Electrical contactor having a double immersion sensing function

Electrical contactor (21;

• 121) which can be actuated by immersion in a liquid medium and comprises a casing (22;
• 122) which includes a liquid-tight compartment (23;
• 123) which contains an electronic circuit (24;
• 124) interposed between a DC power source (25;
• 125) and a power outlet (26;
• 126), the said circuit comprising at least one connection component (27;
• 127) which connects the source (25;
• 125) to the outlet (26;
• 126) only if a sufficient voltage is applied to it, the said compartment (23;
• 123) having an immersion-sensitive wall (29;
• 129) with an external face (30;
• 130) which is in direct contact with the liquid in which the contactor (21;
• 121) is immersed, characterized in that:
• i) the said electronic circuit (24;
• 124) includes a first pair of electrodes (31-32;
• 131-132), the free ends of which lie on the external face (30;
• 130) of the immersion wall (29;
• 129) and which thus constitute a variable resistor (R.sub.3 ;
• Re) whose resistance depends on the nature of the medium with which the wall is in contact;
• ii) the said electronic circuit (24;
• 124) includes a second pair of electrodes (33-34;
• 133-134). the free ends of which are connected to an element (35;
• 135) which is sensitive to the pressure applied to it and at least part of which lies on the external face (30;
• 130) of the said immersion wall (29;
• 129) so as to make the said electrodes sensitive to the pressure of the medium with which the said wall is in contact;
• iii) the said immersion-sensitive wall (29;
• 129) includes an aperture (47;
• 147) closed by a microporous membrane (48;
• 148) which is permeable to gases and impermeable to the said liquid medium;
• iv) the said electronic circuit (24;
• 124) delivers the sufficient voltage to the said connection component (27;
• 127) only if each pair of electrodes has identified an occurrence of a threshold, predetermined in respect of its operating parameters, being crossed.