| 摘要 |
Electrically resistive liquids such as tap water are heated in an all solid state electrical apparatus. Spaced inner and outer conically shaped electrodes provide a flow path for the water or other liquid which is heated to a preselected temperature by selectively passing alternating current between the electrodes and through the partially conductive liquid. The resistivity of the liquid dissipates the electrical energy in the form of heat which thus increases the temperature of the flowing liquid. Rapid, safe and effective control over the electrical current flowing between the conical electrodes is achieved by an electrical control circuit including a solid state alternating current switching device, a current sensing circuit, a temperature sensing circuit and a logic circuit for selective control of the switching device. Predetermined conditions of the temperature and current sensing circuits cause the logic circuit to selectively trigger the solid state switching device into conduction for passing a sufficient number of half or full cycles of alternating current to the electrodes to achieve the desired temperature rise and steady state temperature level of the flowing liquid.
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