| 摘要 |
<p>An electric circuit breaker for household and similar applications is of such a construction that a substantial proportion of its components are standard for the preferred current ratings of the breaker and that some components having a limited useful life can be readily replaced. The circuit breaker comprises a switching unit 11 comprising a moulded case 12 housing fixed and movable contacts 13, 14, a tripping mechanism 15 and a manually operable dolly switch; an over-current release unit 21 comprising a moulded case 22, separately formed with respect to the case 12 of the switching unit 11, housing an electromagnetic device 23 operatively mechanically coupled to the tripping mechanism 15 and adapted to be electrically interconnected in a power circuit 5 independent of the power circuit 4 to be protected and current sensing means 26 for continuously providing an output signal which is a function of the current flowing through the circuit to be protected, said units being so detachably electrically connected that current which will flow through the circuit to be protected will flow through the switching unit; and, electrically connected to the current sensing means, a microprocessor 31. The microprocessor 31 can be so programmed that, in the event of a short circuit or sustained overload, a current is caused to flow through the independent power circuit 5 to operate the electromagnetic device 23 and thereby initiate operation of the tripping mechanism 15 of the switching unit 11.</p> |
