Bipolar HVDC transmission system study between +- 600 kV and +- 1200 kV power supply study for insulator pollution tests. Final report
The aim of the project was to determine the required capacity (stiffness) of a dc power supply to be used for flashover tests on contaminated insulators. The present state of the art was based on a survey of the literature which showed that neither the loading effect (maximum leakage current) of the contaminated insulators nor the necessary rectifier parameters have yet been clearly determined. A theoretical investigation revealed the critical factors influencing the flashover voltage. Extensive laboratory studies were performed in IREQ's small fog chamber, where the flashover voltage of heavily contaminated insulators were measured by the clean fog method in which the contaminated and dried insulators were installed in the fog chamber and energized. Then clean fog is applied and the voltage maintained until the flashover occurs or until the leakage current reduces to a few mA. The voltage and the leakage current are recorded by a magnetic-tape recorder. The test is repeated several times to determine the dependence of the 50% flashover voltage on the rectifier parameters. The majority of the contamination tests were performed at the heavy pollution level of about 0.5 mg/cm/sup 2/ of equivalent salt (NaCl) deposit density. The major conclusions of the investigation were: the flashover voltage of contaminated insulators depends on the dynamic voltage drop, smoothing capacitance, and resistance on the ac and dc side of the rectifier; the maximum current before the flashover can be 4 to 4.5 A which is significantly higher than was quoted in the literature; and the dc pollution test requires a rectifier able to provide a current impulse with a peak value of 4 to 4.5 A, a duration of 0.2 to 0.6 s and a charge of 0.2 to 0.5 C, with a dynamic voltage drop of less than 5 to 10% and less than 10% voltage fluctuation.
- Research Organization:
- Hydro-Quebec, Montreal (Canada). Research Inst.
- OSTI ID:
- 7299290
- Report Number(s):
- EPRI-EL-397
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
24 POWER TRANSMISSION AND DISTRIBUTION
AIR POLLUTION
CONTAMINATION
CURRENTS
DC SYSTEMS
DESIGN
ELECTRIC CURRENTS
ELECTRIC DISCHARGES
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLASHOVER
PERFORMANCE TESTING
POLLUTION
POWER SUPPLIES
POWER SYSTEMS
POWER TRANSMISSION LINES
RECTIFIERS
SPECIFICATIONS
SURFACE CONTAMINATION
TEST FACILITIES
TESTING
UHV DC SYSTEMS