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Corona Inception Voltage Determination in Electroacoustic Transducer Autotransformers
Rept. for FY1987-FY1988
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
An autotransformer corona inception test circuit has been developed and a prototype has been constructed and demonstrated. Circuit diagrams, component makeup, and component values are presented. Ancillary equipment for the test is identified and recommended, test procedures and precautions are presented, and measured corona inception voltage data and data conclusions, as well as pictorial data are presented for H-core, cup-core, and MPP-core autotransformers. A small but significant percentage of failures in high-power fleet sonar transducers are due to breakdown of electrical insulating or dielectric materials. A physical phenomenon that contributes to these failures is corona a discharge of electricity caused by ionization of the surrounding medium when the voltage gradient exceeds a certain critical value. The frequency of discharge is above 75 kHz. At high operating voltages corona occurs before dielectric breakdown but will, in time, deteriorate insulating materials and cause dielectric failure.
APPROVED FOR PUBLIC RELEASE