讲解感应电压配电系统故障.docVIP

讲解感应电压配电系统故障 供配电系统故障的不同对电动机供电回路的影响也不一样,再起动处理的方法也应有区别。供配电系统故障分单相接地、两相短路、三相短路、对称及不对称等多种故障形式,但对电动机供电回路的影响主要取决于故障的时间及电压降低的幅度。我们常见的有以下三种情况: Power supply and distribution system fault of different effect on the motor power supply circuit is different also, restart processing methods also have difference. Power supply and distribution system of single-phase grounding fault points, two phase short circuit, three-phase short-circuit, symmetric and asymmetric fault in the form, but the motor power supply circuits mainly depends on the influence of the fault time and reduce the magnitude of the voltage. Our common has the following three conditions: 　　1.瞬时欠压(voltage sag)是瞬时的电压降低,而不是电压的消失,其过程分为电压降低与电压恢复两部分。供配电系统发生故障的瞬时,由于感应电动机转子的磁链不能突变,原有的电流将继续存在,并在定子绕组端子间感应电压。该感应电压并不立即下降,而且能保持相当长时间,此电压称为残余电压。由于残余电压的存在,如果电源断开后,很快又再次合闸,将出现较大的合闸冲击电流及冲击转矩,冲击大小由合闸瞬间电动机的残余电压大小及相位决定。 1. The instantaneous undervoltage (voltage sag) is the instantaneous voltage is reduced, rather than the disappearance of the voltage, the process is divided into two parts of the voltage and the voltage recovery. Transient of the failure of power supply and distribution system, due to the induction motor rotor flux linkage cannot mutation, the original current will continue to exist, and the stator winding induction voltage between terminals. The induced voltage is not immediately fall, but also can keep a long time, the voltage is called the residual voltage. Because of the existence of residual voltage if the power disconnect after closing again soon, there will be a great closing impact current and impact torque, impact by closing moment motor size is decided by the size of residual voltage and phase. 　　2.短时失压与瞬时欠压的区别在于残余电压是否消失。短时失压是电压降低至消失而后电压才恢复。产生的原因主要是继电保护时差配合等原因无法实现快速切除故障。故障发生瞬间,电动机的电流与转矩陡然增大,然后逐渐振荡衰减,而残余电压和转速也开始逐渐下降。电源恢复瞬间,电动机的电流与转矩也会迅速增大,然后逐渐振荡衰减,而转速也开始逐渐上升,经过短时的振荡后稳定在某一数值上。 2. The difference between the short-term pressure loss and the instantaneous undervoltage is whether the residual voltage. Lo