Strain gauge pump control switch

摘要

A control switch incorporates a solid state transducer, a strain gauge. The transducer responds to a local environmental condition, such as fluid level, or pressure and exhibits a parameter change which can be detected as an electrical output. Control circuits coupled to the transducer can sense the parameter change and switch a source of electrical energy to a load in response thereto.

主权项

1. A control system for an electric motor comprising:
a watertight housing; a vent tube with first and second ends, the first end is coupled to the housing and the second end extends away from the housing; an elongated, radially oriented a strain gauge carried in the housing; control circuits coupled to the strain gauge and responsive to an output of the strain gauge; a relay and an electronic switch coupled to and independently controlled by the control circuits; an electrical connector for a motor, the electrical connector for the motor having prongs and receptacles; the second end of the vent tube located adjacent to each of the electrical connector, an output from the relay, and an output from the electronic switch; the electronic switch and the relay are directly electrically connected in parallel between at least one of the prongs and at least one of the receptacles of the electrical connector for the motor; the control circuits, responsive to the output of the strain gauge, sequentially: (i). place the electronic switch into a conducting state to couple an electric motor start up, inrush current, without arcing, from the at least one prong, through the electronic switch, to the at least one receptacle to start the motor; and (ii). once the inrush current has subsided, changing the state of the relay to provide a closed contact pair that carries the motor current from the at least one prong, through the relay, to the at least one receptacle as an alternate, parallel path to operate the motor.