Title :
The role of nano-clay in improving circuit-breaker dielectric performance
Author :
Zhang, X. ; Bowler, N. ; Faik, S. ; Siebels, R.L.
Author_Institution :
Dept. of Mater. Sci. & Eng., Iowa State Univ., Ames, IA, USA
Abstract :
The violent event of a short-circuit leads to short-term exposure of circuit breaker components to extremely high current, causing thermal degradation, vaporization and deformation of some components and the deposition of surface contaminants. After short-circuit, the leakage current carried by the breaker, when voltage is applied, increases dramatically but must remain below a certain threshold to meet acceptance criteria. The goal of this study is to identify the primary leakage current pathways through the breaker following short-circuit and to elucidate the role of protective paint, loaded with naturally-occurring clay nanoparticles, on improving the electrical performance of the breaker. A Megger insulation tester was used to test both clean and short-circuited polycarbonate (PC) samples taken from the base of the circuit breaker. Further, direct-current (DC) and alternating-current (AC) conductivity were measured on PC samples by using a Keithley high-resistance meter and broadband dielectric spectroscopy, respectively. These tests established that the leakage current pathway is primarily through the surface contaminants deposited on the PC during the short-circuit event. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to identify the composition of the surface contaminants. These were found to contain significant amounts of metal, accounting for the observed increase in leakage current through the breaker following short-circuit. The protective paint was studied by Fourier transform infrared spectroscopy, SEM and EDS, revealing the critical role played by insulating nanoclay in improving dielectric performance of circuit breaker after short-circuit.
Keywords :
Fourier transform spectra; X-ray chemical analysis; X-ray spectroscopy; circuit breakers; infrared spectra; leakage currents; nanoparticles; scanning electron microscopy; surface contamination; AC conductivity; DC conductivity; EDS; Fourier transform infrared spectroscopy; Keithley high-resistance meter; Megger insulation tester; SEM; alternating-current conductivity; broadband dielectric spectroscopy; circuit breaker components; circuit-breaker dielectric performance; deformation; direct-current conductivity; energy-dispersive X-ray spectroscopy; insulating nanoclay; naturally-occurring clay nanoparticles; primary leakage current pathways; protective paint; protective paint role; scanning electron microscopy; short-circuit event; short-circuit leads; short-circuited polycarbonate; surface contaminant deposition; surface contaminants; thermal degradation; vaporization; Circuit breakers; Coatings; Current measurement; Dielectrics; Leakage current; Pollution measurement; Surface treatment;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena (CEIDP), 2012 Annual Report Conference on
Conference_Location :
Montreal, QC
Print_ISBN :
978-1-4673-1253-0
Electronic_ISBN :
0084-9162
DOI :
10.1109/CEIDP.2012.6378846