| 摘要 |
An advance warning control system for controlling the liquid level in a heating tank including an electrical immersion heater to provide a source of radiant energy, a control means operably associated with the immersion heater and the control means including a first normally open bi-metallic switch and a second normally closed bi-metallic switch which together operate to provide an advance warning upon energization of the first switch to give a predetermined time interval before energization of the second switch.
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