Abstract: A lightning current responsive alarm device in which an earthed discharge current circuit consisting of a parallel combination of a non-linear resistor and an inductive impedance element is connected between a protective coordination gap in a power transmission system and earth. In the device, a capacitor is charged up with the drop voltage appearing across the nonlinear resistor, and a sensor or counter is actuated by the discharge current of the capacitor, so that the device can operate with a greatly widened operating range which covers a large current region of lightning current.

Abstract: In a puffer type gas circuit breaker comprising at least a pair of main movable and fixed contacts, a puffer device and a pair of preinsertion resistor contacts inserted electrically in parallel with the main movable and fixed contacts, the preinsertion resistor contacts are closed prior to the closing of the main movable and fixed contacts, and are separated a short time after the main movable and fixed contacts have been closed.