Should the neutral and ground wires of the UPS isolation transformer be connected?

Is the neutral grounded? ? What are you thinking? Absolutely must not answer! To be honest, I didn’t quite understand the specific description of the problem:P But it’s certain that the neutral wire must not be grounded.

In a TN-S system, if the UPS has an output isolation transformer, the 220V output has its neutral connected to ground, but it is not connected to the neutral on the input side (although both are conductive). For the 380V output, the neutral of its bypass isolation transformer must be grounded as well, without being connected to the neutral on the input side

Well, it seems I really didn’t understand the question. Then let me ask again: does the ground connected to the output side need to be from a different ground network than that of the input side?

For our chemical plant, it’s essentially all part of the same ground network. Experience has shown that if the neutral line and ground wire of the UPS are not properly connected, waveform distortion occurs, and some measuring devices cannot function properly

This post was last edited by myface on 2018-3-28 09:15. I found this: “2. The secondary side should remain independent, that is, it should not be connected to ground, nor to the protective conductor, nor to any other electrical circuit.” As shown in Figure 3–9, if the secondary side of the transformer is grounded, when a person suffers a single-phase electric shock on the secondary side, current can easily flow through the human body and the grounding point on the secondary side to form a circuit. Therefore, wherever electrical isolation is used as a safety measure, there must also be measures to prevent secondary circuit faults from causing grounding and short circuits to other circuits. Because once a ground fault occurs on the secondary side, this measure will completely lose its protective function. For secondary side circuits with long lengths, an insulation monitoring device should also be installed. " It seems what I found states that isolation transformers are used to convert TN systems into IT systems; isn’t this referring to a different type?

If an isolation transformer is used in IT systems, it must not be grounded in order to protect human safety. However, when an isolation transformer is used in UPS systems, it is intended to improve voltage quality; in such cases, failing to ground the load’s neutral wire will prevent the desired outcome from being achieved. GB 50303-2002 also sets relevant requirements in this regard