|转至：电力合伙人
热继电器是用于电动机或其它电气设备、电气线路的过载保护的保护电器。以其体积小，结构简单、成本低等优点在生产中得到了广泛应用。
热继电器的工作原理是流入热元件的电流产生热量，使有不同膨胀系数的双金属片发生形变，当形变达到一定距离时，就推动连杆动作，使控制电路断开，从而使接触器失电，主电路断开，实现电动机的过载保护。
一、复位方式
热继电器一般有手动复位和自动复位两种方式，实际应用中，要根据具体情况来选择。
从控制电路的情况而言，采用按钮控制的手动启动和停止的控制电路，热继电器可以设为自动复位形式。采用自动元件控制的自动启动电路，可将热继电器设为手动复位方式。
对于重要设备和电动机过载的可能性比较大的的设备，热继电器动作后，需检查电动机与拖动设备，为了防止热继电器自动复位，此时宜采用手动复位方式。
二、热继电器电流的整定
对于星形/三角形控制运行设备，根据接线不同，有两种情况。
如图所示，热继电器的整定值与被保护电动机额定电流值基本相等。
如图所示，流过热继电器的电流值是相电流，因为三角形接法的电动机，线电流(即额定电流值)是相电流的√3倍，所以热继电器的整定值应为电动机额定电流的1/ √3倍约等于0.58倍。
因此，图二也可以直接设定电动机额定电流值。
专栏：行业资讯
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行业资讯
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