Problems in the installation and operation of lightning arresters for distribution transformers

There are many problems in the installation and operation management of lightning arresters for distribution transformers, and accidents such as users burning down transformers and bursting arresters often occur. For a long time, lightning arresters have been installed on the upper side of the high-voltage fuse of the distribution transformer. According to the operation comparison, this installation method is not reasonable.

1　Surge arrester installation

1.1 　 Existing problems and solutions

The lightning arrester is generally installed on the upper side of the high-voltage fuse. According to the regulations: "The height of the base of the substation shall not be less than 2.5m from the ground." In this way, when the arrester is damaged or causes grounding, short circuit, calibration and replacement, the entire 10kV line needs to be powered off, and It is not conducive to assembly and disassembly. In addition, the ground lead of the arrester is too long from the ground, which does not meet the relevant technical requirements. In view of the above problems, we changed the installation position of the distribution transformer arrester and installed it on the lower side of the high-voltage fuse. This will not affect the protection effect and scope of the arrester, but also facilitate the normal assembly and disassembly of the arrester, reducing the number of power outages across the entire line. At the same time, when the performance of the arrester is degraded and subjected to lightning, the power frequency freewheeling will increase, which will inevitably cause the arrester itself to malfunction, and the distribution transformer fuse will blow, which will isolate the fault point, reduce the chance of single-phase grounding or short circuit tripping, and improve power supply Reliability rate.

1.2 　 Installation precautions

The distance between the installation point of the arrester (arrester manufacturer) and the fuse should be greater than 0.7m to ensure that the safety distance specified in the "Electrical Safety Work Regulations" is met during maintenance. The lead length of the arrester should be as short as possible and the contact should be reliable. The wire should be 35～50mm2 black glue wire to reduce the lead reactance and reduce the residual voltage. The distance between the arrester and the transformer should be greater than 2m, increase the inductance on the wire, and improve the relative lightning resistance level of the transformer. When the arrester is removed and then installed, it should not be bound with iron wires, wires, etc., but should be re-installed with special fixtures to prevent creepage. In addition, the down conductor of the arrester must be connected well and tied to the cross arm and pole to prevent accidents such as grounding, short circuit or damage to the transformer when the arrester explodes.

2　Problems in the operation of the arrester

2.1　Due to damage, breakdown and corrosion, it is not easy to install, the source of funds and the burden of costs are difficult, and the village electrician's sense of responsibility is not strong, there are factors such as fluke psychology, etc., cannot be installed and supplemented in time, which objectively leads to the low installation rate and installation Not enough.

2.2 　 Due to the heavy workload of periodic inspection of arresters, a considerable number of arresters have not been verified for many years, and the arresters that have lost their function are still running online.

2.3 　 Due to the weak sense of responsibility of construction, installation, and maintenance personnel, most of the lightning arresters in operation have various abnormal conditions such as loosening, tilting, incorrect installation position, and lead wire falling off.

2.4　The product quality of lightning arrester is low and cannot effectively protect it.

2.5　The grounding down conductor is broken and twisted, and some even use iron wire instead of the grounding down conductor, and most of them have the problem of too large grounding resistance.

3　How to rectify

3.1 　 Increase publicity and education to let users understand the necessity and importance of installing lightning arresters.

3.2　 enable electricians to master the installation process of arresters, standardize construction, and leave no sequelae.

3.3 　 Strengthen the operation and management work, conduct regular inspections, inspections, and verifications. Unqualified arresters cannot be operated online.

3.4” Actively promote the use of zinc oxide arresters.

3.5 　 Conduct a careful inspection of the arrester grounding body and transformer grounding body of all distribution transformers in the jurisdiction, and thoroughly deal with the excessive grounding resistance.

Yichang Hengyuan Technology Co., Ltd. is a professional manufacturer of European-style cable connectors, plug connectors, cable branch boxes, American elbow connectors, high-voltage vacuum circuit breakers, high-voltage load switches, lightning arresters, zinc oxide arresters, tank arresters, overvoltage protectors, Counters, monitors, heat-shrinkable cable accessories, cold-shrinkable cable accessories, T-shaped heads, wall bushings, European cable accessories, American cable connectors, transformer neutral point protection devices, fuses, isolation switches, PT cable heads, elbows Manufacturers of type cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products