An over-current indica tor

Abstract

The over-current indicator indicates to the user that the current in a circuit is exceeding its rated value as soon as it occurs. The current is sensed by a current transformer (CT) and the rectified and regulated output of the CT is fed to a comparator for detecting over-current. The output of the comparator triggers the indicator circuit that lights up a light emitting diode (LED) when the over-current is detected. The device is designed for operation in 5 A or 10 A rated current circuits, as selected by a toggle switch. The paper describes the device, its principle of operation and the design procedure.