In order to determine the fault line, the traditional method is to pull the gate one by one, so as to select the fault line and judge the fault location. This method consumes time and reduces the reliability of power supply. Moreover, many times of closing and opening will have impact on the power system and main transformer, and using the switch repeatedly will reduce its service life. In order to solve this problem in time, the small current grounding line selection device is installed.

There are also a lot of matters needing attention in the field installation and use of the small current grounding line selection device. If you do not pay attention to it, it may lead to disaster. As a standardized configuration, the selection of equipment should be determined according to the actual situation on site, and the small current grounding system should be treated strictly.

The characteristics of zero sequence current transformer on the same site are basically the same, so the zero sequence current transformer matching with the company should be selected.

The polarity of all zero sequence current transformers must be strictly consistent, especially the site where zero sequence current transformer and three-phase current transformer are mixed. For systems with more than two busbars, the polarity of current transformers of all incoming devices must be consistent.

The zero sequence current transformer is generally installed under the cable head: the cable sheath grounding wire above the zero sequence transformer must be grounded at the line side after passing through the current transformer; the cable skin grounding under the zero sequence transformer cannot pass through the zero sequence transformer to avoid the formation of short circuit loop.

A large current transformer must be installed as an outgoing lead-in device for the line with double or multi cable power supply.

For all systems with cable outgoing lines, a zero sequence transformer and a secondary line grounding device are installed on each outgoing line. The polarity of current transformer must be consistent.

Under the condition of ensuring the normal operation of the device, the system simulation grounding debugging must be done. In the next article, the small editor will explain the analog grounding debugging method of small current grounding line selection device.