NTCF21大同市
对机械设备的伤害
全压直接起动时的起动转矩大约为额定转矩的2倍,这么大的力矩突然加在静止的机械设备上,会加速齿轮磨损甚至打齿、加速皮带磨损甚至拉断皮带、加速风叶疲劳甚至折断风叶等等。
软起动的转矩不会超过额定转矩,上述弊端可以克服。
当采用减压起动时,上述危害只有程度的降低;当采用软起动时,上述危害几乎消失;独立变压器供电方式直接起动只能在电网电压波动方面有所缓解,而其它方面的危害都照样存在。
超大型电动机的价值都很高,在生产中也都起着核心作用。它的一点故障便会造成很大的经济损失,对它采用完善的保护是非常必要的。比如说对一台电机我们不能指望它的各处绝缘都是一致的,可能在某一点就有个薄弱环节,出厂试验时它能通过,但在长时间的冲击下这个薄弱环节会逐渐首先显露出来,使其寿命缩短。如果我们采取软起动,则可以大大延长电机的使用寿命,这两种方案哪一个合算呢?这是显而易见的。
开关变压器
当今传动工程中常用的就是三相交流感应电动机。在许多场合中,由于其起动特性,这些电动机涌直接连接电源系统。如果直接在线起动,将会产生高达电机额定电流6倍的浪涌电流。该电流会使供电系统和串联的开关设备过载。如果直接起动,也会产生较高的峰值转矩,这种冲击不但会对驱动电动机产生冲击,而且也会使用机械装置受损。例如:辅助动力传送部(V形带,齿轮)。为了降低直动电流,应使用起动辅助装置,如起动用电抗器或自耦变压器,但使用电抗器或自耦变压器起动等常规方法只能逐步降低电压,而软起动器通过平滑升子电压,可以实现无冲击起动。因此,可以佳地保护电源系统以及电机。
HPMV中、高压软起动器是用多个可控硅串并联而成,可以满足不同的电流及电压要求,控制可控硅的触发角就可以控制输出电压的大小。当电机起动过程中,HPMV按照预先设定的起动曲线增加电机的端电压使电机平滑加速,从而减少了电机起动时对电网、电机本身、相连设备的电气及机械冲击。当电机达到正常转速后,旁路接触器接通。电机起动完毕后,HPMV软起动器继续监控电机并提供故障保护。在软停机时首先按照预先设定好的停机曲线平滑地降低电机的端电压直到电机停机。软停可以解决突然停机引起的水泵水锤现象及机械冲击等相关问题。
HPMV中、高软起动器的操作过程可以分为四过程:起动准备完成、起动过程、运行和停机过程。CPU对所有的过程都提供的保护。
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