GB1036127A - Improvements in or relating to snap action electric switches - Google Patents

Abstract

1,036,127. - Thermal switches. OTTER CONTROLS Ltd. March 15, 1963 [March 15, 1962], No. 10017/62. Heading H2B. A cut-out comprising a pre-stressed blade 1, which may be of bi-metal, having a central tongue 3 carrying a contact which is snapped out of engagement with a fixed contact (not shown), for example, when ambient temperature rises or current through the blade is excessive, is provided with a latch for retaining the contacts open until it is manually reset. In the form shown in Fig. 1 a spring arm 19 is biased to the position shown by broken lines but is normally retained in a crimped groove 15 in tongue 3. When tongue 3 snaps the contacts open, arm 19 is released from groove 15 and moves to its broken-line position wherein it prevents the contacts being reclosed (Fig. 3, not shown). The end of arm 19 engages in a slot 20 in the end of a reset plunger 13, depression of which moves arm 19 back into the groove 15 and allows the contacts to reclose. In the embodiment of Fig. 5 (not shown) the latch is formed by an arm 22 normally urged against a small flange 24 at the end of tongue 3. When the contacts (not shown) are opened by snapping of tongue 3, the arm 22 moves across the end of the tongue to prevent it restoring until the plunger 13 is pressed to return arm 22 to the solid line position.