High voltage transformer protection configuration how to implement in place?

1, Installed lightning protection, to prevent lightning over-voltage: distribution transformer lightning protection, the use of installed gapless metal oxide surge arrester as over-voltage protection, to prevent the high voltage line intrusion of high voltage lightning waves caused by the internal insulation of the transformer breaks down, resulting in a short circuit, and put an end to the occurrence of lightning damage accidents.

The use of lightning arrester protection distribution variable, one is to purchase through normal channels qualified products, installation and commissioning of the installation of the strict test to meet the operational requirements and then put into operation; the second is the operation of the equipment on a regular basis for preventive testing, for the leakage current value of more than the standard value of the unqualified products in a timely manner to be replaced; the third is a regular transformer grounding resistance test, 100KVA and above, the requirements of distribution transformer grounding resistance must be 4Ω or less, and the grounding resistance must be 4Ω or less, the grounding resistance must be 4Ω or less. Third, regular transformer grounding resistance testing, 100KVA and above distribution transformers require grounding resistance must be within 4Ω, 100KVA below the distribution transformer, require grounding resistance must be within 10Ω.

If the test value is not within the prescribed range, should take the extension of the grounding wire, increase the grounding body and physical, chemical and other measures to make it reach the prescribed value, April and July each year to carry out two times the grounding resistance of the re-test, to prevent the welding point of desoldering, the environment and other factors lead to grounding resistance exceeds the standard. If the transformer grounding resistance exceeds the standard, lightning current can not flow into the earth, but through the grounding line will be added to the distribution transformer low voltage voltage and then reverse boosting for high voltage, will be burned; four is the installation location should be appropriate, high-voltage surge arrester installed in the high voltage casing close to the transformer at the lead, try to minimize the chance of direct lightning intrusion into the transformer, low-voltage surge arrester mounted in the low voltage casing close to the transformer to Ensure that lightning waves invade the correct action before the distribution substation, according to the standard requirements of the electrical equipment installation code installation, to prevent blind installation and loss of the significance of protection.

2, the installation of fast-break, overcurrent protection, to ensure selective removal of fault lines: distribution substation short-circuit protection and overload protection by the installation of high-voltage side of the distribution substation fuse and low-voltage side of the leakage of the total protector (the device has a leakage protection and distribution substation low-voltage overcurrent protection) to achieve. In order to effectively protect the distribution substation, it is necessary to correctly select the fuse of the fuse (fuse, fuse, etc.) and the low voltage overcurrent protection value. The selection of high-voltage side fuses should be able to ensure that the transformer is fused when a short circuit occurs at the internal or external bushings. Fuse selection principles: (1) capacity in 100kVA and the following distribution transformer, high voltage fuse according to 2 ~ 2.5 times the rated current selection; (2) capacity in 100kVA above distribution transformer, high voltage fuse according to 1.5 ~ 2 times the rated current selection.

Low-voltage side leakage total protector overcurrent action value of 1.3 times the rated value of the low-voltage side of the distribution substation, distribution substation low-voltage branch line overcurrent protection should not be greater than the total protection of the overcurrent action value should be less than the rated current of the low-voltage side of the distribution substation, generally according to the amount of conductor load to choose the value of overcurrent, to ensure that in the various outgoing circuits in the event of a short-circuit or the output of load is too large, caused by the overload of the distribution substation can be acted in a timely manner, cut off the load and the fault lines, to achieve the purpose of protection of the distribution substation. To realize the purpose of protecting the distribution substation.

At the same time, it can meet the selectivity requirements of all levels of protection. Low-voltage branch circuit short-circuit fault, branch circuit action, leakage protector overcurrent protection does not act, low-voltage side of the total circuit fault or short-circuit, low-voltage side of the leakage protector overcurrent protection action, the high-voltage side of the melt should not melt; transformer internal fault short-circuit, high-voltage side of the melt melting, high-voltage line protection device should not be acted on the previous level of substation tripping, to ensure that the distribution network protection device correctly graded action. Distribution transformer high-voltage side fuse protection material must be equipped according to the standard, and resolutely put an end to the use of copper, aluminum and other metal conductors to replace the fuse fuse.