矿用隔爆兼本安型软启动器过流拒动分析

Analysis on over-current refusal of mine explosion-proof and intrinsically safe soft starter

为了查找主排水泵的驱动电机(下称电机)定子绕组启动中烧损原因并制定相应防范措施,通过对控制主排水泵的交流软启动器和启动器上级的高压真空配电装置的速断与过流保护动作定值的比对,剖析出启动器启动方式设定为电压斜坡方式致使电机启动电流大于设定为电流斜坡启动方式时的启动电流,长时运行后导致电机定子绕组烧损。启动器保护级别设定为重载,造成电机故障电流相同时启动器的过流脱扣用时较长。该过流脱扣用时较长与高压开关的过流与速断保护动作定值设定偏小是电机定子绕组烧损时启动器过流保护拒动的真实原因。短路容量较小的供电系统保护装置速断保护定值的选定依据是高(低)压两相短路电流的公式算法,控制泵(风机)类负载的启动器宜选用电流斜坡启动方式、其保护级别与负载现场匹配是启动器现场技术管理务必重视的要点。利用三相交流电动机启动状态等效电路概算电机定子绕组启动中短路电流特定值,为启动器速断保护校验提供例证。

In order to find the main cause of the burning during the stator winding′s start-up that is in the drive motors(hereinafter referred to as the motor)of the main sump pump and find the solution,by comparing the value of instantaneous trip protection and overcurrent protection between AC soft starter(hereinafter referred to as the starter)controlling the main sump pump and the high-vacuum electric distributor(hereinafter referred to as the high-voltage switch),the author concluded that the starting current in the ramp voltage starting mode is bigger than in the ramp current starting mode,which causes the stator winding of the motor to burn out after long-term operation.The protection level is set as heavy-load,the time of overcurrent releasing would be long when the current is same and the motor is in trouble.The longer overcurrent releasing time and the smeller setting value of the instantaneous trip protection and overcurrent protection are the real reasons for the starter′s over-current protection refusing to operate when the motor stator winding is burnt out.The instantaneous trip protection setting value of power supply system protection device with small short-circuit capacity is selected as the formula algorithm,the camp current starting mode should be selected for the starters loaded with control pumps(fan),and the matching of the starters′protection level and the loading fact must paying attention in the starter field technical management.Calculating the instantaneous trip setting value during the stator winding start-up using the equivalent circuit of three-phase AC motor′s startup state provides an example for the verification of the starters′instantaneous trip protection.