초록 ▼

An overcurrent protection system containing (1) a current sensing means; (2) a first switch coupled to the current sensing means; (3) a voltage sensing means; (4) a PTC device; and (5) a second switch coupled to the voltage sensing means. In one type of system, the second switch is connected in seri

An overcurrent protection system containing (1) a current sensing means; (2) a first switch coupled to the current sensing means; (3) a voltage sensing means; (4) a PTC device; and (5) a second switch coupled to the voltage sensing means. In one type of system, the second switch is connected in series with a parallel combination of the first switch and the PTC device; and the voltage sensing means is connected in parallel with a series combination of (i) the second switch and (ii) the parallel combination of the first switch and the PTC device. In another type of system, the first switch, the PTC device and the voltage sensing means are connected in parallel with each other; and the second switch (i) is a switch which latches in the open position and (ii) is connected in series with the parallel combination of the first switch, the PTC device and the voltage sensing means.

대표청구항 ▼

[ What is claimed is:] [1.] 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

[ What is claimed is:] [1.] 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; 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.