| 摘要 |
A solid-state control circuit for selectively operating a deep fat fryer in a normal cook mode, a lower temperature hold mode, a fat melt mode and a safety thermostat test mode. During operation in the cook mode, a reference bias voltage is coupled to one input of a voltage comparator, and an operating bias voltage dependent on the temperature control setting and the actual cooking fat temperature sensed by a NTC resistive sensor is coupled to a second input of the comparator such that the comparator is effective to enable heating elements in the cooking fat when the fat temperature drops below the preset level. After a predetermined time interval during which the fryer is not being used, a timing circuit acts to vary the reference bias voltage and the operating bias voltage supplied to the comparator and thereby reduce the temperature of the fat to the lower preset hold mode temperature. A second comparator resets the timing circuit during the predetermined time interval if there is a demand for heat such as when frozen foodstuffs are placed in the cooking fat. In the melt mode, the timing circuit controls the first comparator such that the heating elements are cycled on and off to melt solidified cooking fat without scorching, and in the test mode, the temperature control potentiometer is bypassed to cause the first comparator to enable the heating elements to safely heat the cooking fat to a temperature where the safety thermostat and the safety contactor should function.
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