Load control device for high-efficiency loads

A method of controlling power delivered from an AC power source to a lighting load to control an intensity of the lighting load, the method comprising:

• controlling a gate current path to conduct a pulse of current through a gate terminal of a thyristor at a firing time during a half-cycle of the AC power source to cause the thyristor to conduct current through first and second main terminals of the thyristor to energize the lighting load, wherein the first and second main terminals of the thyristor are electrically coupled between the AC power source and the lighting load;
• when using a first start-up routine to turn on the electrical load, controlling the gate current path, during the half-cycle of the AC power source, to conduct a single pulse of current through the gate terminal of the thyristor at the firing time to attempt to render the thyristor conductive;
• when using a second start-up routine to turn on the electrical load, controlling the gate current path during the half-cycle of the AC power source to conduct a first pulse of current through the gate terminal of the thyristor to attempt to render the thyristor conductive at the firing time and conduct a second pulse of current through the gate terminal of the thyristor after the firing time;
• performing the second start-up routine to turn on the electrical load;
• detecting a fault condition while turning on the electrical load using the second start-up routine, and
• switching to the first start-up routine to turn on the electrical load.

A method of controlling power delivered from an AC power source to a lighting load to control an intensity of the lighting load, the method comprising:

• controlling a gate current path to conduct a pulse of current through a gate terminal of a thyristor at a firing time during a half-cycle of the AC power source to cause the thyristor to conduct current through first and second main terminals of the thyristor to energize the lighting load, wherein the first and second main terminals of the thyristor are electrically coupled between the AC power source and the lighting load;
• when using a first start-up routine to turn on the electrical load, controlling the gate current path, during the half-cycle of the AC power source, to conduct a single pulse of current through the gate terminal of the thyristor at the firing time to attempt to render the thyristor conductive;
• when using a second start-up routine to turn on the electrical load, controlling the gate current path during the half-cycle of the AC power source to conduct a first pulse of current through the gate terminal of the thyristor to attempt to render the thyristor conductive at the firing time and conduct a second pulse of current through the gate terminal of the thyristor after the firing time;
• performing the first start-up routine to turn on the electrical load;
• detecting a fault condition while turning on the electrical load using the first start-up routine;
• and
• switching to the second start-up routine to turn on the electrical load.