| 摘要 |
PURPOSE:To improve noise resistance by supplying electric power to a turning-on circuit, which turns on an auxiliary thyristor, by using the pole voltage of a master thyristor. CONSTITUTION:Electric power for a turning-on circuit 3 is obtained via a diode bridge D1. Therefore, a leakage current IL is never inputted to the gate of a triac 1, so erroneous ignition due to a power noise is eliminated. Even if a noise voltage surpasses the amount of resistance dv/dt, the triac 1 is forced by a resistance R2 and a capacitor C2 to turn on first, thus preventing the destruction of an auxiliary thyristor SCR2. A diode D3 prevents a large negative voltage from being applied to the gate of the SCR2 owing to the leakage current of a diode bridge DO. |
