Current monitoring system and method

Claim 2

A current monitoring apparatus for detecting the level of current in a given line and for producing an alarm responsive to a predetermined deviation from a current level in said line, said apparatus comprising: means for detecting the level of current flow through said line, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage representative of the measured voltage drop across said impedance in said line, said generating means including an amplifier for amplifying the voltage drop across said impedance so that said output voltage is proportional to the level of current in said line; first reference voltage generating means for generating a first reference voltage representative of a minimum current value in said line; first comparator means coupled to said detecting means and to said first reference voltage generating means for comparing said first reference voltage with said output voltage, said first comparator means generating an alarm signal when said output voltage drops below said first reference voltage; second reference voltage generating means for generating a second reference voltage representative of a maximum current value for said line; said comparator means coupled to said detecting means and to said second reference voltage generating means for comparing said second reference voltage with said output voltage, said second comparator means generating an alarm signal when said output voltage rises above said second reference voltage; and alarm means coupled to said first and second comparator means to produce an alarm when an alarm signal is generated by said first or second comparator means.

Claim 3

A current monitoring apparatus according to claim 1 wherein each of said first and second reference voltage generating means have means for adjusting the reference voltages generated therefrom.

Claim 4

A current monitoring apparatus according to claim 1 and further comprising: a third voltage generating means for generating a voltage representative of a current value in said given line intermediate said minimum current value and a normal current value; third comparator means coupled to said detecting means and to said third reference voltage means for comparing said third reference voltage with said output voltage, said third comparator means generating an alarm signal when said output voltage drops below said third reference voltage; said alarm means coupled to said third comparator means to produce an alarm when said alarm signal is generated by said third comparator means.

Claim 5

A current monitoring apparatus according to claim 3 wherein said alarm comprises a visual alarm and an audible alarm, and there is a separate visual alarm coupled to each of said first, second, and third comparator means.

Claim 6

A current monitoring apparatus according to claim 3 wherein said alarm means comprises a separate alarm coupled to each alarm signal from said first, second, and third comparator means, each of said separate alarms representing a different current condition in said line.

Claim 7

A current monitoring apparatus according to claim 5 and further comprising discriminator means coupled to said first and third comparator means and to said alarm means for blocking said alarm signal to said alarm for said third comparator when said output voltage drops below said first reference voltage, said discriminator means permitting said alarm signaL to pass to said alarm means when said output voltage is at an intermediate value between said first and third reference voltages.

Claim 8

A current monitoring apparatus according to claim 1 and further comprising a third reference voltage generating means for generating a voltage representative of a current value in said line intermediate said maximum current value and a normal current value; third comparator means coupled to said detecting means and to said third reference voltage means for comparing said third reference voltage with said output voltage, said third comparator means generating an alarm signal when said output voltage rises above said third reference voltage; said alarm means coupled to said third comparator means to produce an alarm when said alarm signal is generated by said third comparator means.

Claim 9

A current monitoring apparatus according to claim 1 and further comprising an AC monitoring means including: means for detecting an AC signal in said line; means for sensing the frequency of said AC signal; means coupled to said frequency sensing means for comparing the sensed AC signal frequency with predetermined minimum and maximum AC signal values, and for generating an alarm signal when said sensed AC signal is above or below said predetermined values; and means coupling said alarm means to said alarm signal generating means of said AC frequency comparing means to produce an alarm when said AC signal frequency rises above said maximum signal value or falls below said minimum signal value.

Claim 10

A current monitoring apparatus according to claim 8 and further comprising means for adjusting said minimum and maximum AC signal values.

Claim 11

A current monitoring system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means for generating a current flow through said electrical coupling means; said subscriber station including means to alter the current flow through said electrical coupling means; means at said monitoring station for detecting the level of current flow through said electrical coupling means, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage responsive thereto, said output voltage being proportional to the current level in said electrical coupling means, said generating means including an amplifier for amplifying the voltage drop across said impedance in said electrical coupling means; means coupled to said detecting means for comparing said output voltage with minimum and maximum voltage values representative of predetermined minimum and maximum current values in said electrical coupling means; means for generating an alarm signal when said voltage drops below said minimum value or rises above said maximum voltage value; and alarm means coupled to said alarm signal generating means for producing an alarm responsive to an alarm signal from said alarm signal generating means.

Claim 12

A current monitoring system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means for generating a current flow through said electrical coupling means; said subscriber station including means to alter the current flow through said electrical coupling means; means at said monitoring station for detecting the level of current flow through said electrical coupling means, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage responsive thereto, said output voltage being proportional to the current level in said electrical coupling means, said generating means including an amplifier for amplifying the voltage drop across said impedance in said electrical coupling means; means coupled to said detecting means for comparing said output voltage with minimum and maximum voltage values representative of predetermined minimum and maximum current values in said electrical coupling means; means for generating an alarm signal when said voltage drops below said minimum value or rises above said maximum voltage value; and alarm means coupled to said alarm signal generating means for producing an alarm responsive to an alarm signal from said alarm signal generating means.

Claim 13

A current monitoring system according to claim 10 and further comprising means to adjust said minimum and maximum voltage values.

Claim 14

A current monitoring system according to claim 10 and further comprising means at said subscriber station to impress a given AC frequency signal on said current in said electrical coupling means; means at said monitoring station for detecting said AC frequency and comparing said frequency to minimum and maximum frequency values; means coupled to said comparing means for generating an alarm signal when said frequency drops below said minimum frequency value or rises above said maximum frequency value; and means coupling said alarm signal generating means for said AC signal to said alarm means to produce an alarm when the frequency of said AC signal drops below said minimum value or rises above said maximum value.

Claim 15

A current monitoring system according to claim 12 wherein said comparing means includes means for converting said AC signal to a voltage representative of the frequency of said AC signal; means for generating a reference voltage representative of a minimum frequency level; and means for generating a reference voltage representative of a maximum frequency level.

Claim 16

A current monitoring system according to claim 13 wherein said reference voltage generating means are adjustable to vary said minimum and maximum frequencies for which an alarm is given.

Claim 17

A current monitoring system according to claim 12 wherein at least one of said reference voltage generating means have a plurality of voltage generating means for generating a plurality of different reference voltages; and switch means for singularly coupling each of said voltage generating means to said comparing means whereby different reference voltages can be selectively activated by said switch means.

Claim 18

A current monitoring system according to claim 12 wherein said alarm means includes a first visual alarm to indicate the presence of a frequency below said minimum frequency value, and a second visual alarm to indicate the presence of a frequency above said maximum frequency value.

Claim 21

A method of monitoring current according to claim 17 wherein said generating step includes generating a first alarm signal responsive to said output voltage falling below said minimum current reference voltage, and generating a second alarm signal responsive to said output voltage rising above said maximum current reference voltage; said alarm activating step includes activating a first alarm responsive only to said first alarm signal and activating a second alarm responsive only to said second alarm signal.

Claim 22

A method of monitoring current according to claim 17 and further comprising the step of selectively altering said minimum and maximum reference voltages responsive to a change in the normal level of current in said transmission line.

Claim 23

A method of monitoring current according to claim 17 and further comprising impressing an AC signal in said transmission line; detecting the frequency of said AC signal; comparing said frequency of said AC signal to predetermined maximum or minimum reference frequencies; and generating a second alarm signal when said detected AC signal drops below said predetermined frequency or rises above said predetermined maximum frequency; and activating an alarm responsive to said second alarm signal.

Claim 24

A method of monitoring current according to claim 20 wherein said frequency detecting step includes converting said AC signal to a second output voltage representative of the frequency of said AC signal, and said comparing step comprises comparing said second output voltage with reference voltages representative of minimum and maximum frequencies of said AC signal in said transmission line.

Claim 25

A method of monitoring current according to claim 20 wherein said generating step comprises: generating a first alarm signal responsive to said signal frequency dropping below said predetermined minimum frequency and generating a second alarm signal responsive to said AC signal frequency rising above said predetermined maximum frequency; and said alarm activating step comprises activating a first alarm responsive only to said first alarm signal and activating a second alarm responsive only to said second alarm signal.

Claim 26

An alarm system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means generating a current flow through said electrical coupling means; means at said monitoring station for detecting current flow through said electrical coupling means; means coupled to said detecting means for actuating an alarm at said monitoring station responsive to a drop in said current below a predetermined value or a rise in said current in said electrical coupling means above a predetermined value; means for impressing an AC signal on said electrical coupling means; means at said subscriber station for detecting the frequency of said AC signal; means coupled to said frequency detecting means for comparing said frequency to predetermined minimum and maximum reference frequencies; means coupled to said comparing means for generating an alarm signal when the frequency of said detected AC signal falls below said minimum reference frequency or rises above said reference frequency; and alarm means coupled to said signal generating means for producing an alarm responsive to said alarm signal.

Claim 27

An alarm system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means generating a current flow through said electrical coupling means; means at said monitoring station for detecting current flow through said electrical coupling means; means coupled to said detecting means for actuating an alarm at said monitoring station responsive to a drop in said current below a predetermined value or a rise in said current in said electrical coupling means above a predetermined value; means for impressing an AC signal on said electrical coupling means; means at said subscriber station for detecting the frequency of said AC signal; means coupled to said frequency detecting means for comparing said frequency to predetermined minimum and maximum reference frequencies; means coupled to said comparing means for generating an alarm signal when the frequency of said detected AC signal falls below said minimum reference frequency or rises above said reference frequency; and alarm means coupled to said signal generating means for producing an alarm responsive to said alarm signal.

Claim 28

An alarm system according to claim 23 wherein said comparing means includes means for converting said AC signal to a voltage representative of the frequency of said AC signal; means for generating a reference voltage representative of a minimum frequency level; and means for generating a reference voltage representative of a maximum frequency level.

Claim 29

An alarm system according to claim 24 wherein said reference voltage generating means is adjustable to vary said minimum and maximum frequency values for which an alarm is given.

Claim 30

An alarm system according to claim 25 wherein at least one of said reference voltage generating means has a plurality of voltage generating means for generating a plurality of different reference voltages, and switch means for singularly coupling each of said reference voltage generating means to said comparing means whereby different reference voltages can be selected by activating said switch means.

Claim 31

A current monitoring apparatus for detecting the level of current in a given line and for producing an alarm responsive to a predetermined deviation from a current level in said line, said apparatus comprising: means for detecting the level of current flow through said line, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage representative of the measured voltage drop across said impedance in said line, so that said output voltage is proportional to the level of current in said line; first reference voltage generating means for generating a first reference voltage representative of a minimum current value in said line; first comparator means coupled to said detecting means and to said first reference voltage generating means for comparing said first reference voltage with said output voltage, said first comparator means generating an alarm signal when said output voltage drops below said first reference voltage; second reference voltage generating means for generating a second reference voltage representative of maximum current value for said line; second comparator means coupled to said detecting means and to said second reference voltage generating means for comparing said second reference voltage with said output voltage, said second comparator means generating an alarm signal when said output voltage rises above said second reference voltage; each of said first and second reference voltage generating means having means for generating a plurality of different output voltages, and switch means for singularly coupling each of said output voltage generating means to its respective comparator means; and alarm means coupled to said first and second comparator means to produce an alarm when an alarm signal is generated by said first or second comparator means.

Claim 32

A current monitoring apparatus for detecting the level of current in a given line and for producing an alarm responsive to a predetermined deviation from a current level in said line, said apparatus comprising: means for detecting the level of current flow through said line, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage representative of the measured voltage drop across said impedance in said line, so that said output voltage is proportional to the level of current in said line; first reference voltage generating means for generating a first reference voltage representative of a minimum current value in said line; first comparator means coupled to said detecting means and to said first reference voltage generating means for comparing said first reference voltage with said output voltage, said first comparator means generating an alarm signal when said output voltage drops below said first reference voltage; second reference voltage generating means for generating a second reference voltage representative of maximum current value for said line; second comparator means coupled to said detecting means and to said second reference voltage generating means for comparing said second reference voltage with said output voltage, said second comparator means generating an alarm signal when said output voltage rises above said second reference voltage; each of said first and second reference voltage generating means having means for generating a plurality of different output voltages, and switch means for singularly coupling each of said output voltage generating means to its respective comparator means; and alarm means coupled to said first and second comparator means to produce an alarm when an alarm signal is generated by said first or second comparator means.

Claim 33

A current monitoring apparatus according to claim 27 wherein each of said plurality of voltage generating means is adjustable to vary the output voltage from each of said different voltage generating means.

Claim 34

A current monitoring apparatus for detecting the level of current in a given line and for producing an alarm responsive to a predetermined deviation from a current level in said line, said apparatus comprising: means for detecting the level of current flow through said line, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage representative of the measured voltage drop across said impedance in said line, so that said output voltage is proportional to the level of current in said line; first reference voltage generating means for generating a first reference voltage representative of a minimum current value in said line; first comparator means coupled to said detecting means and to said first reference voltage generating means for comparing said first reference voltage with said output voltage, said first comparator means generating an alarm signal when said output voltage drops below said first reference voltage; second reference voltage generating means for generating a second reference voltage representative of maximum current value for said line; second comparator means coupled to said detecting means and to said second reference voltage generating means for comparing said second reference voltage with said output voltage, said second comparator means generating an alarm signal when said output voltage rises above said second reference voltage; a third voltage generating means for generating a voltage representative of a current value in said given line intermediate said minimum current value and a normal current value; third comparator means coupled to said detecting means and to said third reference voltage means for comparing said third reference voltage with said output voltage, said third comparator means generating an alarm signal when said output voltage drops below said third reference voltage; a fourth reference voltage generating means for generating a voltage representative of a current value in said line intermediate said maximum current value and said normal current value; fourth comparator means coupled to said detecting means and to said fourth reference voltage means for comparing said fourth reference voltage with said output voltage, said fourth comparator means generating an alarm signal when said output voltage rises above said fourth reference voltage; and alarm means coupled to said first, second, third, and fourth comparator means to produce an alarm when an alarm signal is generated by said first, second, third, or fourth comparator means.

Claim 35

A current monitoring apparatus for detecting the level of current in a given line and for producing an alarm responsive to a predetermined deviation from a current level in said line, said apparatus comprising: means for detecting the level of current flow through said line, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage representative of the measured voltage drop across said impedance in said line, so that said output voltage is proportional to the level of current in said line; first reference voltage generating means for generating a first reference voltage representative of a minimum current value in said line; first comparator means coupled to said detecting means and to said first reference voltage generating means for comparing said first reference voltage with said output voltage, said first comparator means generating an alarm signal when said output voltage drops below said first reference voltage; second reference voltage generating means for generating a second reference voltage representative of maximum current value for said line; second comparator means coupled to said detecting means and to said second reference voltage generating means for comparing said second reference voltage with said output voltage, said second comparator means generating an alarm signal when said output voltage rises above said second reference voltage; a third voltage generating means for generating a voltage representative of a current value in said given line intermediate said minimum current value and a normal current value; third comparator means coupled to said detecting means and to said third reference voltage means for comparing said third reference voltage with said output voltage, said third comparator means generating an alarm signal when said output voltage drops below said third reference voltage; a fourth reference voltage generating means for generating a voltage representative of a current value in said line intermediate said maximum current value and said normal current value; fourth comparator means coupled to said detecting means and to said fourth reference voltage means for comparing said fourth reference voltage with said output voltage, said fourth comparator means generating an alarm signal when said output voltage rises above said fourth reference voltage; and alarm means coupled to said first, second, third, and fourth comparator means to produce an alarm when an alarm signal is generated by said first, second, third, or fourth comparator means.

Claim 36

A current monitoring apparatus according to claim 29 wherein said alarm means includes first, second, third, and fourth visual alarms coupled respectively to said first, second, third, and fourth comparator means for giving a visual display of the current level in said line.

Claim 37

A current monitoring apparatus according to claim 30 and further comprising a first discriminator means coupled to said first and third comparator means and to said alarm means for blocking said alarm signal to said alarm means for said third comparator when said output voltage drops below said first reference voltage, said first discriminator means permitting said alarm signal to pass to said aLarm means for said third comparator when said output voltage is at an intermediate value between said first and third reference voltages; a second discriminator means coupled to said second and fourth comparator means and to said alarm means for blocking said alarm signal to said alarm means for said fourth comparator means when said output voltage rises above said second reference voltage, said second discriminator means permitting said alarm signal to pass to said alarm for said fourth comparator when said output voltage is at an intermediate value between said second and fourth reference voltages.

Claim 38

A current monitoring apparatus according to claim 29 wherein each of said first, second, third and fourth voltage generating means have a plurality of voltage generating means for generating a plurality of reference voltages, and switch means for singularly coupling each of said voltage generating means to its respective comparator means.

Claim 39

A current monitoring system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means for generating a current flow through said electrical coupling means; said subscriber station including means for establishing a plurality of different current levels in said electrical coupling means, each current level being representative of a different condition of said subscriber station; means at said monitoring station for detecting the level of current flow through said electrical coupling means, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage responsive thereto, said output voltage being proportional to the current level in said electrical coupling means; means coupled to said detecting means for comparing said output voltage with minimum and maximum voltage values representative of predetermined minimum and maximum current values for each of said current levels in said electrical coupling means; means for generating an alarm signal when said voltage drops below said minimum value or rises above said maximum voltage value for any of said respective current levels; and alarm means coupled to said alarm signal generating means for producing an alarm responsive to an alarm signal from said alarm signal generating means.

Claim 40

A current monitoring system comprising: a subscriber station and a monitoring station; means electrically coupling said subscriber station with said monitoring station; means for generating a current flow through said electrical coupling means; said subscriber station including means for establishing a plurality of different current levels in said electrical coupling means, each current level being representative of a different condition of said subscriber station; means at said monitoring station for detecting the level of current flow through said electrical coupling means, said detecting means including means for measuring the voltage drop across an impedance in said line and for generating an output voltage responsive thereto, said output voltage being proportional to the current level in said electrical coupling means; means coupled to said detecting means for comparing said output voltage with minimum and maximum voltage values representative of predetermined minimum and maximum current values for each of said current levels in said electrical coupling means; means for generating an alarm signal when said voltage drops below said minimum value or rises above said maximum voltage value for any of said respective current levels; and alarm means coupled to said alarm signal generating means for producing an alarm responsive to an alarm signal from said alarm signal generating means.

Claim 41

A current monitoring system according to claim 33 and further comprising a separate alarm for each of said current levels, and means coupling each of said alarms with said comparing means, including means for actuating a single alarm representative of one of said different current levels responsive to an alarm signal from said comparing means such that only one of said alarms will be activated when one of said different current levels is reached in said electrical coupling means.