Cable continuity monitoring system
First Claim
1. A conductor continuity monitoring system for monitoring the continuity of a plurality of cables, each of said cables extending from a common power source to a corresponding one of a plurality of loads to be energized, said monitoring system comprising:
- (a) a plurality of transmitter means, each of said transmitter means transmitting a monitoring signal of predetermined amplitude and frequency to and from a corresponding one of said plurality of loads via a corresponding one of said plurality of cables;
(b) a plurality of receiver means, each of said receiver means receiving monitoring signals returned via a corresponding one of said plurality of cables and via said common power source and determining whether the received monitoring signals are within a predetermined frequency range and above a predetermined amplitude to provide a manifestation indicative thereof, one of said plurality of transmitter means and of receiver means being coupled to one end of said one corresponding cable and said corresponding one load being coupled to the other end of said one corresponding cable; and
(c) a plurality of reference means, each associated with each of said plurality of cables and with a corresponding one of said plurality of transmitter means and responsive to the frequency of the received monitoring signals for generating a reference signal of a frequency substantially equal to the frequency of the received monitoring signals, each of said plurality of transmitter means responsive to said reference signal of said corresponding one of said plurality of reference means for transmitting its monitoring signal at substantially the same frequency as that of the other monitoring signals as transmitted by the other of said plurality of transmitter means, whereby said plurality of monitoring signals as transmitted over said plurality of cables are of substantially the same frequency and as a result no difference signals are produced as would result from frequency shifts being imposed on other ones of said monitoring signals as appear on said plurality of cables and said common power source.
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Accused Products
Abstract
There is disclosed a monitoring system for insuring the continuity and integrity of a power distribution system comprising a plurality of trailing cables, each trailing cable connected at a central station to a common power source and transmitting a power energizing signal to a load disposed at a remote location. In particular, the monitoring system comprises a transmitter and receiver for each trailing cable of the power distribution system whereby a monitoring signal is transmitted from the central station to the remote location and returned to be detected by the receiver. If there is a fault condition within the trailing cable, the receiver provides a signal indicative thereof to be applied to a circuit breaker or coupling switch actuating the coupling switch to its open position thereby disconnecting the power from the trailing cable and its load. When a monitoring signal is successively transmitted and detected, the receiver provides a manifestation indicating the integrity and continuity of its trailing cable and actuates its coupling switch to its closed position, thus applying an energizing signal via its conductor to the load. The transmitter dedicated to each trailing cable includes means responsive to the frequency or frequencies of the previously generated monitoring signals, even from other transmitters, for generating a monitoring signal of substantially the same frequency whereby the monitoring signals as applied via the common AC power bus will be of substantially the same frequency. As a result, the monitoring system of this invention tends to eliminate the production of difference or beat signals and the resultant false indications of a fault condition within one or more of the trailing cables.
73 Citations
13 Claims
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1. A conductor continuity monitoring system for monitoring the continuity of a plurality of cables, each of said cables extending from a common power source to a corresponding one of a plurality of loads to be energized, said monitoring system comprising:
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(a) a plurality of transmitter means, each of said transmitter means transmitting a monitoring signal of predetermined amplitude and frequency to and from a corresponding one of said plurality of loads via a corresponding one of said plurality of cables; (b) a plurality of receiver means, each of said receiver means receiving monitoring signals returned via a corresponding one of said plurality of cables and via said common power source and determining whether the received monitoring signals are within a predetermined frequency range and above a predetermined amplitude to provide a manifestation indicative thereof, one of said plurality of transmitter means and of receiver means being coupled to one end of said one corresponding cable and said corresponding one load being coupled to the other end of said one corresponding cable; and (c) a plurality of reference means, each associated with each of said plurality of cables and with a corresponding one of said plurality of transmitter means and responsive to the frequency of the received monitoring signals for generating a reference signal of a frequency substantially equal to the frequency of the received monitoring signals, each of said plurality of transmitter means responsive to said reference signal of said corresponding one of said plurality of reference means for transmitting its monitoring signal at substantially the same frequency as that of the other monitoring signals as transmitted by the other of said plurality of transmitter means, whereby said plurality of monitoring signals as transmitted over said plurality of cables are of substantially the same frequency and as a result no difference signals are produced as would result from frequency shifts being imposed on other ones of said monitoring signals as appear on said plurality of cables and said common power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification