Surface hydrophobicity recovery of silicone rubber insulating material post corona ageing is reported in the present work. Recovery rate of hydrophobicity of uncleaned (S1) and cleaned sample (S2) after the corona ageing are compared. Results indicate that surface potential and its decay time constant reduces drastically after the corona ageing, as compared to the virgin specimen. However, the test specimens regain their hydrophobicity, though at a different rate, with time. Trap distribution characteristic shows that the characteristic time and charge trap depth reduces with the corona aged specimens and regain with rest period. A similar trend is observed with contact angle and corona inception voltage (CIV) of the test specimens. Pattern classification of Ultra High Frequency (UHF) discharge signal is done using modified Chaotic Analysis (CA). © 2018 IEEE.

Ramanujam Sarathi

Department of Electrical Engineering

contact angle

Elastomers

hydrophobicity

Information Systems

Information use

Partial discharges

Recovery

RUBBER

Silicone rubber

Silicones

CHAOTIC ANALYSIS

CHARACTERISTIC TIME

CORONA INCEPTION VOLTAGE

decay time constant

HYDROPHOBICITY RECOVERY

SURFACE HYDROPHOBICITY

Trap distributions

Ultra-high frequency

Surface potential

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IIT Madras

Understanding Hydrophobicity Recovery of Silicone Rubber Material Post Corona Ageing

2018 13th International Conference on Industrial and Information Systems, ICIIS 2018 - Proceedings

Corona activity on the surface of silicone rubber has high impact on variation in hydrophobicity of the material, and on corona inception voltage (CIV) of water droplet sitting on the corona degraded surface. The CIV is high under negative DC as compared to positive DC/AC voltages. Increase in conductivity of water droplet reduces CIV. Surface charge accumulation studies indicate that the charge retention capability of the insulating material gets reduced drastically with silicone rubber damaged due to corona causing degradation of surface. Irrespective of the number of cycles of corona discharge activities carried out, the time constant of charge decay, after the removal of charge injection, remains the same. The water droplet initiated discharges under AC and DC voltages radiate UHF signal in the bandwidth 0.3-1.2 GHz. With single droplet sitting on top of the corona damaged silicone rubber, the amount of charge retained by the water droplet is low when the droplet is placed and charged immediately after corona discharge activity to surface of the insulating material. When the water droplet is placed after a certain time period, the charge accumulation characteristics of silicone rubber are regained. Leakage current measured during water droplet discharge studies through recurrent plot (RP) analysis reveals that, under AC voltage, it is possible to classify corona inception, arcing and bridging of water droplet between high voltage and ground electrode. The RP obtained for the current signals generated due to water droplet discharges under positive and negative DC voltages are different. The amount of damage caused to silicone rubber due to water droplet is high under negative DC voltage as compared to positive/AC voltages. While correlating the level of damage to the insulating material due to water droplet and the RQA parameters of RP, it is observed that higher the recurrence rate along with high determinism can cause severe damage to the insulating material. Structural analysis using ATR-FTIR and pyrolysis-GC/MS studies reveal significant functional group variation on surface of silicone rubber, especially when the number of cycles of corona ageing is more. © 2017 IEEE.

IEEE Transactions on Dielectrics and Electrical Insulation

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Journal	Data powered by Typeset2018 13th International Conference on Industrial and Information Systems, ICIIS 2018 - Proceedings
Publisher	Data powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
Open Access	No