Are arresters composite insulators? Some people think that arresters are composite insulators, and composite insulators are also arresters, but the fact is that arresters and composite insulators are two different functional components.
The first thing to do is how to distinguish it.
(1) Look at the appearance design
Those with terminals are lightning arresters, and those without terminals are composite insulators.
(2) Function
On the other hand, the functions of the two components are also different. Composite insulators are devices arranged between conductors with different potential differences or between conductors and grounding components and can withstand voltage and mechanical stress. In transmission lines Play a role of support and traction.
The lightning arrester is a component connected between the grid wire and the ground wire. It plays a protective role. It also has an alias called an overvoltage protector. Therefore, through the appearance design, installation position, and function, it is possible to distinguish which is a composite insulator and which is a lightning arrester.
Lightning arresters can not only be used to protect the high voltage generated by lightning, but also can be used to protect and manipulate high voltage. The types of surge protectors mainly include protection gaps, valve-type surge protectors, and zinc oxide surge protectors.
The basic principle of the arrester is to protect the communication cable equipment. If there is an abnormal voltage, the arrester will trigger and play a protective role. The arrester will not cause any effect during normal operation. When the overvoltage disappears, the arrester will quickly return to normal, making the communication line normal. run.
Seven characteristics of zinc oxide arresters:
(1) flow capacity
This is mainly reflected in the arrester's ability to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages.
(2) Protection Characteristics
Zinc oxide arrester is an electrical product used to protect various electrical equipment in the power system from overvoltage damage, and has good protection performance. Because the nonlinear volt-ampere characteristics of the zinc oxide valve are very good, only a few hundred microamps of current flow through under the normal working voltage, which is convenient to design into a gapless structure, so that it has good protection performance, lightweight and small size. feature. When the overvoltage invades, the current flowing through the valve increases rapidly, and at the same time limits the amplitude of the overvoltage and releases the energy of the overvoltage. After that, the zinc oxide valve returns to the high-resistance state to make the power system work normally.
(3) Sealing performance
Arrester components adopt high-quality composite casing with good aging performance and good air tightness. Measures such as controlling the compression of the sealing ring and adding sealant are adopted. The ceramic casing is used as the sealing material to ensure reliable sealing and stable performance of the arrester. [4]
(4) Mechanical properties
The following three factors are mainly considered: the earthquake force withstood; the maximum wind pressure acting on the arrester; the maximum allowable tension of the conductor on the top of the arrester.
(5) Decontamination performance
The gapless zinc oxide arrester has high pollution resistance.
The specific creepage distance grades stipulated by the national standard are: Class II moderately polluted area: creepage specific distance 20mm/kV; Class III heavily polluted area: creepage specific distance 25mm/kV; Class IV extremely heavy polluted area: creepage specific distance 31mm/kV.
(6) High operational reliability
The reliability of long-term operation depends on the quality of the product and whether the selection of the product is reasonable. The quality of its products is mainly affected by the following three aspects: the rationality of the overall structure of the arrester; the volt-ampere characteristics and aging resistance of the zinc oxide valve plate; the sealing performance of the arrester.
(7) Power frequency tolerance
Due to various reasons in the power system, such as single-phase grounding, long-term capacitive effects, load shedding, etc., the power frequency voltage will increase or a transient overvoltage with a high amplitude will be generated. The arrester can withstand a certain power frequency within a certain period. Voltage boost capability.
Composite insulators are also a special type of insulation control. There are various types of composite insulators. Although there are big differences in the structure and appearance design of various types of composite insulators, they are all composed of two parts: insulating parts and connecting fittings. It is generally made of glass or ceramics. Composite insulators are different from lightning arresters. Composite insulators should not fail due to various electromechanical stresses caused by changes in the environment and electrical load conditions, otherwise composite insulators will not cause significant effects. , It will damage the service life and operation life of the whole line. Overall, composite insulators and arresters have their uses, and each is a significant component.
Editor's summary: After reading the above introduction, I believe that everyone has a better understanding of the difference between arresters and insulators. For more information, please continue to pay attention to our website, and we will present you with more exciting content in the future.