大型电力变压器低压侧绕组直流电阻测试新方法

DC resistance measurement for low voltage side windingof large-scale transformer

介绍了测量大型变压器低压侧绕组直流电阻的几种方法,详述和分析了其测试过程和测量结果,并针对现有测量方法测量低压侧绕组直流电阻时的不足,综合助磁法和全压-恒流电源法,提出了基于这2种方法的一种新方法。在电路强制稳态的基础上,开始加全压(高压)以迅速提高线圈电流,缩短过渡过程,然后用恒流源稳定电流进行测量;助磁法是把高、低压绕组串联起来,通电流测量,由于高压绕组的匝数远比低压绕组匝数多,借助于高压绕组的励磁安匝数,用较小的电流就可使铁芯饱和,从而使绕组电感大为减小,以缩短测试时间,而达到快速测试的目的。

Several DC resistance measurements for low voltage side winding of large- scale transformer are introduced,detailed in testing process and measuring results. A new method is proposed to improve present measuring methods,which is based on the full- voltage constant-current source method and the saturable magnetic circuit method. At forced stationary circuit state,full -voltage is used to quickly increase the winding current and shorten the transient process,and constant- current source is then achieved for measuring. With the high and low voltage windings connected in series ,because the turns of high- voltage windings are much more than those of low -voltage windings,a small going-through measuring current may make the iron core saturated,which reduces the winding inductance greatly and shortens the testing time.