| 摘要 |
PURPOSE:To prevent the breakdown of the thyristor by closing the relay at the power break time with the resistor connected in parallel to the inductive load and thus lowering the surge voltage applied across the load. CONSTITUTION:Before opening of contact Aa of the relay which breaks the power supply at the primary side of transformer T, the different relay is actuated to close contact Bb of the relay. Thus resistor R is connected in parallel to inductive load L to reduce the resistance value of resistor R, and as a result the surge voltage occurring across load L can be reduced. Accordingly, the surge voltage applied to the thyristor at the power break time can be lowered without increasing the power loss in the normal state, preventing the breakdown of the thyristor. |
