Problems existing in the installation and operation of distribution transformer arresters
There are many problems in the installation and operation management of distribution transformer arresters. Accidents such as users burning the transformer and bursting the arrester often occur. For a long time, arresters have been mostly installed on the upper side of the high-voltage fuse of distribution transformers. According to operational comparison, this installation method is not reasonable.
1. Lightning arrester installation
1.1 Problems and solutions
The arrester is generally installed on the upper side of the high-voltage fuse. According to the regulations: "The height of the transformer base from the ground shall not be less than 2.5m." In this way, when the arrester is damaged or causes grounding, short circuit, calibration and replacement, the entire 10kV line will be powered off, and it is not conducive to installation and disassembly. In addition, the ground lead of the arrester is too long from the ground and 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 does not affect the protection effect and range of the arrester, but also facilitates the normal assembly and disassembly of the arrester, reducing the number of power outages on the entire line. At the same time, when the performance of the arrester decreases and is struck by lightning, the power frequency freewheeling increases, which will inevitably cause the arrester itself to malfunction and the distribution transformer fuse to blow, which plays the role of isolating the fault point, reducing the chance of single-phase grounding or short-circuit tripping of the line, and improving power supply reliability.
1.2 Installation precautions
The installation point of the arrester (arrester manufacturer) should be greater than 0.7m away from the fuse to ensure that the safety distance specified in the "Safe Work Regulations for the Electrical Industry" is met during maintenance. The lead length of the arrester should be as short as possible and the contact should be reliable. The conductor should use 35~50mm2 black glue wire to reduce the lead reactance and reduce the residual voltage. The distance between the lightning arrester and the transformer should be greater than 2m to increase the inductance on the wire and improve the relative lightning resistance level of the transformer. When the arrester is removed and reinstalled, it cannot be tied with iron wires, wires, etc., but should be reinstalled with special clamps 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 grounding, short circuit or damage to the transformer caused by the explosion of the arrester.
2. Problems existing in the operation of arresters
2.1 Due to factors such as damage, breakdown, and corrosion that are difficult to install, sources of funds and cost burdens are difficult, and the village electricians have a weak sense of responsibility and a fluke mentality, they cannot install and replenish them in time, which objectively leads to a low installation rate and insufficient installation quantity of arresters.
2.2 Due to the heavy workload of regular calibration of arresters, a considerable number of arresters have not been calibrated for many years, resulting in ineffective arresters still operating online.
2.3 Due to the low sense of responsibility of construction, installation, and maintenance personnel, most arresters have various abnormal conditions such as loosening, tilting, incorrect installation positions, and lead wires falling off during operation.
2.4 The quality of lightning arrester products is low and cannot provide effective protection.
2.5 The grounding down conductor is broken or twisted, and some even use iron wire instead of the ground down conductor. In most cases, the grounding resistance is too high.
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 lightning arresters and standardize the construction without leaving any sequelae.
3.3 Strengthen operation management and conduct regular inspections, inspections, and verifications. Unqualified arresters cannot be operated online.
3.4 Actively promote the use of zinc oxide arresters.
3.5 Carefully check the lightning arrester grounding bodies and transformer grounding bodies of all distribution transformers in the jurisdiction. Those with high grounding resistance must be dealt with thoroughly.
Yichang Hengyuan Technology Co., Ltd. specializes in the production of European-style cable joints, plug-and-pull heads, cable branch boxes, American-style elbow joints, high-voltage vacuum circuit breakers, high-voltage load switches, arresters, zinc oxide arresters, tank arresters, over-voltage protectors, counters, monitors, heat-shrinkable cable accessories, Manufacturer of cold shrink cable accessories, T-heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbow cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products
