Thyristor tap changer for electrical inductive apparatus

Claim 2

A switching circuit comprising first and second terminals, an electrical inductive winding having a first terminal at one end and a second terminal at the other end and at least one intermediate tap terminal, first, second, third and fourth switching means each having two terminals, said first switching means being connected between said first circuit terminal and said first winding terminal, said second switching means being connected between said first circuit terminal and said second winding terminal, said third switching means being connected between said second circuit terminal and said first winding terminal, and said fourth switching means being connected between said second circuit terminal and said second winding terminal, at least one intermediate switching means connected between said second circuit terminal and said intermediate tap on said winding, control means controlling the conduction of said first, second, third, fourth and intermediate switching means, said control means providing a controlling sequence which always maintains a conduction path between said circuit terminals when the circuit is conducting current, a first conduction path being through said first switching means and said third switching means, a second conduction path being through said first switching means, said winding and said fourth switching means, a third conduction path being through said second switching means and said fourth switching means, a fourth conduction path being through said second switching means, said winding and said third switching means, a fifth conduction path being through said first switching means, part of said winding and said intermediate switching means, and a sixth conduction path being through said second switching means, part of said winding and said intermediate switching means.

Claim 3

A three-phase phase angle regulator comprising a first winding having source, load and center tap terminals, second, third and fourth windings interconnected in three-phase relationship and connected to said center tap terminal, a fifth winding inductively coupled to said first winding and electrically connected to a multiple-winding switching circuit, said multiple-winding switching circuit comprising a plurality of tap windings inductively coupled to said fourth winding with each tap winding having first and second tap winding terminals, each of said tap windings being connected to a switching circuit, said switching circuit comprising first and second circuit terminals, first, second, third and fourth switching means each having two terminals, said first switching means being connected between said first circuit terminal and said first tap winding terminal, said second switching means being connected between said first circuit terminal and said second tap winding terminal, said third switching means being connected between said second circuit terminal and said first tap winding terminal, and said fourth switching means being connected between said second circuit terminal and said second tap winding terminal, control means controlling the conduction of said first, second, third and fourth switching means, said control means providing a controlling sequence which always maintains a conduction path between said circuit terminals when the circuit is conducting current, a first conduction path being through said first switching means and said third switching means, a second conduction path being through said first switching means, said winding and said fourth switching means, a third conduction path being through said second switching means and said fourth switching means, and a fourth conduction path being through said second switching means, said winding and said third switching means, the circuit terminals of the switching circuits of said tap windings being serially interconnected.

Claim 4

A three-phase phase angle regulator comprising a first winding having source, load and center tap terminals, second, third and fourth windings interconnected in three-phase relationship and connected to said center tap terminal, a fifth winding inductively coupled to said first winding and electrically connected to a multiple-winding switching circuit, said multiple-winding switching circuit comprising a plurality of tap windings inductively coupled to said fourth winding with each tap winding having first and second tap winding terminals, each of said tap windings being connected to a switching circuit, said switching circuit comprising first and second circuit terminals, first, second, third and fourth switching means each having two terminals, said first switching means being connected between said first circuit terminal and said first tap winding terminal, said second switching means being connected between said first circuit terminal and said second tap winding terminal, said third switching means being connected between said second circuit terminal and said first tap winding terminal, and said fourth switching means being connected between said second circuit terminal and said second tap winding terminal, control means controlling the conduction of said first, second, third and fourth switching means, said control means providing a controlling sequence which always maintains a conduction path between said circuit terminals when the circuit is conducting current, a first conduction path being through said first switching means and said third switching means, a second conduction path being through said first switching means, said winding and said fourth switching means, a third conduction path being through said second switching means and said fourth switching means, and a fourth conduction path being through said second switching means, said winding and said third switching means, the circuit terminals of the switching circuits of said tap windings being serially interconnected.