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US 3,944,845 AGranted
Liquid level shutoff control
OwnerFrank Kenneth Luteraninventor
Life of this patent
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Abstract
A liquid level shutoff control for minimum level control of conductive fluids. A pair of electrodes are disposed in the liquid at the minimum level desired for the fluid. The electrodes provide a conductive path for a high frequency electrical signal and circuits energize a controlled load such as a liquid heating or mixing apparatus whenever the electrodes are in contact with the fluid. Failure of the control circuit results in shut off of the controlled load thereby providing fail-safe minimum level control.
Claims9
A system for energizing a load from a power line when the level of a conductive liquid is above a preset point comprising:
- a. electrical energy means producing a D.C. voltage and an A.C. voltage from the power line,
- b. signal generating means connected to the electrical energy means and in response to the D.C. voltage applied thereto producing a high frequency signal,
- c. an input conductive probe contacting the liquid and coupled to the signal generating means,
- d. an output conductive probe contacting the liquid and providing a conductive path for the high frequency signal from the input conductive probe through the liquid to the output conductive probe,
- e. switching means coupled to the electrical energy means and to the output conductive probe for connecting the load across the A.C. voltage whenever conduction of the high frequency signal occurs from the input conductive probe to the output conductive probe.
2 more elements
Dependencies are inferred from the claim text.