Raychem Limited

Tyco Electronics Corporation

Brian Thomas

Hugh Duffy

Adrian I Cogan

James J Toth

Neill Thornton

Jiyuan Luan

Gilles Gozlan

Jean-Marc Beaufils

Bernard Dallemange

John A Midgley

Craig Wynn

Justin N Chiang

St Elmo Nickols, Iii

A protection circuit for use with a charger and a chargeable element, such as a rechargeable lithium ion battery, comprises a shunt regulator having a threshold ON voltage coupled in parallel across the chargeable element, and a temperature-dependent resistor, e.g., a positive temperature coefficient device, coupled in series between the charger and the chargeable element. The temperature dependent resistor is thermally and electrically coupled to the shunt regulator, wherein the first variable resistor limits current flowing through the shunt regulator if the current reaches a predetermined level less than that which would cause failure of the regulator, due to ohmic heating of the regulator.

Electrical device including a voltage regulator mounted on a variable resistor

Devices and methods for protection of rechargeable elements

A conventional ground fault circuit interrupter (GFCI) is modified to provide frequency-selective current protection. A control element is connected in series with the line path (or return path) of the GFCI, and a bypass element is connected in parallel with the combination of the control element and the line path (or return path) of the GFCI. Under normal conditions, little or no current flows through the bypass element. However, frequency response characteristics of the control and/or bypass elements are such that a frequency-selective component of the current (i.e. high-pass, low-pass or band-pass) is diverted through the bypass element. When the magnitude of the frequency-selective component reaches a predetermined value, the bypass current flow causes sensing of a resulting current imbalance and tripping of the GFCI.

Frequency-selective circuit protection arrangements

An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and which will preserve the trip endurance of a PTC device used in the protection system. The new system maintains the trip endurance of the PTC device by removing the source voltage from the PTC, while still keeping the circuit protection arrangement in a fault state, thereby continuing to protect the load.

Overcurrent protection circuit with improved PTC trip endurance

An electrical protection system which uses a ground fault interrupter (GFI) to protect a circuit from (A) ground faults and (B) overcurrents and/or overvoltages. For overcurrent protection, a control element may be coupled in series with the line or return input to the GFI, and a bypass element may be coupled in parallel with the control element and the GFI. In case of an overcurrent, the control element causes current to be diverted through the bypass element, thereby creating a current imbalance in the GFI circuitry causing the GFI to open the circuit. For overvoltage protection, a bypass element (e.g. a varistor) may be coupled between, e.g., the line sense input of the GFI and the return sense input of the GFI. In case of an overvoltage, the bypass element conducts current, thereby creating a current imbalance in the GFI circuitry causing the GFI to open the circuit.

Circuit protection arrangements using ground fault interrupter for

Overcurrent protection arrangements including a relay comprising two coils wound on a common magnetic core and a PTC device coupled in parallel with the relay contacts. The arrangement comprises a circuit interruption element which has a normal state which permits the flow of a normal circuit current, I.sub.NORMAL, to pass through the system, and a fault state which permits the flow of at most a reduced current, I.sub.REDUCED, substantially less than I.sub.NORMAL. A first control element is coupled in series between the power supply and the load, and is functionally linked to the circuit interruption element so that when the current through the first control element increases from I.sub.NORMAL to a relatively high current, I.sub.FAULT, the first control element can convert the circuit interruption element into the fault state. A second control element is coupled in parallel with the circuit interruption element, and is functionally linked to the circuit interruption element so that if the circuit interruption element is converted to the fault state, the second control element can cause the circuit interruption element to remain in the fault state as long as the current through the second control element is at least I.sub.REDUCED. The parallel combination of the circuit interruption element and second control element are coupled in series with the first control element. The relay contact functions as the circuit interruption element, and the two relay coils function as the first and second control elements.

Overcurrent protection device and arrangement

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, I.sub.NORMAL, 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 I.sub.NORMAL, 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, I.sub.NORMAL, 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, I.sub.NORMAL, 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.

Overcurrent protection circuit

An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and is particularly suitable for protecting circuits against relatively small overcurrents, comprising: a circuit interruption element which, in the operating circuit, is connected in series between the electrical power supply and the electrical load, and which has (1) a closed state which permits the flow of a normal current, I.sub.NORMAL, through the circuit interruption element, and (2) an open state which permits the flow of at most a reduced current, substantially less than I.sub.NORMAL, through the circuit interruption element; a control element which, in the operating circuit, is connected in parallel with the load, and which has (1)(i) an on state, when the voltage across the control element is a normal voltage, V.sub.NORMAL, and (ii) is converted to an off state, when the voltage across the control element falls to a value V.sub.FAULT, or less, and (2) is functionally linked to the circuit interruption element so that when the control element is in the on state, the circuit interruption element is in the closed state, and when the control element is in the off state, the circuit interruption element is in the open state; and a bypass element which (1) is connected in parallel with the circuit interruption element, and (2) has (i) a start-up state such that, if the circuit interruption element is in the fault state and a current I.sub.NORMAL is passed through the bypass element, the voltage across the control element is greater than V.sub.FAULT, and (ii) a stopped state such that if the circuit interruption element is in the fault state as a result of the voltage across the control element having fallen to a value V.sub.FAULT or less, the current through the bypass element is such that the voltage across the control element remains at a value of V.sub.FAULT or less.

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San Francisco, CA, United States of America

Brian Thomas