IEC反时限曲线热效应分析及其在电机保护中的应用

Analysis of Thermal Effect of IEC Inverse Time Curve and Its Application In Motor Protection

对常见的三种IEC曲线进行了简单介绍,并通过可视化图表对相关曲线动作特点及保护动作时产生的热效应变化趋势进行了直观展示,揭示了该曲线在限制故障电流热效应方面存在的不足。提出了一种选取两条曲线的优化应用的方法,采用该方法通过设置合理的参数,能够避免采用单条曲线的缺点,达到有益的效果。最后,通过一台电机过电流保护工程应用实例,介绍了曲线组合应用时,相关参数的计算方法,并对采用该方法由故障电流产生的热效应进行了校验。通过工程实例计算表明,该方法能将故障电流造成的热效应限制在电机可承受的范围,避免故障电流对被保护电机造成进一步损坏,能达到良好效果。该方法在对其他的电气设备保护方面,也同样具有工程应用价值。

This article briefly introduces three common IEC curves,visualizes the rel⁃evant curve action characteristics and the trend of thermal effect generated during protection action through visual charts,reveals the shortcomings of the curve in limiting the thermal ef⁃fect of fault current.An optimized application method of selecting two curves is proposed,and the disadvantages of using a single curve can be avoided by setting reasonable param⁃eters to achieve beneficial effects.Finally,through a motor overcurrent protection engineer⁃ing application,the calculation method of the relevant parameters when the curves are com⁃bined and applied is introduced,the thermal effect generated by the fault current using this method is calibrated as well.Calculations from engineering examples show that the method can limit the thermal effect caused by the fault current to a tolerable range of the motor and avoid further damage to the protected motor.The method also has application value in the protection of other electrical equipment.