保护接地和保护接零是防止间接接触电击的基本技术措施,其中保护接零系统称为TN系统,包括TN-S, TN-C-S,TN-C三种方式,下列电气保护系统图中,属于TN
A <img src="https://www.beizhujiaoyu.com/uploads/202208/160671491726691.png" alt="" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/160671492917041.png" alt="" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/160671494875731.png" alt="" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/160671496126341.png" alt="" />