| 摘要 |
PURPOSE:To prevent the electric disturbance of the load side circuit from affecting the thyristor circuit as well as to avoid the malfunction of the thyristor by giving the electric insulation or isolation via the photo coupler between the heat-sensitive thyristor circuit and the load side circuit. CONSTITUTION:An optical connection is secured via photo triac 3 and light emitting diode 13 between load circuit 100 in which AC current source 1, load 2 and photo triac 3 are connected in series and heat-sensitive thyristor circuit 200 comprising AC power source 11, rectifying circuit 12, Zener diode 16, diode 13, heat- sensitive thyristor 15 connected to diode 13 and others. In other words, diode 13 emits no light when thyristor 15 is off, and thus triac 3 breaks the power supply to load 2. And diode 13 emits light when the detected temperature increases to turn thyristor 15 on, and thus the power is supplied to load 2. In this case, circuit 200 can be kept at a low potential although circuit 100 features a high potential to ground, thus preventing the electric disturbance effect of circuit 100. Furthermore, the malfunction can be avoided for the thyristor because of a low potential. |
