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US 5,029,039 AGranted
Current adaptive fault indicator
AssigneeSigma Instruments, Inc.
InventorThomas Yeh
Life of this patent
Estimating the term…
Abstract
A fault indicator which senses current in a cable, resets in response to a minimum current and arms a trip arrangement in response to current rising a predetermined amount with respect to time. If the rising current also opens a circuit breaker within a predetermined time and cuts off current to the cable, the indicator trips. If no zero current occurs within the time period, the trip arrangement is disarmed for the next current rise.
Claims12
A fault indicator comprising:
- sensing means for sensing current in a cable;
- reset means responsive to said sensing means for producing a reset indication in response to a minimum current;
- trip means responsive to said sensing means for producing a trip indication in response to both the current rising a predetermined amount with respect to time and a subsequent drop in current to substantially zero.
Dependencies are inferred from the claim text.