Load current monitoring device for detecting predetermined degree of change in load impedance
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United States of America Patent
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-
Sep 3, 1985
Grant Date -
N/A
app pub date -
Dec 30, 1982
filing date -
Dec 30, 1982
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Current provided to a generally constant impedance load is monitored to detect a predetermined load current decrease not resulting from normal load voltage fluctuations, such decrease indicating an abnormal increase in load impedance. A latching alarm is actuated when the predetermined load current decrease is detected. The degree of load current decrease tolerable without activating the alarm is determined by a user-adjustable percentage-of-change sensitivity control. A logic gate blocks alarm functions when the load current decreases to an abnormally low level. The disclosed device can be used to monitor the status of a line voltage energized heat trace cable constituted by a plurality of parallel-connected resistance wire heating elements. Multiple monitoring devices can be used in conjunction with a master alarm which can be reset without resetting the particular monitoring device alarm that triggered the master alarm.
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