| 摘要 |
<p>Improvements which are characterized in that the sensor element is formed by a heat-activated switch, which comprises a fixed contact element and a movable contact element, the latter produced in at least one sector, with a special metal alloy with shape memory, in such a manner that it can pass from a first position in which it keeps the contact closed, and which is aided by the tightening of an elastic means, to a second, open situation, overcoming the pressure of the aforesaid elastic element, as a function of the adoption of a specific memorized and preformed configuration as a consequence of the heatingup of the aforesaid movable contact element as a result of an electric current being passed through it, when the level of the liquid drops below a preset value, in which part or all of the aforesaid movable contact element is uncovered.</p> |
