IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0490585
(2012-06-07)
|
등록번호 |
US-8614868
(2013-12-24)
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발명자
/ 주소 |
- Lawler, Robert
- Barber, John P.
- Ykema, John I.
|
출원인 / 주소 |
- SPD Electrical Systems, Inc.
|
대리인 / 주소 |
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인용정보 |
피인용 횟수 :
0 인용 특허 :
10 |
초록
▼
A circuit fault detector and interrupter which consists of parallel current conduction paths, including a path through a mechanical contactor and a path through a power electronics switch having active feedback control. A fault can be detected by a fault detection circuit within 50 μS of the occurre
A circuit fault detector and interrupter which consists of parallel current conduction paths, including a path through a mechanical contactor and a path through a power electronics switch having active feedback control. A fault can be detected by a fault detection circuit within 50 μS of the occurrence of the fault, causing the mechanical contactor to be opened and the fault current to be commutated via a laminated, low-inductance bus through the power electronics switch. The power electronics switch is thereafter turned off as soon as possible, interrupting the fault current and absorbing the inductive energy in the circuit. The fault current can be interrupted within 200 microseconds of the occurrence of the fault, and the device reduces or eliminates arcing when the mechanical contactor is opened.
대표청구항
▼
1. A circuit interrupting device having a graded resistance current path comprising: a. a first current path, traversing a mechanical contactor;b. a second current path, parallel to said first current path, said second current path comprising a resistance network of two or more switched, parallel re
1. A circuit interrupting device having a graded resistance current path comprising: a. a first current path, traversing a mechanical contactor;b. a second current path, parallel to said first current path, said second current path comprising a resistance network of two or more switched, parallel resistance stages; andc. fault detection circuitry, for detecting a fault condition and producing a fault signal;wherein a fault current is commutated from said first current path to said second current path upon detection of said fault current by opening said mechanical contactor; and furtherwherein each stage of said resistance network is sequentially switched out of said network, until an open circuit condition exists, thereby changing the overall resistance of said resistance network as each stage is switched. 2. The circuit interrupting device of claim 1 wherein each of said resistance stages in said resistance network comprises a resistance and a switch and wherein said switch is closed in the absence of said fault signal. 3. The circuit interrupting device of claim 2 wherein said switch is electronically controllable. 4. The circuit interrupting device of claim 3 further comprising a controller, responsive to said fault signal, for controlling said switches in each of said resistance stages in said resistance network. 5. The circuit interrupting device of claim 4 wherein said controller opens each switch in said resistance stages in said resistance network at timed intervals after receiving said fault signal, thereby sequentially removing each resistance stage from said resistance network. 6. The circuit interrupting device of claim 1 wherein the overall resistance of said resistance network is controlled such that the voltage drop across said resistance network the does not exceed the voltage withstand of said mechanical contactor at any time between the detection of said fault condition and the time at which all stages have been removed from said resistance network. 7. The circuit interrupting device of claim 6 wherein said resistance value in each of said resistance stages is higher than in the previous stage and further wherein said resistance stages are remove in order from lowest to highest, such that the overall resistance of said resistance network increases as each stage is remove from said resistance network. 8. The circuit interrupting device of claim 6 where said mechanical contactor comprises: a. a stationary contact;b. a moveable contact; andc. a Thompson coil that, when energized, forces said movable contact away from said stationary contact. 9. The circuit interrupting device of claim 8 wherein the voltage withstand voltage of said mechanical contactor increases as said moveable contact moves away from said stationary contact. 10. The circuit interrupting device of claim 4 wherein said controller is selected from a group consisting of a programmable analog circuit, a field programmable gate array and an application specific integrated circuit. 11. The circuit interrupting device of claim 1 wherein said fault detection circuitry comprises: a current detector;a high gain, narrow bandwidth integrator, coupled to the output of said current detector; anda first level detection circuit, coupled to the output of said narrow bandwidth integrator, for producing a fault signal when a fault condition is detected. 12. The circuit interrupting device of claim 11 wherein said fault signal is produced when the response of said narrow bandwidth integrator exceeds a predetermined level. 13. The circuit interrupting device of claim 12 wherein said narrow bandwidth integrator produces a response to line frequency current that is below said predetermined level. 14. The circuit interrupting device of claim 11 further comprising: a low gain, wide bandwidth integrator for sensing line frequency current; anda second level detection circuit, coupled to the output of said wide bandwidth integrator, for sensing line frequency current and for producing a fault signal when a fault condition is detected. 15. The circuit interrupting device of claim 14 wherein said fault signal is produced when the response of said wide bandwidth integrator exceeds a predetermined level. 16. The circuit interrupting device of claim 11 wherein said current detector is a Rogowski Coil. 17. The circuit interrupting device of claim 2 wherein said switches are IGBTs. 18. A method for handling an electrical fault comprising the steps of: a. detecting said fault using a fault detection circuitry, said fault detection circuitry producing a fault signal;b. opening a mechanical contactor having a stationary contact and a moving contact by forcing said moving contact away from said stationary contact in response to said fault signal;c. providing a secondary, parallel path to handle current flow as said mechanical contactor is opened, said secondary path being a resistance network having a plurality of parallel, switched resistance stages; andd. sequentially opening said switch in each of said resistance stages at staged intervals, thereby increasing the overall resistance of said resistance network at each interval, until said secondary path is an open circuit. 19. The method of claim 18 wherein the voltage drop across said resistance network is never allowed to exceed a voltage which would cause arcing across said mechanical contactor. 20. The method of claim 18 wherein said switches in each stage of said resistance network are controlled by a programmed controller responsive to said fault signal. 21. A circuit interrupting device having a graded resistance current path comprising: a. a first current path, traversing a mechanical contactor;b. a second current path, parallel to said first current path, said second current path comprising a resistance network of two or more switched, parallel resistance stages;c. fault detection circuitry, for detecting a fault condition; andd. a controller programmed, upon detection of said of said fault condition, to sequentially switch each stage of said resistance network out of said network, until an open circuit condition exists, thereby changing the overall resistance of said resistance network as each stage is switched;e. wherein said mechanical contactor is opened upon detection of said fault condition, thereby commutating current in the circuit from said first current path to said second current path.
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