| 摘要 |
PURPOSE:To reduce the power consumption of a transistor (TR) of a current supply circuit by providing a protection circuit to a constant current type current supply circuit and suppressing an output current of a ground fault at a normal current or below. CONSTITUTION:When a grounding fault takes place, an excess current flows to a route of TRQ0-resistor R5-power supply E from a terminal A, the voltage at the terminal A rises and exceeds the operating voltage of a nonlinear element D1. When the element D1 is operated, a current flows in the path of element D1-resistor R10-resistor R11-power supply E. Thus, a base current is applied to a TRQ2, which is turned on. Thus, the protection circuit route comprising base of TRQ0-element D2-TRQ2-power supply E is activated, the base current of the TRQ0 is kept constant to apply constant current operation. Thus, the TRQ0 applies a constant current operation with a current being a normal value or below by making the operating voltage of the nonlinear element D2 proper. |
