Abstract: A solid state circuit protector is comprised of a coil winding, a latching type Hall effect device, and a solid state switching network including an NPN bipolar junction transistor with a current limiting resistor. Other types of solid state switches can be employed instead of or in addition to the bipolar junction transistor.

Abstract: Circuit protectors employing a reed switch or electromechanical switching device, has a primary coil connected in series with it. Two resistors are connected across the switch/device and series connected primary coil. A secondary coil is connected across the load to the juncture of the two resistors. The primary and secondary coils are concentric windings. The switch/device is open when there is no power supplied. Thus, the two resistors and the secondary coil are connected to the load. The values of the two resistors and the secondary coil are chosen so that the coil current increases when the power supply is turned ON. When the load reaches approximately 80% of its full level, the magnetic flux generated by a secondary coil winding is sufficient to cause the switch or device contacts to close. As the load reaches its normal state, the secondary coil continues to hold the contacts closed.