Undervoltage trip circuit for circuit breaker

Claim 2

A circuit breaker for the protection of an electrical system comprising separable main contacts adapted to be connected in said system, operating means for opening and closing said main contacts, a tripping coil energizable to actuate said operating means to open said main contacts, a primary source of control voltage, first means connected between said source and said tripping coil and actuable to energize said tripping coil from said source, a first voltage divider having the input terminals thereof connected to the output terminals of said source of control voltage, said first divider having a first divider output terminal intermediate said input terminals for providing therefrom relative to one of said input terminals a first divider output voltage which is a fraction of the voltage of said primary source of power, a second voltage divider having the input terminals thereof connected to the output terminals of said primary source of control voltage and including therein a voltage regulating device which provides a generally constant voltage thereacross regardless of the value of the output voltage of said primary source of voltage provided that said last mentioned output voltage is greater in absolute value than a predetermined value, said second divider having a second divider output terminal intermediate said second divider input terminals which is electrically connected to one terminal of said voltage regulating device for providing therefrom relative to one of said second divider input terminals a second divider output voltage which is generally a fraction of said voltage of said primary source and which is generally a constant value provided that said control voltage is generally larger in absolute value than said predetermined value, a multiterminal electrical control device having first and second input terminals connected to said first and second divider output terminals respectively and an output terminal, said multiterminal device producing a pulse of electrical energy at said output terminal when the voltage of said first terminal is significantly different than the voltage of said second terminal, a normally substantially non-conducting gated valve having the gate terminal thereof connected to said output terminal of said multiterminal control device and an output circuit connected between said source and said tripping coil, said output circuit of said valve being actuable by said output pulse to a substantially conducting condition to energize said tripping coil when the voltage of said primary source falls below a predetermined value.

Claim 3

The combination as claimed in claim 1 wherein said voltage regulation device comprised a Zener diode.

Claim 4

The combination as claimed in claim 1 wherein said multiterminal control device comprises a uni-junction transistor, wherein said first terminal comprises the gate terminal of said uni-junction transistor, said second terminal comprised the anode terminal thereof and said output terminal comprises the cathode terminal thereof, said pulse of electrical energy being produced when the voltage at said gate is less by a predetermined value than the voltage at said cathode.

Claim 5

The combination as claimed in claim 3 wherein said voltage regulating device comprises a Zener diode.

Claim 6

The combination as claimed in claim 4 wherein said gated valve comprises a silicon controlled rectifier.

Claim 7

The combination as claimed in claim 1 wherein said gated valve comprises a silicon controlled rectifier.

Claim 8

A circuit breaker for the protection of an electrical system comprising separable main contacts adapted to be connected in said system, operating means for opening and closing said main contacts, a tripping coil energizable to actuate said operating means to open said main contacts, a primary source of control voltage, first means connected between said source and said tripping coil and actuable to energize said tripping coil from said source, a voltage detecting circuit having an input connected to said source and being responsive to the voltage change of said source for producing an output pulse when the magnitude of said voltage decreases below a predetermined value, said voltage detecting circuit having first and second systems for detecting the presence of less than said predetermined minimum value of voltage of said primary source, a normally substantially nonconducting gated valve connected in circuit relationship with said tripping coil, said first system being capable of actuating said gated valve to energize said tripping coil to open said circuit interrupter in the presence of less than said predetermined minimum voltage at the primary source of control voltage when said circuit interrupter is closed, said first system including a first circuit for delaying said actuation of said gated valve for a predetermined time after less than said predetermined minimum voltage at said source of control voltage is first sensed, said first system comprisiNg an electronic signaling device, a plurality of resistive elements, and a voltage reference means connected in circuit relationship with each other, said electronic signaling device having a plurality of input terminals and at least one output terminal, a first of said resistive elements having a movable terminal thereon, said resistive element with said movable terminal being connected in circuit relationship with said source of control voltage, said voltage reference means and a second of said resistive elements being connected in series circuit relationship with each other, the latter series circuit being connected to said primary voltage source in series circuit relationship, said electronic signaling device having a first input terminal connected to said movable terminal of said first resistive element and a second input terminal connected to a junction between the series circuit combination of said second of said resistive elements and said voltage reference means, said junction being maintained at a substantially constant voltage, said output terminal of said electronic signaling device being connected to said gate of said gated electrical valve, said movable terminal of said first resistive element being capable of being adjusted so that when the voltage of said primary source of voltage falls below a predetermined minimum value, the resulting difference in potential between said first and second input terminals of said electronic signaling device will change in such a manner as to produce an output signal at said output terminal of said electronic signaling device capable of actuating said gated electrical valve, said second system being capable of keeping said circuit interrupter open in the presence of less than said predetermined minimum voltage at the source of control voltage, an alternate voltage source comprising a capacitor and a plurality of diodes connected in circuit relationship with said primary voltage source and said gated valve, said capacitor being connected in circuit relationship with said diodes so that said primary voltage source may charge said capacitor, but discharge of said capacitor is substantially through said gated valve when said gated valve has been actuated by said first system to thereby energize said gated valve.

Claim 9

A circuit breaker for the protection of an electrical system comprising separable main contacts adapted to be connected in said system, operating means for opening and closing said main contacts, a tripping coil energizable to actuate said operating means to open said main contacts, a primary source of control voltage, first means connected between said source and said tripping coil and actuable to energize said tripping coil from said source, a voltage detecting circuit having an input connected to said source and being responsive to the voltage change of said source for producing an output pulse when the magnitude of said voltage decreases below a predetermined value, said voltage detecting circuit having first and second systems for detecting the presence of less than said predetermined minimum value of voltage of said primary source, a normally substantially nonconducting gated valve connected in circuit relationship with said tripping coil, said first system being capable of actuating said gated valve to energize said tripping coil to open said circuit interrupter in the presence of less than said predetermined minimum voltage at the primary source of control voltage when said circuit interrupter is closed, said first system including a first circuit for delaying said actuation of said gated valve for a predetermined time after less than said predetermined minimum voltage at said source of control voltage is first sensed, said first system comprisiNg an electronic signaling device, a plurality of resistive elements, and a voltage reference means connected in circuit relationship with each other, said electronic signaling device having a plurality of input terminals and at least one output terminal, a first of said resistive elements having a movable terminal thereon, said resistive element with said movable terminal being connected in circuit relationship with said source of control voltage, said voltage reference means and a second of said resistive elements being connected in series circuit relationship with each other, the latter series circuit being connected to said primary voltage source in series circuit relationship, said electronic signaling device having a first input terminal connected to said movable terminal of said first resistive element and a second input terminal connected to a junction between the series circuit combination of said second of said resistive elements and said voltage reference means, said junction being maintained at a substantially constant voltage, said output terminal of said electronic signaling device being connected to said gate of said gated electrical valve, said movable terminal of said first resistive element being capable of being adjusted so that when the voltage of said primary source of voltage falls below a predetermined minimum value, the resulting difference in potential between said first and second input terminals of said electronic signaling device will change in such a manner as to produce an output signal at said output terminal of said electronic signaling device capable of actuating said gated electrical valve, said second system being capable of keeping said circuit interrupter open in the presence of less than said predetermined minimum voltage at the source of control voltage, an alternate voltage source comprising a capacitor and a plurality of diodes connected in circuit relationship with said primary voltage source and said gated valve, said capacitor being connected in circuit relationship with said diodes so that said primary voltage source may charge said capacitor, but discharge of said capacitor is substantially through said gated valve when said gated valve has been actuated by said first system to thereby energize said gated valve.

Claim 10

An undervoltage detection and triggering means as claimed in claim 7 wherein said first system additionally includes a first pulse shaping capacitance means, a unidirectional current conducting device having a generally fixed voltage drop regardless of the amount of current passed through it connected in series circuit relationship between said first and second input terminals of said electronic signaling device and said first pulse shaping capacitance means, said output terminal of said electronic signaling device being connected to said first pulse shaping capacitance means to form a network to shape said output signal.

Claim 11

An undervoltage detection and triggering means as claimed in claim 8 wherein said gated electrical valve comprises a solid state switch, said electronic signaling device comprises a unijunction transistor having a gate, an anode and a cathode, said diode having an anode and a cathode, said anode of said diode and said gate of said unijunction transistor being connected to said movable terminal of said potentiometer, said cathode of said diode and said anode of said unijunction transistor being connected to said junction of said voltage reference means and said second resistive element, said first circuit comprises a time delay capacitive element and a time delay diode, said time delay capacitive element being connected in parallel circuit relationship with said primary voltage source, said time delay capacitive element receiving charge from said primary voltage source and discharging upon the lowering of the voltage at said primary voltage source, said time delay diode being connected in series circuit relationship between one terminal of said primary voltage source and said first circuit to insure that whEn the primary voltage source decreases, the charge from the said time delay capacitive element is prevented from passing into said primary voltage source.

Claim 12

An undervoltage detection and triggering means as claimed in claim 9 wherein said second system comprises a voltage divider resistance network, said network being connected in series circuit relationship with said primary voltage source, said network including a junction terminal, a second voltage reference means and a remote signaling means being connected in circuit relationship with said junction terminal, said junction terminal being connected to said voltage reference means and said remote signaling means in such a manner that when the voltage of said primary voltage source drops below a predetermined minimum value, said voltage reference means responds to actuate said remote signaling means to prevent the main contacts of said circuit interrupter when open from being closed, said voltage divider resistance network including a fixed resistor connected in series with a variable resistor, said second voltage reference means comprising a Zener diode, said remote signaling means comprising a current actuated switching means connected to prevent energization of said closing coil during at least certain operating conditions, said current actuated switching means comprising a relay having a relay coil and contacts, said relay coil being connected in series circuit relationship with said last-mentioned Zener diode, said relay contacts being normally open, the value of resistance in said voltage divider resistance network being such that when said primary voltage source is above said predetermined minimum value, said Zener diode conducts to thereby energize said relay coil and maintain said contacts in the closed position, thus permitting energization of said closing coil.

Claim 13

An undervoltage detection and triggering means as claimed in claim 10 wherein said solid state switch comprises a silicon controlled rectifier.

Claim 14

An undervoltage detection and triggering means adapted to be connected to a source of voltage comprising a first voltage divider having the input terminals thereof connected to the output terminals of said source of control voltage, said first divider having a first divider output terminal intermediate said input terminals for providing therefrom relative to one of said input terminals a first divider output voltage which is a fraction of the voltage of said primary source of power, a second voltage divider having the input terminals thereof connected to the output terminals of said primary source of control voltage and including therein a voltage regulating device which provides a generally constant voltage thereacross regardless of the value of the output voltage of said primary source of voltage provided that said last mentioned output voltage is greater in absolute value than predetermined value, a second divider output terminal intermediate said second divider input terminals which is electrically connected to one terminal of said voltage regulating device for providing therefrom relative to one of said second divider input terminals a second divider output voltage which is generally a fraction of said voltage of said primary source and which is generally constant provided that said control voltage is generally larger in absolute value than said predetermined value, a multiterminal electrical control device having first and second input terminals connected respectively to said first and second divider output terminals and an output terminal, said multiterminal device producing a pulse of electrical energy at said output terminal when the voltage of said first terminal is significantly different from the voltage of said second terminal, and a normally substantially non-conducting gated valve having the gate terminal thereof connected to said output terminals of said multiterminal control device, said valve being actuable by said output pulse to a substantially conducting condition when said vOltage decreases below said predetermined value to thereby provide an output current from said source.

Claim 15

An undervoltage detection and triggering means adapted to be connected to a source of voltage comprising a first voltage divider having the input terminals thereof connected to the output terminals of said source of control voltage, said first divider having a first divider output terminal intermediate said input terminals for providing therefrom relative to one of said input terminals a first divider output voltage which is a fraction of the voltage of said primary source of power, a second voltage divider having the input terminals thereof connected to the output terminals of said primary source of control voltage and including therein a voltage regulating device which provides a generally constant voltage thereacross regardless of the value of the output voltage of said primary source of voltage provided that said last mentioned output voltage is greater in absolute value than predetermined value, a second divider output terminal intermediate said second divider input terminals which is electrically connected to one terminal of said voltage regulating device for providing therefrom relative to one of said second divider input terminals a second divider output voltage which is generally a fraction of said voltage of said primary source and which is generally constant provided that said control voltage is generally larger in absolute value than said predetermined value, a multiterminal electrical control device having first and second input terminals connected respectively to said first and second divider output terminals and an output terminal, said multiterminal device producing a pulse of electrical energy at said output terminal when the voltage of said first terminal is significantly different from the voltage of said second terminal, and a normally substantially non-conducting gated valve having the gate terminal thereof connected to said output terminals of said multiterminal control device, said valve being actuable by said output pulse to a substantially conducting condition when said vOltage decreases below said predetermined value to thereby provide an output current from said source.

Claim 16

The combination as claimed in claim 12, wherein said voltage regulating device comprised a Zener diode.

Claim 17

The combination as claimed in claim 12 wherein said multiterminal control device comprise a unijunction transistor, wherein said first terminal comprises the gate terminal of said uni-junction transistor, said second terminal comprises the anode terminal thereof and said output terminal comprises the cathode terminal thereof, said pulse of electrical energy being produced when the voltage at said gate is less by a predetermined value than the voltage of said cathode.

Claim 18

The combination as claimed in claim 14 wherein said voltage regulating device comprises a Zener diode.

Claim 19

The combination as claimed in claim 15 wherein said gated valve comprises a silicon controlled rectifier.

Claim 20

The combination as claimed in claim 12 wherein said gated valve comprises a silicon controlled rectifier.

Claim 21

An undervoltage detection and triggering means adapted to be connected to a source of voltage comprising a voltage detecting circuit having an input adapted to be connected to said source and responsive to the voltage of said source for producing an output pulse when said voltage decreases below substantially a predetermined value, a normally substantially nonconducting gated valve connected to said voltage detecting circuit, said valve being actuable by said output pulse to a substantially conducting condition when said voltage decreases below said predetermined value to thereby provide output current from said source, an additional source of voltage connected in circuit relation with said gated valve to assist in providing at least part of said output current when said valve is actuated to said substantially conducting condition, first and second system wherein said first system comprises a first circuit for delaying said actuation of said gated valve for a predetermined time period after the time that less than said predetermined minimum voltage at said primary voltage source is first sensed, said first system comprising an electronic signaling device, a plurality of resistive elements, and a voltage reference means connected in circuit relationship, said electronic signaling device having a plurality of input terminals and at least one output terminal, a first of said resistive elements having a movable terminal, said resistive element with said movable terminal being connected in series circuit relationship with said primary voltage source, said voltage reference means and a second of said resistive elements being connected in series circuit relationship, the latter series circuit being connected to said primary voltage source, said electronic signaling device having a first input terminal connected to said movable terminal of said first resistive element and a second input terminal connected to a junction between the series circuit which includes said second resistive element and said voltage reference means, said junction being maintained at a substantially constant voltage, said output terminal of said electronic signaling device being connected to said gate of said gated electrical valve, said movable terminal of said first resistive element being capable of being adjusted such that when the voltage of said primary voltage source falls below a predetermined minimum value, the resulting difference in potential between said first and second input terminals of said electronic signaling device will change in such a manner as to produce an output signal at said output terminal of said electronic signal device capable of actuating said gated electrical valve, said alternate source of voltage comprising a capacitor and a plurality of diodes connected in circuit relationship with said primary voltage source and said gated valve, said capacitor being connected in circuit relationship with said diodes in such a manner that said primary voltage source may charge sAid capacitor, but discharge of said capacitor is possible only through said gated valve when it is actuated by said first system.

Claim 22

An undervoltage detection and triggering means adapted to be connected to a source of voltage comprising a voltage detecting circuit having an input adapted to be connected to said source and responsive to the voltage of said source for producing an output pulse when said voltage decreases below substantially a predetermined value, a normally substantially nonconducting gated valve connected to said voltage detecting circuit, said valve being actuable by said output pulse to a substantially conducting condition when said voltage decreases below said predetermined value to thereby provide output current from said source, an additional source of voltage connected in circuit relation with said gated valve to assist in providing at least part of said output current when said valve is actuated to said substantially conducting condition, first and second system wherein said first system comprises a first circuit for delaying said actuation of said gated valve for a predetermined time period after the time that less than said predetermined minimum voltage at said primary voltage source is first sensed, said first system comprising an electronic signaling device, a plurality of resistive elements, and a voltage reference means connected in circuit relationship, said electronic signaling device having a plurality of input terminals and at least one output terminal, a first of said resistive elements having a movable terminal, said resistive element with said movable terminal being connected in series circuit relationship with said primary voltage source, said voltage reference means and a second of said resistive elements being connected in series circuit relationship, the latter series circuit being connected to said primary voltage source, said electronic signaling device having a first input terminal connected to said movable terminal of said first resistive element and a second input terminal connected to a junction between the series circuit which includes said second resistive element and said voltage reference means, said junction being maintained at a substantially constant voltage, said output terminal of said electronic signaling device being connected to said gate of said gated electrical valve, said movable terminal of said first resistive element being capable of being adjusted such that when the voltage of said primary voltage source falls below a predetermined minimum value, the resulting difference in potential between said first and second input terminals of said electronic signaling device will change in such a manner as to produce an output signal at said output terminal of said electronic signal device capable of actuating said gated electrical valve, said alternate source of voltage comprising a capacitor and a plurality of diodes connected in circuit relationship with said primary voltage source and said gated valve, said capacitor being connected in circuit relationship with said diodes in such a manner that said primary voltage source may charge sAid capacitor, but discharge of said capacitor is possible only through said gated valve when it is actuated by said first system.

Claim 23

An undervoltage detection and triggering means as claimed in claim 18 wherein said first system includes a unidirectional current carrying device having a generally fixed voltage drop thereacross substantially independent of the amount of current passing therethrough connected in series circuit relationship between said first and second input terminals of said electronic signaling device, a first pulse shaping capacitance means, said output terminal of said electrical signaling device being connected to said first pulse shaping capacitance means to form a network to shape said output signal.

Claim 24

An undervoltage detection and triggering means as claimed in claim 19 wherein said electrical valve comprises a solid state switch, said electronic signaling device comprises a unijunction transistor having a gate, an anode and a cathode, said diode having an anode and a cathode, said anode of said diode and said gate of said unijunction transistor being connected to said movable terminal of said potentiometer, said cathode of said diode and said anode of said unijunction transistor being connected to said junction of said voltage reference means and second resistive element, said first circuit comprises a time delay capacitive element and a time delay diode, said time delay capacitive element being connected in parallel circuit relationship with said primary voltage source, said time delay capacitive element receiving charge from said primary voltage source and discharging upon the lowering of the voltage at said primary voltage source, said time delay diode being connected in series circuit relationship between one terminal of said primary voltage source and said first circuit such that when the primary voltage source decreases, the charge from the said time delay capacitive element is prevented from discharging into said primary voltage source.

Claim 25

An undervoltage detection and triggering means as claimed in claim 20 wherein said second system comprises a voltage divider resistance network, said network being connected in series circuit relationship with said primary voltage source, said network having an interconnected junction terminal, and a second voltage reference means and a remote signaling means are connected in circuit relationship with said junction terminal in such a manner that when the voltage of said primary voltage source drops below a predetermined minimum value, said voltage reference means responds to actuate said remote signaling to prevent an external circuit from being actuated, said voltage divider resistance network comprises a fixed resistor connected in series with a variable resistor, said second voltage reference means comprising a Zener diode, said remote signaling means comprising a current actuated switching means capable of preventing energization of said external circuit, said actuated switching means comprising a relay having a relay coil and contacts, said relay coil being connected in series circuit relationship with said Zener diode, said relay contacts being normally open, the value of resistance in said voltage divider resistance network being such that when said primary voltage source is above said predetermined minimum value, said Zener diode conducts to energize said relay coil to thereby maintain said contacts in the closed position to permit the energization of said closing coil.

Claim 26

An undervoltage detection and triggering means as claimed in claim 21 wherein said solid state switch comprises a silicon controlled rectifier.