Thermally sensitive switch device

A thermally sensitive switch device comprising a main thyristor including a cathode electrode, and an anode electrode and a gate electrode, a source of alternating current and a load connected in series, said cathode electrode and said anode electrode being connected across said source of alternating current and said load, a thermally sensitive thyristor including an anode electrode, a cathode electrode, and a gate electrode, said cathode electrode of said thermally sensitive thyristor being connected to said gate electrode of said main thyristor, a resistor, said anode electrode of said thermally sensitive thyristor being connected to said anode electrode of said main thyristor through said resistor, said thermally sensitive thyristor being brought into its conducting state at a junction temperature thereof in excess of a predetermined magnitude, and a variable resistor connected across said gate and said cathode electrodes of said thermally sensitive thyristor to control said predetermined junction temperature, whereby a gate triggering current is supplied to said main thyristor through said thermally sensitive thyristor in its conducting state.

A thermally sensitive switch device comprising a main thyristor including a cathode electrode, an anode electrode and a gate electrode, a source of alternating current and a load connected in series, said cathode electrode and said anode electrode being connected across said source of alternating current and said load, a first resistor, a triggering capacitor connected across said anode and said gate electrodes of said main thyristor through said first resistor, a second resistor connected across said gate and said cathode electrodes of said main thyristor to form a circuit for charging the triggering capacitor with said first resistor and said triggering capacitor, a thermally sensitive thyristor including a cathode electrode connected to said cathode electrode of said main thyristor, an anode electrode connected to said gate electrode of said main thyristor and a gate electrode, said thermally sensitive thyristor being brought into its conducting state at a junction temperature thereof in excess of a predetermined magnitude, and a variable resistor connected across said gate and said cathode electrodes of said thermally sensitive thyristor to control said predetermined junction temperature, whereby a gate triggering current supplied to said main thyristor is bypassed through said thermally sensitive thyristor in its conducting state.

A thermally sensitive switch device comprising a main thyristor including a cathode electrode, an anode electrode and a gate electrode, a rectifier means, said cathode and said anode electrodes being connected across said rectifier means, a thermally sensitive thyristor including an anode electrode, a cathode electrode and a gate electrode, said cathode electrode of said thermally sensitive thyristor being connected to said gate electrode of said main thyristor, said anode electrode of said thermally sensitive thyristor being a voltage dividing resistor connected across said cathode and said anode electrodes of said main thyristor, connected to an intermediate point on said voltage dividing resistor, said thermally sensitive thyristor being brought into its conducting state at a junction temperature thereof in excess of a predetermined magnitude, and a variable resistor connected across said gate and said cathode electrodes of said thermally sensitive thyristor to control said predetermined junction temperature, whereby a gate triggering current is supplied to the main thyristor through said thermally sensitive thyristor in its conducting state.

A thermally sensitive switch device comprising a main thyristor including a cathode electrode, an anode electrode and a gate electrode, a rectifier means, said cathode and said anode electrodes being connected across said rectifier means, a thermally sensitive thyristor including an anode electrode, a cathode electrode and a gate electrode, said cathode electrode of said thermally sensitive thyristor being connected to said cathode electrode of said main thyristor, a resistor, said anode electrode of said thermally sensitive thyristor being connected to said anode electrode of said main thyristor through said resistor, said thermally sensitive thyrsitor being brought into its conducting state at a junction temperature thereof in excess of a predetermined magnitude, and a variable resistor connected across said gate and said cathode electrodes of said thermally sensitive thyristor, and a unidirectional diode connected across the anode electrode of said thermally sensitive thyristor and the gate electrode of said main thyristor for supplying a gate triggering current to said main thyristor, whereby the gate triggering current is bypassed through said thermally sensitive thyristor in its conducting state.