Operation indicator circuit for static overcurrent relays

Claim 2

An operation indicator circuit for static overcurrent relays of the type including a silicon-controlled rectifier serially connected with a contact and associated trip coil of a circuit breaker assembly across a source of unidirectional potential, with the silicon-controlled rectifier being in a nonconductive condition under normal operation of electrical equipment protected by said circuit breaker assembly, and with the siliconcontrolled rectifier being rendered conductive upon a predetermined condition in said equipment to cause a first current flow from said potential source through said controlled rectifier to operate said trip coil to open said circuit breaker assembly, said operation indicator circuit comprising: a capacitor; first indicator means responsive to a second current flow therein for providing an indication of a predetermined condition in said electrical equipment; a charge circuit coupled to said capacitor for enabling said capacitor to charge towards the voltage value of said unidirectional potential source; and means including said silicon-controlled rectifier coupled to said capacitor and to said indicator means for discharging the voltage stored on said capacitor by said charge circuit upon the occurrence of said predetermined condition to provide a closed circuit path including said capacitor, said then conductive controlled rectifier and said first indicator means to produce said second current flow through said indicator means to provide said predetermined condition indication.

Claim 3

An operation indicator circuit as defined in claim 1 wherein said indicator means provides said predetermined condition indication even after said circuit breaker assembly disconnects all power to said electrical equipment in response to current flow through said trip coil.

Claim 4

An operation indicator circuit as defined in claim 1 wherein there is also included second indicator means responsive to current flow therein for providing an indication of a second predetermined condition in said electrical equipment and wherein there is further included means, exclusive of said silicon-controlled rectifier, coupled to said capacitor for discharging the voltage stored on said capacitor after correction of said first predetermined condition in said electrical equipment to permit current flow through said second indicator means to provide said second predetermined condition indication.

Claim 5

An operation indicator circuit as defined in claim 1 wherein there is also included second indicator means responsive to current flow therein for providing an indication of a second predetermined condition in said electrical equipment and wherein there is further included a second capacitor, a charge circuit coupled to said second capacitor for enabling said second capacitor to charge towards the voltage value of said unidirectional potential source and means, exclusive of said silicon-controlled rectifier, coupled to said second capacitor for discharging the voltage stored on said second capacitor after correction of said first predetermined condition in said electrical equipment to permit current flow through said second indicator means to provide said second predetermined condition indication.

Claim 6

An operation indicator circuit as defined in claim 3 wherein there is further included mechanical switch means coupling said capacitor to said silicon-controlled rectifier to enable providing of said first predetermined condition indication and for coupling said capacitor to said last-mentioned means to enable providing of said second predetermined condition indication.

Claim 7

An operation indicator circuit as defined in claim 3 wherein said first predetermined condition is an overcurrent condition in said electrical equipment and wherein said second predetermined condition is a nonovercurrent condition therein.

Claim 8

An operation indicator circuit for static overcurrent relays comprising: first and second terminals; a first series connection between said first and second terminals including a capacitor, a semiconductor diode and a resistor; a second series connection between said first and second terminals including a silicon-controlled rectifier having anode and cathode electrodes, an operating contact of a circuit breaker assembly and a trip coil of said assembly, with the anode electrode of said controlled rectifier coupled to said first terminal; means coupling the end of said resistor remote from said second terminals to the cathode electrode of said silicon-controlled rectifier; indicator means responsive to current flow therethrough for providing an indication of an overcurrent condition in electrical equipment protected by said circuit breaker assembly; said indicator means being connected across said semiconductor diode; a source of unidirectional potential coupled between said first and second terminals; means coupled to control electrode of said silicon-controlled rectifier and responsive to the operating current condition of said electrical equipment for rendering said silicon-controlled rectifier nonconductive under normal operating conditions of said equipment and for rendering said silicon-controlled rectifier conductive upon the occurrence of an overcurrent condition in said equipment; and whereby said capacitor charges to the voltage value of said unidirectional potential source through said semiconductor diode and said resistor under normal operations of said electrical equipment and discharges through said silicon-controlled rectifier and said indicator means upon the occurrence of said overcurrent condition to provide an indication thereof.

Claim 9

An operation indicator circuit for static overcurrent relays comprising: first and second terminals; a first series connection between said first and second terminals including a capacitor, a semiconductor diode and a resistor; a second series connection between said first and second terminals including a silicon-controlled rectifier having anode and cathode electrodes, an operating contact of a circuit breaker assembly and a trip coil of said assembly, with the anode electrode of said controlled rectifier coupled to said first terminal; means coupling the end of said resistor remote from said second terminals to the cathode electrode of said silicon-controlled rectifier; indicator means responsive to current flow therethrough for providing an indication of an overcurrent condition in electrical equipment protected by said circuit breaker assembly; said indicator means being connected across said semiconductor diode; a source of unidirectional potential coupled between said first and second terminals; means coupled to control electrode of said silicon-controlled rectifier and responsive to the operating current condition of said electrical equipment for rendering said silicon-controlled rectifier nonconductive under normal operating conditions of said equipment and for rendering said silicon-controlled rectifier conductive upon the occurrence of an overcurrent condition in said equipment; and whereby said capacitor charges to the voltage value of said unidirectional potential source through said semiconductor diode and said resistor under normal operations of said electrical equipment and discharges through said silicon-controlled rectifier and said indicator means upon the occurrence of said overcurrent condition to provide an indication thereof.

Claim 10

An operation indicator circuit as defined in claim 7 wherein there is further included second indicator means responsive to current flow therethrough for providing an indication of a nonovercurrent condition in said electrical equipment, and means for discharging said capacitor through said second indicator means after correction of said overcurrent condition in said electrical equipment to permit current flow through said second indicator means to provide said nonovercurrent indication condition.

Claim 11

An operation indicator circuit as defined in claim 8 wherein said first indicator means includes a polarity sensitive set coil for providing a visual indication of an overcurrent condition in response to current flow therethrough.

Claim 12

An operation indicator circuit as defined in claim 9 wherein said second indicator means includes a polarity sensitive reset coil responsive to current flow therethrough for providing a visual indication of a nonovercurrent condition being present.