LOAD CONTROL DEVICE HAVING A REDUCED LEAKAGE THROUGH GROUND
A load control device for controlling power delivered from an AC power source to an electrical device may be configured to conduct current through earth ground and may disconnect a switching circuit to reduce an amount of current conducted through the earth ground. The load control device may comprise a controllably conductive device configured to control the power delivered from the AC power source to the electrical device so as to generate a switched-hot voltage, a switching circuit electrically coupled with a detect circuit, and a control circuit configured to render the switching circuit conductive and nonconductive. The detect circuit may generate a detect signal indicating a magnitude of the switched-hot voltage. The control circuit may be configured to monitor the detect signal and to render the switching circuit non-conductive after detecting an edge on the detect signal to reduce the total current through the earth ground.
1 . A two-wire electric load control device, comprising:
a controllably conductive device reversibly transitionable between a conductive state and a non-conductive state, the controllably conductive device electrically coupled between a first terminal and a second terminal;
a first detect circuit that includes a first controllable switch reversibly transitionable between a conductive state and a non-conductive state, the first detect circuit electrically coupled between the first terminal of the controllably conductive device and the ground connection;
a second detect circuit that includes a second controllable switch reversibly transitionable between a conductive state and a non-conductive state, the second detect circuit electrically coupled between the second terminal of the controllably conductive device and a ground connection;
control circuitry operatively coupled to the controllably conductive device, the first detect circuit, and the second detect circuit, the control circuitry to:
maintain the controllably conductive device in the non-conductive state;
cause the first controllable switch to transition to the conductive state;
receive, from the first detect circuit an input signal indicative of a presence or an absence of an AC voltage; and
responsive to the receipt, from the first detect circuit, of an input signal indicative of the presence of the AC voltage at the first detect circuit:
cause the first controllable switch to remain in the conductive state; and
receive, from the first detect circuit, an AC source voltage zero crossing input signal.
2 . The two-wire electric load control device of claim 1 , wherein the control circuit to further, responsive to the receipt of an input signal indicative of the absence of the AC voltage at the first detect circuit:
cause the first controllable switch to transition to a non-conductive state; and
cause the second controllable switch to transition to and remain in the conductive state; and
receive, from the second detect circuit, the AC source voltage zero crossing input signal.
3 . The two-wire electric load control device of claim 2 , further comprising:
a user actuatable input device;
wherein the control circuit to further responsive to receipt of an input from the user actuatable input device
determine a controllably conductive device adjustment time period.
4 . The two-wire electric load control device of claim 3 , wherein the control circuit to further:
cause the first controllable switch to transition to the conductive state;
receive, from the first detect circuit, a first AC switched voltage zero crossing input signal;
determine a first wait time period using the determined controllably conductive device adjustment time period;
at conclusion of wait time period cause the controllably conductive device to transition between the conductive state and the non-conductive state;
receive from the first detect circuit, a second AC switched voltage zero crossing input signal;
update adjustment time based on the received second AC switched voltage zero crossing input signal; and
cause the first controllable switch to transition to the non-conductive state.
5 . The two-wire electric load control device of claim 3 , wherein the control circuit to further:
cause the second controllable switch to transition to the conductive state;
receive, from the second detect circuit, a first AC switched voltage zero crossing input signal;
determine a first wait time period using the determined controllably conductive device adjustment time period;
at conclusion of wait time period cause the controllably conductive device to transition between the conductive state and the non-conductive state;
receive from the second detect circuit, a second AC switched voltage zero crossing input signal;
update adjustment time based on the received second AC switched voltage zero crossing input signal; and
cause the second controllable switch to transition to the non-conductive state.
6 . A method to control an electric load device, comprising:
maintaining, by electric load control circuitry, a controllably conductive device in a non-conductive state;
wherein the controllably conductive device reversibly transitions between a conductive state and the non-conductive state, the controllably conductive device electrically coupled between a first terminal and a second terminal causing, by the electric load control circuitry, a first controllable switch included in a first zero-cross detect circuit to transition to a conductive state;
wherein the first controllable switch reversibly transitions between the conductive state and a non-conductive state, the first zero-cross detect circuit electrically coupled between the first terminal of the controllably conductive device and a ground connection;
receiving, by the electric load control circuitry, from the first zero-cross detect circuit an input signal indicative of a presence or an absence of an AC voltage; and
responsive to the receipt, from the first zero-cross detect circuit, of the input signal indicative of the presence of the AC voltage at the first zero-cross detect circuit:
causing, by the electric load control circuitry, the first controllable switch to remain in the conductive state; and
receiving, by the electric load control circuitry, an AC source voltage zero crossing input signal from the first zero-cross detect circuit.
7 . The method of claim 6 , further comprising:
responsive to the receipt, from the first zero-cross detect circuit, of the input signal indicative of the absence of the AC voltage at the first zero-cross detect circuit:
causing, by the electric load control circuitry, the first controllable switch to transition to a non-conductive state; and
causing, by the electric load control circuitry, a second controllable switch included in a second zero-cross detect circuit to transition to and remain in the conductive state;
wherein the second controllable switch reversibly transitions between the conductive state and a non-conductive state, the second zero-cross detect circuit electrically coupled between the second terminal of the controllably conductive device and a ground connection; and
receiving, by the electric load control circuit, the AC source voltage zero crossing input signal from the second zero-cross detect circuit.
8 . The method of claim 7 , further comprising:
receiving, by the electric load control circuit, an input from an operatively coupled user actuatable input device; and
determining, by the electric load control circuit, a controllably conductive device adjustment time period responsive to receipt of the input from the user actuatable input device.
9 . The method of claim 8 , further comprising:
causing, by the electric load control circuit, the first controllable switch to transition to the conductive state;
receiving, by the electric load control circuit, a first AC switched voltage zero crossing input signal from the first detect circuit;
determining, by the electric load control circuit, a first wait time period using the determined controllably conductive device adjustment time period;
causing, by the electric load control circuit, the controllably conductive device to transition between the conductive state and the non-conductive state at the conclusion of wait time period;
receiving, by the electric load control circuit from the first zero-cross detect circuit, a second AC switched voltage zero crossing input signal;
updating, by the electric load control circuit, the adjustment time based on the received second AC switched voltage zero crossing input signal; and
causing, by the electric load control circuit, the first controllable switch to transition to the non-conductive state.
10 . The method of claim 8 , further comprising:
causing, by the electric load control circuit, the second controllable switch to transition to the conductive state;
receiving, by the electric load control circuit from the second zero-cross detect circuit, a first AC switched voltage zero crossing input signal;
determining, by the electric load control circuit, a first wait time period using the determined controllably conductive device adjustment time period;
causing, by the electric load control circuit, the controllably conductive device to transition between the conductive state and the non-conductive state at the conclusion of wait time period;
receiving, by the electric load control circuit from the second zero-cross detect circuit, a second AC switched voltage zero crossing input signal;
updating, by the electric load control circuit, the adjustment time based on the received second AC switched voltage zero crossing input signal; and
causing, by the electric load control circuit, the second controllable switch to transition to the non-conductive state.
11 . A non-transitory, machine readable, storage device that includes instructions that, when executed by electric load control circuitry, causes the electric load control circuitry to:
maintain a controllably conductive device in a non-conductive state;
wherein the controllably conductive device reversibly transitions between a conductive state and the non-conductive state, the controllably conductive device electrically coupled between a first terminal and a second terminal cause a first controllable switch included in a first zero-cross detect circuit to transition to a conductive state;
wherein the first controllable switch reversibly transitions between the conductive state and a non-conductive state, the first zero-cross detect circuit electrically coupled between the first terminal of the controllably conductive device and a ground connection;
receive from the first zero-cross detect circuit an input signal indicative of a presence or an absence of an AC voltage; and
responsive to the receipt, from the first zero-cross detect circuit, of the input signal indicative of the presence of the AC voltage at the first zero-cross detect circuit:
cause the first controllable switch to remain in the conductive state; and
receive an AC source voltage zero crossing input signal from the first zero-cross detect circuit.
12 . The non-transitory, machine readable, storage device of claim 11 wherein the instructions, when executed by the electric load control circuitry, further cause the electric load control circuitry to:
responsive to the receipt, from the first zero-cross detect circuit, of the input signal indicative of the absence of the AC voltage at the first zero-cross detect circuit:
cause the first controllable switch to transition to a non-conductive state; and
cause a second controllable switch included in a second zero-cross detect circuit to transition to and remain in the conductive state;
wherein the second controllable switch reversibly transitions between the conductive state and a non-conductive state, the second zero-cross detect circuit electrically coupled between the second terminal of the controllably conductive device and a ground connection; and
receive the AC source voltage zero crossing input signal from the second zero-cross detect circuit.
13 . The non-transitory, machine readable, storage device of claim 12 wherein the instructions, when executed by the electric load control circuitry, further cause the electric load control circuitry to:
receive an input from an operatively coupled user actuatable input device; and
determine a controllably conductive device adjustment time period responsive to receipt of the input from the user actuatable input device.
14 . The non-transitory, machine readable, storage device of claim 13 wherein the instructions, when executed by the electric load control circuitry, further cause the electric load control circuitry to:
cause the first controllable switch to transition to the conductive state;
receive a first AC switched voltage zero crossing input signal from the first detect circuit;
determine a first wait time period using the determined controllably conductive device adjustment time period;
cause the controllably conductive device to transition between the conductive state and the non-conductive state at the conclusion of wait time period;
receive a second AC switched voltage zero crossing input signal from the first zero-cross detect circuit;
updating, by the electric load control circuit, the adjustment time based on the received second AC switched voltage zero crossing input signal; and
cause the first controllable switch to transition to the non-conductive state.
15 . The non-transitory, machine readable, storage device of claim 13 wherein the instructions, when executed by the electric load control circuitry, further cause the electric load control circuitry to:
cause the second controllable switch to transition to the conductive state;
receive a first AC switched voltage zero crossing input signal from the second zero-cross detect circuit;
determine a first wait time period using the determined controllably conductive device adjustment time period;
cause the controllably conductive device to transition between the conductive state and the non-conductive state at the conclusion of wait time period;
receive a second AC switched voltage zero crossing input signal from the second zero-cross detect circuit;
update the adjustment time based on the received second AC switched voltage zero crossing input signal; and
cause the second controllable switch to transition to the non-conductive state.