Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-07-26
1999-03-16
Hofsass, Jeffery A.
Communications: electrical
Condition responsive indicating system
Specific condition
307125, 361 58, 361 59, 361 76, 361 79, 361 85, G08B 2100
Patent
active
058835784
ABSTRACT:
The positive sequence voltage on the power line is measured at a given time, i.e. the present time, and also for one cycle earlier, and the ratio thereof is then compared against a threshold value of 0.9. There are four other supervisory tests which also must be true for a loss of potential condition to be indicated. These include determination of change in positive sequence current and angle and zero sequence current and angle. If the change in those values is smaller than selected thresholds, then a loss of potential condition is indicated.
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Hou Daging
Roberts Jeffrey B.
Hofsass Jeffery A.
Schweitzer Engineering Laboratories Inc.
Tweel , Jr. John
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