| 摘要 |
An electrical system which protects a circuit from overcurrents. The system includes a control element (6) connected in parallel with the load (8); a circuit interruption element (2); and a bypass element (4, 17, 19). A parallel combination of the circuit interruption and bypass elements is connected in series with the parallel combination of the electrical load and the control element. The circuit interruption element (2) has a closed state and an open state. The control element (6) has an on state, when the voltage across it is normal, and an off state, when the voltage across it falls to a value VFAULT, or less; and 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. The bypass element comprises a first bypass path (17, 4) and a second bypass path (19) in parallel with the first bypass path; and has a start-up state and a stopped state. In the start-up state, if the circuit interruption element is in the open state and a current INORMAL is passing through the bypass element, substantially all the current through the bypass element passes through the first bypass path, and the voltage across the control element is greater than VFAULT. In the stopped state, if the circuit interruption element is in the open state as a result of the voltage across the control element having fallen to a value VFAULT or less, substantially all the current through the bypass element passes through the second bypass path, and the current through the bypass element is such that the voltage across the control element remains at a value of VFAULT or less.
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