Supervision system for monitoring the integrity of a transmission line
First Claim
1. A line supervision system for monitoring the integrity of a pair of transmission line conductors in a detection system of the type having a plurality of individual d-c operated detectors, positioned at various spaced-apart locations in an area to be protected, for detecting the presence of a predetermined undesired condition at each of those locations, each of the detectors being shunt-connected across the conductor pair in order to receive d-c energizing voltage which is applied to the input end of the conductor pair, said line supervision system comprising:
- an end-of-line capacitor connected across the conductor pair beyond the detectors;
means for momentarily interrupting the application of d-c energizing voltage to the conductor pair and at the same time placing a resistive load across the conductor pair'"'"'s input end to provide a discharge path for said capacitor;
integrity testing means, responsive to the voltage developed across said resistive load during the momentary interruption of the d-c energizing voltage, for effectively determining the integrity of the conductor pair;
and indicator means for providing a trouble indication when said integrity testing means senses a trouble condition on the conductor pair and finds that the line integrity is abnormal.
2 Assignments
0 Petitions
Accused Products
Abstract
The integrity of a two-conductor transmission line, over which d-c energizing voltage is supplied to a series of shunt-connected detectors (such as fire and/or smoke detectors) and which line is terminated by an end-of-line capacitor, is monitored and repetitively tested by periodically and momentarily interrupting the application of the d-c energizing voltage to the transmission line or conductor pair, while at the same time connecting a resistive load across the line'"'"'s input end to provide a discharge path for the capacitor. If the integrity is normal, meaning that the line is continuous and not open, and has no excessively high series resistance or excessively low shunt resistance, and also meaning that the capacitor is functioning normally and is not deteriorated, the capacitor will discharge very little during each test and will maintain a relatively high voltage across the resistive load. On the other hand, if there is any trouble on the line giving rise to abnormal integrity, a relatively low voltage will be developed across the resistive load during each test. By sensing the resistive load voltage, the integrity can therefore be determined. When the integrity is found to be abnormal, a trouble indicator provides an appropriate visual and/or audible signal signifying that a trouble condition exists on the conductor pair.
19 Citations
10 Claims
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1. A line supervision system for monitoring the integrity of a pair of transmission line conductors in a detection system of the type having a plurality of individual d-c operated detectors, positioned at various spaced-apart locations in an area to be protected, for detecting the presence of a predetermined undesired condition at each of those locations, each of the detectors being shunt-connected across the conductor pair in order to receive d-c energizing voltage which is applied to the input end of the conductor pair, said line supervision system comprising:
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an end-of-line capacitor connected across the conductor pair beyond the detectors; means for momentarily interrupting the application of d-c energizing voltage to the conductor pair and at the same time placing a resistive load across the conductor pair'"'"'s input end to provide a discharge path for said capacitor; integrity testing means, responsive to the voltage developed across said resistive load during the momentary interruption of the d-c energizing voltage, for effectively determining the integrity of the conductor pair; and indicator means for providing a trouble indication when said integrity testing means senses a trouble condition on the conductor pair and finds that the line integrity is abnormal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A line supervision system for monitoring the integrity of a pair of transmission line conductors in a detection system of the type having a plurality of individual d-c operated detectors, positioned at various spaced-apart locations in an area to be protected, for detecting the presence of a predetermined undesired condition at each of those locations, each of the detectors being shunt-connected across the conductor pair in order to receive d-c energizing voltage which is applied to the input end of the conductor pair, said line supervision system comprising:
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an end-of-line capacitor connected across the conductor pair beyond the detectors; means for momentarily interrupting the application of d-c energizing voltage to the conductor pair; sensing means for effectively sensing the voltage across the input end of the conductor pair, during the momentary interruption of the d-c energizing voltage, to determine the integrity of the conductor pair; and indicator means, controlled by said sensing means, for providing a trouble indication when a trouble condition is detected on the conductor pair.
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10. A line supervision system for monitoring the line integrity of a pair of transmission line conductors in a detection system wherein a plurality of individual d-c operated detectors, disposed along and each shunt-connected across the conductor pair, detect the presence of a predetermined undesired condition at spaced-apart locations in an area to be protected, a D-C power supply being connected to the input end of the conductor pair to apply a d-c energizing voltage of desired magnitude to each of the detectors to effect operation thereof, said line supervision system comprising:
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an end-of-line capacitor, connected across the conductor pair beyond the detectors, normally charged to substantially the magnitude of the d-c energizing voltage; means for momentarily interrupting the application of d-c energizing voltage to the conductor pair and for simultaneously inserting a resistive load across the conductor pair'"'"'s input end, said resistive load constituting a discharge path for said capacitor and producing a voltage signal which reflects the integrity of the conductor pair; means for effectively sensing the signal developed by said resistive load to detect a trouble condition on the conductor pair; and means for providing a trouble indication when a trouble condition is discovered.
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Specification