| 摘要 |
PURPOSE:To obtain a protecting circuit of an SCR with an easy constitution by using, for example, an electric lamp whose resistance value is increased according as a current is increased. CONSTITUTION:Though the voltage between both ends of an electric lamp VR is an interrupted waveform P when the SCR is in the normal state, this voltage becomes continuous as shown by a waveform Q in Fig. if a short-circuit trouble occurs in the SCR. When this trouble occurs, the resistance value of the electric lamp is increased to fulfill the protecting function, and simultaneously, the voltage of a capacitor C1 rises quickly. An exciting current is flowed to a relay R2 by this voltage, and a contact S is opened to cut off the supply of AC power. |
