Arc fault circuit interrupter without dc supply

Abstract From the Canadian patent

Arcing faults are detected by sensing a voltage signal proportional to the rate of change, or di/dt, of the line current when the current steps into an arc fault. A current transformer is used to create the di/dt signal. The transformer has a selected core type number of windings, and size, which saturates at a pre determined level of primary current. The saturation acts to clamp the maximum di/dt voltage signal at the transformer output, and produce a constant output voltage. The constant output voltage eliminates a signal with a high di/dt which may occur, during a lamp burnout from producing a much larger di/dt signal than that caused by an arc fault at a lower level of step current. The …