Abstract: A current detecting device includes an exciting coil (3) wound around a magnetic core (2) enclosing a conductor through which flows a measurement current, and an oscillator circuit (4) that generates a square wave voltage which is supplied to the exciting coil (3). Furthermore, the current detecting device includes a duty detector circuit (5) that detects the measurement current based on variation in the duty ratio of the square wave voltage output from the oscillator circuit (4), a frequency detector circuit (7) that detects an overcurrent of the measurement current based on the frequency of the square wave voltage output from the oscillator circuit (4), and an oscillation amplitude detector circuit (6) that detects an overcurrent of the measurement current based on the magnitude of the square wave voltage output from the oscillator circuit (4).

Abstract: A current detecting device includes an exciting coil (3) wound around a magnetic core (2) enclosing a conductor through which flows a measurement current, and an oscillator circuit (4) that generates a square wave voltage which is supplied to the exciting coil (3). Furthermore, the current detecting device includes a duty detector circuit (5) that detects the measurement current based on variation in the duty ratio of the square wave voltage output from the oscillator circuit (4), a frequency detector circuit (7) that detects an overcurrent of the measurement current based on the frequency of the square wave voltage output from the oscillator circuit (4), and an oscillation amplitude detector circuit (6) that detects an overcurrent of the measurement current based on the magnitude of the square wave voltage output from the oscillator circuit (4).