Substation grounding issues

The last edit to this post was made by zhaohh3211 on 2010-11-17 at 14:47. In a TN-S system, the central grounding point should be connected to the grounding bar near the transformer or distribution room, while protective grounding must be provided near the equipment; this is what enables repeated grounding. In other words, the two systems are independent of each other. What you’re suggesting is to connect them directly, which would mean there would be no protective grounding – that’s how I understand it.

This post was last edited by zhaohh3211 on 2010-11-17 at 14:42. You can search on Baidu for Professor Ren Huiyuan’s video lectures on registered electrical engineers; the explanations in those lectures are very clear.

How should the protective grounding and working grounding be implemented in a TN-S system? Is it possible to use a single lightning protection grounding conductor? Both the transformer neutral point and the protective grounding of the distribution cabinet enclosure can be connected to the grounding electrode. The transformer neutral point is then connected to the neutral wire at the distribution cabinet, with insulators used to isolate it from the cabinet; this serves as the working neutral wire. (Note that the transformer neutral point should be grounded at only one point.) The protective grounding of the enclosure can be grounded at multiple points

In TN-S systems, the system neutral point is grounded, the equipment enclosures are connected to zero and then further grounded, and the neutral and ground wires are separate from the equipment. I completely agree with what was said above: it is possible to share the lightning protection grounding system, while the equipment grounding can also be handled independently before being connected to the grounding grid.

You can do the following: A grounding grid should be installed around the substation, designed and constructed in accordance with relevant standards, forming a network in a grid pattern. At least two grounding wires should be led out from different locations, and a grounding busbar box should be installed at a height of 500–600 millimeters above the ground and connected to this grid. Connect the transformer neutral point to the grounding busbar. Connect the copper busbars for the three-phase power and neutral wire inside the distribution panel to the R, S, T, N busbars of the transformer. The grounding busbar of the distribution panel is connected to the underground grounding busbar of the substation using flexible wires; it is also advisable to connect it to the grounding point of the transformer’s neutral wire. In the distribution panel, the N busbar and the E busbar are separated; the N busbar is supported by insulators. The enclosure of the distribution panel is grounded for overall connection, and it is connected to the grounding busbar via flexible wires. The TN-S system is the three-phase five-wire system, where the working neutral wire and the protective neutral wire are separated. It is particularly important to distinguish between protective neutral connection and protective grounding; the protective neutral wire is also connected to ground, and just because it is grounded it does not mean it is considered protective grounding. Don’t make a mess.