-degraded (red) field aged insulators during the IPT This work was partly supported by the Polydiagno research project (project code 11SYN-7-1503) which is implemented through the Operational Program “Competitiveness and Enterpreneurship”. Action “Cooperation 2011” and is co-financed by the European Union and Greek national funds (National Strategic Reference Framework 2007-2013). Degraded Insulator Non-Degraded Insulator Contact angle measurements confirm the hydrophobicity reduction of degraded insulators. • The surface leakage current measurements were recorded by an acquisition card with a sampling rate of 2kS/s IPT leakage current measurements
Transcript of Assessment diagnostics of the functionality of composite ...
HC 1 HC 2 HC 3
HC 4 HC 5 HC 6
Assessment diagnostics of the functionality of composite insulators operating in the 150kV power network of Crete
N. Mavrikakis 1,*, K. Siderakis 1, E. Koudoumas 2 and N. Katsarakis 2
1) High Voltage Laboratory, Electrical Engineering Department, Technological Educational Institute of Crete, Greece
2) Center of Materials Technology and Photonics and Electrical Engineering Department, Technological Educational Institute of Crete, Greece *e-mail: [email protected]
The performance of high voltage insulators utilized in overhead transmission and distribution lines is a key factor for the reliability of power delivery. At the last 20 years conventional insulators are increasingly replaced by composite insulators with the later providing considerably improved pollution performance. Specifically, in the case of silicone rubber, a more advanced hydrophobicity performance has been developed, capable of recovering the surface behavior even if hydrophilic contaminants are deposited on the material surface. However, surface hydrophobicity, as a material oriented property, is strongly affected by the ageing mechanisms present in service conditions. Actually, the efficiency of the recovery feature, experienced in the case of SIR is related to the housing material condition and the existing stress conditions. In order to reduce the failure probability, combined diagnostic techniques are required for the assessment of the functionality of composite insulators. The results of diagnostic techniques are essential for deciding the maintenance or the replacement of the installed insulators. In this study, an inspection procedure is presented and analyzed, implemented to field aged composite insulators of the 150kV power network of Crete, incorporating electrical, structural and morphological characterization in order to evaluate the condition of field composite insulators.
References: [1] STRI Guide 3-2005, “Composite Insulator Status Program: Field inspection of composite line insulators”. [2] Cigre 545, WGB2.21, “Assessment of in-service composite Insulators by using Diagnostic Tools”, August 2013. [3] N. Mavrikakis, K.Siderakis, P.N Mikropoulos, “Laboratory Investigation on Hydrophobicity and Tracking performance of Field Aged Composite Insulators”, UPEC 2014, September 2-5, Romania [4] Technical Specification for Selection and dimensioning of high-voltage insulators intended for use in polluted conditions – Definitions, information and general principles, IEC/TS 60815-1, First Edition, October 2008. [5] International Standard for Electrical insulating materials used under severe ambient conditions – Test methods for evaluating resistance to tracking and erosion, IEC 60587, Third Edition, May 2007
Conclusions: The performance of field aged composite insulators of 150kV network of Crete was successfully
evaluated by field and laboratory diagnostic techniques. The field inspection of composite insulators showed: a) increased levels of pollution, b) metal fittings
corrosion, c) shed destruction and d) hydrophobicity reduction.
The laboratory inspection showed that the degraded, field aged composite insulator is associated with:
a) degraded hydrophobic properties, b) low quantity of polymer, c) surface roughness and d) continuous
electrical discharge activity.
Acknowledgements:
Technological
Educational
Institute of Crete
30th Panhellenic Conference on Solid-State Physics and Materials Science, Heraklion, Crete, September 21-24, 2014
Abstract
150kV Cretan High Voltage Network
Environmental Conditions
• High Temperatures
• Strong Winds
• Marine Pollution
Installed Fleet
• >50% of insulators are composite, especially Silicone Rubber (SIR)
• Up to 20 years old the age of the SIR installed insulators
No network faults have been recorded due to pollution.
1. Insulator Sampling
I. Visual Observation [1], [2]
Pollution Metal Fitting Corrosion
Discoloration Destroyed sheds
II. Hydrophobicity Classification – Spray Test [1]
Hydrophobicity classification according to the shape of the water droplets on the insulator surface after the water mist exposure.
HC 6 HC 2
2. Field Inspection
3. Laboratory Inspection [3]
A. Physical Analysis
I. Contact Angle Measurements
II. Pollution Measurements [4]
I. FTIR Analysis
II. SEM Analysis
B. Material Analysis C. Electrical Analysis
I. Inclined Plane Test [5]
Equivalent Salt Deposit Density (ESDD) & Non Soluble Deposit Density (NSDD) according to IEC 60815
1
2
3
4
5
ESDD NSDD
NSD
D m
g/c
m2
Bond Wavenumber (cm-1) Si-O 1100-1000
Si-CH3 1240-1280 C-H 2960-2962 ATH 3435, (3300-3650)
Typic
al Im
ages
Field Inspection showed:
Increased levels of pollution Metal fittings corrosion Sheds discoloration Sheds destruction
Hydrophobicity reduction
SIR ABSORPTION BANDS
Experimental conditions: • Five semicircular samples from each insulator were
tested • The samples were simultaneously stressed by both:
flow of conductive solution and high voltage
The high voltage network of Crete can be classified from medium to heavy polluted network.
Reduction on the peak values of the FTIR absorbance spectrum for the degraded insulator.
The field aged, degraded insulators have rough and cracked surfaces in comparison to the new SIR insulators.
Continuous leakage current activity along the surface of the degraded, field aged insulator.
The degraded insulator presented the highest average RMS/s value of leakage current.
1.
Insulator Sampling
from High Voltage Network
2. Field Inspection
3. Laboratory Inspection
I. Contact Angle Measurements
II. Pollution Measurements
I. Fourier Transform Infrared (FTIR) Spectroscopy
II. Scanning Electron Microscopy (SEM)
I. Visual Observation
II. Hydrophobicity Classification
A. Physical Analysis
B. Material Analysis
C. Electrical Analysis
I. Inclined Plane Test (IPT)
Aims:
1. Performance evaluation of the installed insulators
2. Life estimation of insulators
3. Study of field ageing mechanisms
Macr
osc
opic
M
icro
scopic
Analy
sis
Evaluation Procedure
Function • Electrical Insulation • Mechanical Support
Composite Insulators Advantages • Hydrophobicity • Low Weight • Low Cost
Material • Ceramic • Composite
Ceramic Insulators Disadvantages • High maintenance cost • Network Faults in polluted conditions
Composite Insulator Anatomy: 1. Metal End Fittings 2. Fiber Glass Core 3. Polymeric Housing
Composite Insulators main Disadvantage: Material Degradation due to field ageing mechanisms.
• Electrical ageing mechanisms • Mechanical ageing mechanisms • Chemical ageing mechanisms • Pollution • Weather Conditions
Degradation of Polymeric Housing caused by:
High Voltage Insulators
Degraded Insulator: Hydrophilic
Non-Degraded Insulator: Hydrophobic
Hydrophilic behavior of degraded insulator
Hydrophobic behavior of non-degraded insulator
Pollution severity classification of field composite insulators
Preliminary Pollution Measurements
Molecular structure of PDMS
FTIR absorbance spectra of field aged and new SIR insulators
SEM image: New SIR insulator SEM image: Field aged, degraded insulator
IPT is implemented according to IEC 60587 in order to evaluate the resistance of SIR insulators against tracking and erosion.
IPT arrangement
Insulator Leakage Current Average RMS (mA)
Leakage Current Max. RMS (mA)
Degraded, Field Aged, A 8.2 45.6
Non Degraded, Field Aged, B
4.6 36.5
RMS/s values of leakage currents for a degraded (blue) and a non-degraded (red) field aged insulators during the IPT
This work was partly supported by the Polydiagno research project (project code 11SYN-7-1503) which is implemented through the Operational Program “Competitiveness and Enterpreneurship”. Action “Cooperation 2011” and is co-financed by the European Union and Greek national funds (National Strategic Reference Framework 2007-2013).
Degraded Insulator Non-Degraded Insulator
Contact angle measurements confirm the hydrophobicity reduction of degraded insulators.
• The surface leakage current measurements were recorded by an acquisition card with a sampling rate of 2kS/s
IPT leakage current measurements
