DIFFERENTIAL CURRENT MONITORING METHOD

PURPOSE:To prevent the erroneous operation by exciting rush current by continuing the AND output of a circuit, which detects that the bus voltage is above a specified value, and a circuit, which detects the ON of a breaker, for a certain time. CONSTITUTION:A bus voltage detecting circuit 7 receives...

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Bibliographic Details
Main Author YOKOYAMA TAKAYUKI
Format Patent
LanguageEnglish
Published 09.12.1992
Subjects
CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
ELECTRICITY
EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
GENERATION
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Summary:PURPOSE:To prevent the erroneous operation by exciting rush current by continuing the AND output of a circuit, which detects that the bus voltage is above a specified value, and a circuit, which detects the ON of a breaker, for a certain time. CONSTITUTION:A bus voltage detecting circuit 7 receives the voltage of an A terminal through PT, and outputs a level H when it is above the specified value. When a breaker 'ON' detection circuit 8 detects the 'ON' of the breaker CB-A on the side of A terminal, it outputs a level H. When the AND condition of the output of detection circuits 7 and 8 materializes, an AND circuit 9 outputs a monitor lock signal, which makes a one shot timer 10 continue for a certain time, and by this output, a NOT circuit 11 and an AND circuit 12 lock the output of a differential current monitoring circuit 3. Hereby, even with the device wherein line voltage is not introduced, the erroneous operation by the exciting rush current can be prevented surely in the case that voltage is applied to the transformer of a load terminal.
Bibliography:Application Number: JP19910128099