| 摘要 |
An alarm switch has a box for mounting on a supporting surface, a front plate movably mounted in the box, a frangible element having a plurality of frangible areas spaced in succession thereon and each of which can be broken off the frangible elements, a stop element on either the box or the front plate, and the frangible element being on the remaining one of the box and the front plate, the stop element and the frangible element being positioned for, when the front plate is moved from a normal position relative to the box, the stop element and one of the frangible areas are engaged for causing the frangible area to be broken off the frangible element, and the frangible element and the stop element being shiftable relative to each other for, after one frangible area has been broken off, bringing the stop element and the next frangible area in succession into position for being engaged with each other when the front plate is moved again, and a switch unit operatively connected to the front plate for being operated when the front plate is moved sufficiently far from the normal position to cause a frangible area to be broken off the frangible element.
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