Selective electronic tripping element
AssigneeSchneider Electric Industries SAS
InventorDominique Boudaud
Life of this patent
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Abstract
The instantaneous tripping threshold of the selective tripping device is a decreasing function of a quantity representative of the time necessary for the current to reach the peak value. The variation curve is disposed between first and second curves, obtained experimentally, representative of envelopes of the peak current values. The first curve is obtained when the circuit breaker associated to the selective tripping device is alone and the second curve when it is connected in series with another circuit breaker connected down-line.
Claims9
A selective electronic tripping device for a circuit breaker, said device comprising:
- current measuring means for measuring current flowing in a circuit breaker;
- processing means connected to the current measuring means and comprising first determining means for determining a first quantity representative of a peak value of such current;
- means for comparing said first quantity with an instantaneous tripping threshold for providing an instantaneous tripping signal when said first quantity exceeds said threshold;
- wherein
- said processing means further comprises second determining means for determining a second quantity representative of an amount of time necessary for such current to reach the peak value, and third determining means for determining the instantaneous tripping threshold according to a decreasing function of the second quantity.
Dependencies are inferred from the claim text.