US 4,338,649 A · System for remotely controlling a load

Abstract

A system adapted to remotely control a transformer relay. The load switch of a transformer relay is controlled by controlling the direction of current flow in the secondary winding. A switch module is coupled with two wires to the secondary winding of the transformer relay providing a unidirectional current flow above a predetermined threshold in the secondary winding in response to a control signal. The unidirectional current flow may be selectively controlled in either direction or may be only purely unidirectional. A control module is then coupled to the switch module momentarily producing the control signal in response to an external stimulus. The switch module, the control module, or both draw a quiescent current from the secondary winding of the transformer relay when the switch module is not activated. The quiescent current is of an amount which is less than the predetermined threshold. In one embodiment the voltage and current at the control device are limited to values less than those available at the secondary winding of the transformer relay.

Claims42

Dependent claims

A system for controlling a transformer relay in response to a stimulus, said transformer relay having a primary winding coupled to an energy source, having a load switch adapted to control the application of said energy source to a load, and having a secondary winding which controls said load switch depending upon the unidirectional flow of current above a predetermined threshold in said secondary winding, comprising:

a switching means coupled to said secondary winding with two wires for allowing, in response to a control signal, a unidirectional current flow in said secondary winding of an amount exceeding said threshold in said secondary winding;
and
a control means operatively coupled to said switching means for momentarily producing said control signal in response to said stimulus;
said switching means and said control means being powered from said secondary winding, drawing a quiescent current of an amount less than said threshold from said secondary winding;
whereby said transformer relay is controlled utilizing only two wires between said secondary winding and said switching means and whereby said control signal may be a signal other than a unidirectional current flow.

2 more elements

A system for controlling a load operating at a first voltage, comprising:

a transformer relay having a primary winding coupled across said first voltage, having a second winding providing a second voltage lower than said first voltage and having a load switch coupled in series with said load, said load switch being latched to an open state when current in said secondary winding momentarily flows in one direction and being latched to a closed state when current in said secondary winding momentarily flows in the opposite direction;
a bidirectional solid state switch having load terminals operatively coupled across said secondary winding and having a gate terminal;
energy limiting means coupled to said bidirectional solid state switch and drawing power from said secondary winding for supplying a power reduced from that power available at said secondary winding;
and
a current control means operatively coupled to said energy limiting means for selectively and momentarily allowing current to flow in one direction only;
whereby said low voltage transformer relay is controlled by utilizing only two wires between said secondary winding and said bidirectional solid state switch and by utilizing only two wires between said bidirectional solid state switch and said current control means;
and
whereby the voltage and current present at said current control means are limited to amounts lower than that required to operate said transformer relay directly.

5 more elements

Dependencies are inferred from the claim text.

System for remotely controlling a load

Life of this patent

System for remotely controlling a load

Life of this patent

Abstract

Claims42