Patent attributes
A protective apparatus for protecting electric device connected to an AC circuit from being damaged at a time of misconnection between a live line and a neutral line thereof. The protective apparatus includes a detector, a controller, and an alarm. The detector is connected between the neutral line and the earth line. The controller is connected between the live line and the neutral line and includes a DPDT switch. Two blades of the switch switchably connected to the electric device and the alarm. The detector includes a voltage grading circuit, a rectifier-filter, a detect circuit, and an isolating circuit. Once misconnection between the live line and the neutral line occurs, an abnormal voltage is transformed by the detector to a stable DC power output, which drives the controller to disconnect the device from the live line and the neutral line and activate the alarm.
