Patent ID: 6104583
Filing Date: 2000-08-15
Classification: H02H

Abstract:
An electrical protection system for connection in series between an electrical power supply and an electrical load to form an operating circuit, and which when so connected protects the circuit from overcurrents, the system having a normal operating condition and a fault condition, and comprising:(1) an integrating current sensing means having(a) a first state when a function of the size of the current passing through the load does not exceed a predetermined value, and(b) a second state when an overcurrent causes said function to exceed said predetermined value;(2) a first circuit switch which(a) has an open state and a closed state, and(b) is coupled to the current sensing means so that, when the first circuit switch is in a closed position and said function increases from below to above said predetermined value, the first circuit switch switches to the open state and remains latched in the open state;(3) a voltage sensing means having(a) a voltage deenergized state when the voltage across the voltage sensing means does not exceed a predetermined voltage amount, and(b) a voltage energized state when the voltage across the voltage sensing means exceeds the predetermined voltage amount;(4) a PTC device; and(5) a second circuit switch which(a) has an open state and a closed state, and(b) is coupled to the voltage sensing means so that, when the second circuit switch is in the closed state, and the voltage sensing means switches from the voltage deenergized state to the voltage energized state, the second circuit switch is converted from the closed state to the open state;the components (1) to (5) being connected so that the first circuit switch, the PTC device and the voltage sensing means are connected in parallel with each other; the second circuit switch, and the parallel combination of the first circuit switch, the PTC device and the voltage sensing means, are connected in series; and, the second circuit switch is a switch which latches in the open state.