| 电力变压器铁心接地故障原因 |
| 添加时间：2019/4/29 16:57:46 浏览次数： |
| 变压器的铁心接地有如下三种方式： There are three ways of grounding transformer cores: ①铁心与金属结构件均通过油箱可靠接地； The core and the metal structure parts are grounded reliably through the oil tank. ②铁心通过套管从油箱上部引出可靠接地，结构件通过油箱可靠接地； The core can be reliably grounded from the upper part of the tank through the casing, and the structural parts can be reliably grounded through the tank. ③铁心和结构件分别通过套管从油箱上部引出可靠接地（铁心垫脚与油箱底间铺有纸板）。 (3) Reliable grounding of the core and structural parts is induced from the upper part of the tank through casing respectively (cardboard is laid between the core foot and the bottom of the tank). 每台变压器采用哪种接地方式，由国家标准及运行部门需要决定，一般对高电压大容量变压器通常采用第三种方式，较小容量较低电压者采用第二种，小容量低电压者采用第一种。 The grounding mode of each transformer is decided by national standards and operation departments. Generally, the third mode is used for high voltage and large capacity transformers, the second mode is used for low capacity and low voltage transformers, and the first mode is used for small capacity and low voltage transformers. 第一种接地方式，无法在油箱外检查铁心是否有多点接地故障，只能通过较长时间的空载运行，由油中气相色谱分析来进行判断。 The first grounding method can not check whether the core has multi-point grounding fault outside the oil tank. It can only be judged by gas chromatography analysis in oil after a long period of no-load operation. 第二种接地方式，可以通过铁心引至油箱上部的接地套管引线（拆除接地线后），测量其对油箱间的绝缘电阻来判断铁心是否多点接地，但无法判断是否与结构件间存在多点接地。 The second grounding method can determine whether the core is grounded at multiple points by measuring its insulation resistance to the upper grounding casing lead (after removing the grounding wire), but it is impossible to judge whether there is a multi-point grounding between the core and the structural parts. 第三种接地方式，可以通过铁心和结构件引至油箱上部的接地套管引线，分别测量其对油箱及相互之间的绝缘电阻，来判断铁心和钢夹件间是否连通。 The third grounding method can determine whether the core is connected with the steel clamp by measuring the insulation resistance of the grounding sleeve lead to the upper part of the tank through the core and structural parts. 在油箱底部存有金属异物是构成铁心多点接地的主要原因之一，而这些异物大都是在制造或大修过程中遗存的。一般，可有四种金属异物残存： The presence of metal foreign bodies at the bottom of the tank is one of the main reasons for the multi-point grounding of the core, and most of these foreign bodies are left in the process of manufacture or overhaul. Generally, there are four kinds of metal foreign bodies remaining: ①粒状（焊渣）沉积物附着在铁心硅钢片与结构件间的绝缘上，形成金属性多点连通； (1) The granular (welding slag) deposits are attached to the insulation between the core silicon steel sheet and the structural parts, forming a metal multi-point connection; ②有较大的金属异物（焊条头、铁屑、钢丝绳断头等）搭接在铁心硅钢片与结构件间形成通路； (2) There are larger metal foreign bodies (welding rod head, scrap, broken wire rope, etc.) overlapping to form a path between the core silicon steel sheet and the structural parts; ③铁丝或铁片等落于铁心下轭面与箱底间，不带电时沉积在油箱底部无多点接地反映，带电时铁心的磁性将这些异物吸引，在下铁轭面与油箱底间形成通道； (3) The iron wire or sheet falls between the lower yoke surface of the core and the bottom of the tank, and deposits at the bottom of the tank without multi-point grounding reflection when not www.huganqi.org.cn www.diandongmenq.cnwww.yanglaoyuanq.cnwww.luoganqibiji.com.cncharged. www.xiaoyuandiaos.com.cnwww.qinhuandaobaojie.cnWhen charged, the magnetism of the iron core attracts these foreign bodies and forms a channel between the lower yoke surface and the bottom of the tank. ④穿心螺杆绝缘破损或是与钢夹件间有金属异物连通，有时下铁轭的上端面与钢夹件间有金属异物桥接也可造成多点接地。 (4) Insulation breakage of threading screw or metal foreign body connection with steel clamp, sometimes metal foreign body bridge between upper end of lower yoke and steel clamp can also cause multi-point grounding. |
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