Patent ID: 6969927
Filing Date: 2005-11-29
Classification: H02J,Y02B,Y02E,Y04S

Abstract:
1. A power switching apparatus adapted for connection between an alternate current power source and a load, said power switching apparatus comprising power switching means for making and breaking electrical connection between said alternate current power source and said load, electronic control circuitry for controlling and operating said power switching means, power coupling means for coupling operating power from said alternate current power source for operation of said electronic control circuitry, said power coupling means including an “ON” state power supply circuit comprising a current transformer with coupled primary and secondary windings, said primary windings being adapted for series connection between said alternate current power source and said load, said secondary windings being connected for coupling power from said primary windings to said electronic control circuitry, said primary windings comprising first and second sub-primary windings of different number of turns of windings of different core diameter, said first sub-primary windings being of a significantly larger current rating than said second sub-primary windings, a current conduction path being provided from intermediate said first and said second sub-primary windings to said power switching means so that a upon detection of a current exceeding the current rating of said second sub-primary windings, current will be caused to flow from said alternate current power source to said load via a current loop comprising said power switching means and said first sub-primary windings, the number of windings of said second sub-primary windings being more than that of said first sub-primary windings and is adapted for providing the operating power of said electronic control circuitry when the current flowing through said primary windings is below a pre-determined threshold level.