ABB 1SNA684252R0200工控DCS系统PLC模块

ABB 1SNA684252R0200工控DCS系统PLC模块

1.2.1利用电气接地网作为DCS接地网，即与电气接地网共地； 　

1.2.2设DCS系统独立的接地网； 　　

1.2.3设DCS接地网，经接地线、再接至电气接地网； 由于第三种接地方式与种接地方式有较多相同处，过去，计算机或DCS系统曾经较多的采用过的接地网。

但这种接地方式存在的缺点是：占地面积太大，投资高，电缆及接地网钢材耗量大，距厂房有相当的距离(因不易在厂房内找到合适的位置)，管理、维护、测量及查找接地极和接地线不方便，且效果不甚良好。根据实际运行表明，设置的DCS接地网是既困难又不安全的。如某电厂曾因接地问题，造成机组跳闸数十次。根据调查，不少电厂DCS后来改用电气接地网接地，取得了良好的效果。

1.2.1 Use the electrical grounding network as the DCS grounding network, that is, common ground with the electrical grounding network;

1.2.2 Set an independent grounding network for DCS system;

1.2.3 Set DCS grounding network, through the ground wire, and then connect to the electrical grounding network; Because the third grounding method has more in common with the first grounding method, in the past, the computer or DCS system has used more grounding networks.

However, the disadvantages of this grounding method are: the floor area is too large, the investment is high, the cable and grounding network steel consumption is large, there is a considerable distance from the plant (because it is not easy to find the right location in the plant), the management, maintenance, measurement and search for the grounding pole and the grounding wire is not convenient, and the effect is not very good. According to the actual operation, the DCS grounding network is not only difficult but also unsafe. For example, a power plant has caused dozens of unit trips due to grounding problems. According to the survey, many power plant DCS later switched to electrical grounding network grounding, and achieved good results.