Development of a new type of nonlinear resistance valve block for surge arresters. Final report
Present day surge arresters based on silicon carbide material have approached their technological performance limits because of the relatively low degree of nonlinearity in their V-I characteristics. Series gaps were introduced to compensate for this, but the gaps complicate arrester assembly and raise costs, while reducing both protection and reliability. Since 1970, electrical equipment manufacturers have been improving the quality of arresters with material based on zinc oxide. This ceramic material has a very high degree of nonlinearity in its V-I characteristic. The research project conducted here investigated how chemical composition and processing variables affected the electrical and physical characteristics of these metal oxide varistors. Various chemical compositions were studied. Bismuth oxide, antimony oxide, cobalt oxide, manganese oxide, chromium oxide, nickel oxide, and aluminum oxide in a zinc-oxide based varistor were evaluated. The effect of these materials on the varistors' leakage current, discharge voltage, and energy handling capability was evaluated. Mixing procedures and sintering programs were then established for the processing of these varistors. Since the elimination of series gaps would require the metal oxide arrester to be continuously subjected to operating voltage, the work sought to determine the mechanisms and controlling variables affecting a long-term deterioration of these varistors. Based on the electrical modes of conduction, an equivalent circuit model was constructed for the devices. Methods of encapsulating a stack of varistor blocks into an epoxy housing were examined and a potential application for the gapless arrester was demonstrated.
- Research Organization:
- McGraw-Edison Co., Franksville, WI (USA)
- OSTI ID:
- 6712220
- Report Number(s):
- EPRI-EL-1647
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LIGHTNING ARRESTERS
PERFORMANCE TESTING
POWER TRANSMISSION LINES
SURGES
SEMICONDUCTOR RESISTORS
PERFORMANCE
CHEMICAL COMPOSITION
ELECTRICAL FAULTS
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
HVAC SYSTEMS
OXIDES
PHYSICAL PROPERTIES
AC SYSTEMS
CHALCOGENIDES
DATA
ELECTRICAL EQUIPMENT
ENERGY SYSTEMS
EQUIPMENT
INFORMATION
NUMERICAL DATA
OXYGEN COMPOUNDS
POWER SYSTEMS
RESISTORS
SEMICONDUCTOR DEVICES
TESTING
200301* - Power Transmission & Distribution- AC Systems
EHV & UHV- (-1989)