一起三相异步电动机缺相问题的分析

据统计，三相异步电动机绕组烧毁事故，大多是由于电动机缺相运行造成的。但由于大家对缺相问题的认识不足，只是依靠热继电器来对电动机进行保护，无法对电动机提供有效的缺相保护。对三相异步电动机在缺相工况下的故障电流进行分析，给出其变化趋势。结合某厂实际，对配电回路中常规保护装置不动作的原因进行深入分析，给出合理的解释，并提供解决缺相问题的方法。通过在配电回路中增加缺相保护装置，有效地减少了该厂电动机损坏事故。

Analysis on an Open-Phase Fault of Three-Phase Asynchronous Motor

Statistics show that the burning of winding of three-phase asynchronous motors is mainly caused by the open-phase fault. However, due to lack of understanding of the open-phase fault, we only use thermal relays to protect the motor, therefore unable to provide effective protection for the motor. This paper analyzes the fault current of the three-phase asynchronous motor under the open phase condition and gives the variation trend. Based on the practical situation of our plant, an in-depth analysis is made on the causes of inaction of the conventional protection device in the distribution circuit, with the reasonable explanation given and solution for the open phase problem provided. Motor protection can be achieved by adding open phase protection devices to reduce motor accidents effectively.