초록 ▼

An overcurrent protection system which will give a rapid response to relatively small overcurrents. The system, which can be connected between an electrical power supply and an electrical load to form an operating circuit, and which when so connected protects the circuit from overcurrents, has a nor

An overcurrent protection system which will give a rapid response to relatively small overcurrents. The system, which can be connected between an electrical power supply and an electrical load to form an operating circuit, and which when so connected protects the circuit from overcurrents, has a normal operating condition and a fault condition, and comprises: a circuit interruption element having, (1) a normal state which permits the flow of a normal current, INORMAL, when the system is in the normal operating condition, and (2) a fault state which permits the flow of at most a reduced current, substantially less than INORMAL, when the system is in the fault condition; and a control element, connected in series with the circuit interruption element, the control element having a variable resistance which (1) is low when the current in the system does not exceed the normal current, INORMAL, by a predetermined current amount, and (2) increases by at least a predetermined resistance amount when the current in the system exceeds the normal current, INORMAL, by the predetermined current amount; the circuit interruption element changing from its normal state to its fault state, thereby causing the system to change from its normal operating condition to its fault condition, when the resistance of the control element has increased by the predetermined resistance amount.

대표청구항 ▼

An electrical system which can be connected 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: a. a circuit in

An electrical system which can be connected 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: a. a circuit interruption element having, (1) a normal state which permits the flow of a normal current, INORMAL, when the system is in the normal operating condition, and (2) a fault state which permits the flow of at most a reduced current, substantially less than INORMAL, when the system is in the fault condition; and b. a control element, which is connected in series with the circuit interruption element, the control element having a variable resistance which (1) is low when the current in the system does not exceed the normal current, INORMAL, by a predetermined current amount, and (2) increases by at least a predetermined resistance amount when the current in the system exceeds the normal current INORMAL, by the predetermined current amount; and comprising a series combination of: (a) a current sensing means having (i) a current deenergized state, when the current in the system does not exceed the normal current, INORMAL, by the predetermined current amount, and (ii) a current energized state, when the current in the system has exceeded the normal current, INORMAL, by the predetermined current amount; and (b) a parallel combination of (i) a first circuit switch, coupled with the current sensing means, wherein the first circuit switch is (ia) closed when the current sensing means is in the current deenergized state, and (ib) open when the current sensing means is in the current energized state, (ii) a voltage sensing means having (iia) a voltage deenergized state when the voltage across the voltage sensing means does not exceed a predetermined voltage amount, and (iib) a voltage energized state when the voltage across the voltage sensing means exceeds the predetermined voltage amount, and (iii) a PTC device; the circuit interruption element changing from its normal state to its fault state, thereby causing the system to change from its normal operating condition to its fault condition, when the resistance of the control element has increased by the predetermined resistance amount.