| 摘要 |
PURPOSE:To reduce the weight, to save space and to reduce the cost of a phase control type solid state relay by electrically insulating a primary side circuit from a secondary side circuit, and using an optical coupling element for its signal transmission. CONSTITUTION:A phase control type solid state relay has a primary side circuit A and a secondary side circuit B which receives a signal from the circuit A in a state electrically insulated from the circuit A to drive a load L. In the circuit A, a light emitting diode LED1 is connected between input terminals 1a and 1b, and a DC current IF of a level equipment to the conductive angle of phase control is inputted thereto. The circuit B has a snubber circuit 3 connected between output terminals 2a and 2b, a triac TAC1, a full-wave rectifier DB, a trigger circuit 4, a timer 5, and a phototransistor PT1. Thus, time constants are formed by the timer in accordance with current values of the diode LED1 and the phototransistor PT1, thereby controlling a timing for triggering the triac TAC1. |
