| 摘要 |
PURPOSE:To reduce the capacity of a thyristor and to reduce the quantity of heat generated from the thyristor by providing structure for supplying power source power through the thyristor to a load or directly supplying it to the load without interposing the thyristor. CONSTITUTION:A circuit for bypassing the high-order side and low-order side of a thyristor 3 is provided, and a C contact (changeover switch) 7 to be operated by a microcomputer 5 is provided at a branching point on the high-order side of the thyristor 3. When power to be applied to a load 2 is lower than the power supplied to a power source 1, the changeover switch 7 is switched to the side of the thyristor 3, the thyristor 3 is controlled by the microcomputer 5, an AC voltage to be applied to the load 2 is controlled, and the power supplied to the power source 1 is reduced to required power and applied to the load 2. When the power to be applied to the load 2 exceeds the range requiring the control due to the thyristor 3, the changeover switch 7 is switched to the bypass circuit side, and the power supplied to the power source 1 is directly applied to the load 2 without interposing the thyristor 3. |
