Multiphase tripping device with short-circuit detection
First Claim
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1. An electronic overcurrent tripping device which senses short circuit current in a multiphase grid with a grid frequency, comprising:
- means for sensing an instantaneous current and an instantaneous voltage in each phase;
means for multiplying each instantaneous current and voltage for obtaining an instantaneous power for each phase;
means for filtering out all dc components of said instantaneous powers, having a passing frequency of twice said grid frequency to generate filtered signals;
a summing circuit, coupled to said means for filtering, which sums the filtered signals to generate a summing output signal;
a comparison circuit, coupled to said summing circuit, which determines when a deviation of said summing output signal exceeds a predetermined threshold level; and
a tripping command transmitter coupled to said comparison circuit and activated by said summing output signal when said summing output signal deviation exceeds said predetermined threshold level.
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Abstract
The invention relates to a device for picking-up voltage and for comparing the instantaneous powers of the individual phases with each other, the output of which is in functional connection with the tripping command transmitter in the event of a predetermined deviation.
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Citations
5 Claims
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1. An electronic overcurrent tripping device which senses short circuit current in a multiphase grid with a grid frequency, comprising:
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means for sensing an instantaneous current and an instantaneous voltage in each phase; means for multiplying each instantaneous current and voltage for obtaining an instantaneous power for each phase; means for filtering out all dc components of said instantaneous powers, having a passing frequency of twice said grid frequency to generate filtered signals; a summing circuit, coupled to said means for filtering, which sums the filtered signals to generate a summing output signal; a comparison circuit, coupled to said summing circuit, which determines when a deviation of said summing output signal exceeds a predetermined threshold level; and a tripping command transmitter coupled to said comparison circuit and activated by said summing output signal when said summing output signal deviation exceeds said predetermined threshold level. - View Dependent Claims (2, 3, 4, 5)
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Specification