运行中港下变压器的铁芯及其他附件都处于绕组周围的电场内，如不接地，铁芯及其他附件必然感应一定的电压，在外加电压的作用下，当感应电压超过对地放电电压时，就会产生放电现象。为了避免变压器的内部放电，所以要将铁芯接地。

Under the operation in Hong Kong transformers and other accessories are in the field winding around, if not grounded, the iron core and other accessories must be induced, the role of the applied voltage, when the voltage over the discharge voltage to ground, will have a discharge phenomenon. In order to avoid the internal discharge of the transformer, the core must be grounded.