An electrical appliance used to protect electrical equipment from high transient overvoltage hazards and limit the follow-through time and often limit the follow-through amplitude. The arrester is usually connected between the grid conductor and the ground wire, but sometimes it is also connected next to the electrical winding or between the conductors. The arrester is sometimes also called an overvoltage protector. The arrester is another important device often used to prevent lightning damage to communication cables.

Lightning arrester: An electrical appliance used to protect electrical equipment from high transient overvoltage hazards during lightning strikes, and limit the follow-through time and often limit the follow-through amplitude. The arrester is sometimes also called an overvoltage protector or overvoltage limiter.

Scope of application

AC gapless metal oxide arresters are used to protect the insulation of AC power transmission and transformation equipment from lightning overvoltage and operating overvoltage damage. Applicable to overvoltage protection of transformers, transmission lines, distribution panels, switch cabinets, power meter boxes, vacuum switches, parallel compensation capacitors, rotating motors and semiconductor devices.

Features and Principles

AC gapless metal oxide arresters have excellent nonlinear volt-ampere characteristics, good response characteristics, no continuous flow, large current capacity, low residual voltage, strong overvoltage suppression ability, pollution resistance, anti-aging, no altitude constraints, simple structure, no gap, tight sealing, long life, etc.

Under normal system operating voltage, the arrester presents a high resistance state, and only micro-ampere current passes through. Under the action of overvoltage and large current, it presents low resistance, thereby limiting the residual pressure at both ends of the arrester

Classification

There are many types of arresters, including metal oxide arresters, line-type metal oxide arresters, gapless line-type metal oxide arresters, fully insulated composite jacket metal oxide arresters, and removable arresters.

The main types of arresters include tube-type arresters, valve-type arresters, and zinc oxide arresters. The main working principles of each type of arrester are different, but their working essence is the same, all to protect communication cables and communication equipment from damage.

Tube-type lightning arrester

The tube-type lightning arrester is actually a protective gap with high arc extinguishing ability. It consists of two series gaps. One gap is in the atmosphere, called the outer gap. Its task is to isolate the working voltage and prevent the gas-producing pipe from being burned by the power frequency leakage current flowing through the pipe; the other is installed in the gas pipe, called the inner gap or arc extinguishing gap. The arc extinguishing ability of the tube-type lightning arrester is related to the size of the power frequency continuous current. This is a protective gap type lightning arrester, mostly used for lightning protection on power supply lines.

Valve-type lightning arrester

The valve-type lightning arrester consists of a spark gap and a valve plate resistor. The material of the valve plate resistor is special silicon carbide. The valve plate resistor made of silicon carbide can effectively prevent lightning and high voltage and protect the equipment. When there is a high voltage of lightning, the spark gap is broken down, the resistance value of the valve plate resistor decreases, and the lightning current is introduced into the ground, which protects the cable or electrical equipment from the harm of lightning current. Under normal circumstances, the spark gap will not be broken down, and the resistance value of the valve resistor is high, which will not affect the normal communication of the communication line.

Zinc oxide lightning arrester

Zinc oxide lightning arrester is a lightning arrester with superior protection performance, light weight, dirt resistance and stable performance. It mainly uses the good nonlinear volt-ampere characteristics of zinc oxide to make the current flowing through the lightning arrester extremely small (microampere or milliampere level) at normal working voltage; when overvoltage acts, the resistance drops sharply, and the energy of overvoltage is discharged to achieve the effect of protection. The difference between this lightning arrester and the traditional lightning arrester is that it has no discharge gap, and uses the nonlinear characteristics of zinc oxide to play the role of current discharge and disconnection.

The above introduces several lightning arresters. Each lightning arrester has its own advantages and characteristics, and needs to be used in different environments to achieve a good lightning protection effect.

Function

The lightning arrester is connected between the cable and the ground, usually in parallel with the protected equipment. The lightning arrester can effectively protect communication equipment. Once an abnormal voltage occurs, the lightning arrester will act and play a protective role. When the communication cable or equipment is running under normal working voltage, the arrester will not work and it is regarded as a circuit breakers to the ground. Once high voltage appears and endangers the insulation of the protected equipment, the arrester will immediately act to guide the high voltage impact current to the ground, thereby limiting the voltage amplitude and protecting the insulation of the communication cable and equipment. When the overvoltage disappears, the arrester quickly returns to its original state, allowing the communication line to work normally.

Therefore, the main function of the arrester is to clip the intrusion flow wave through the parallel discharge gap or nonlinear resistor, reduce the overvoltage value of the protected equipment, and thus play a role in protecting the communication line and equipment.

The arrester can not only be used to protect the high voltage generated by lightning, but also to protect the operating high voltage.

Seven characteristics:

1. The current carrying capacity of zinc oxide arrester is large

This is mainly reflected in the arrester's ability to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages. The current carrying capacity of the zinc oxide arrester produced by Chuantai fully meets or even exceeds the requirements of national standards. The indicators such as line discharge level, energy absorption capacity, 4/10 nanosecond high current impact tolerance, and 2ms square wave current capacity have reached the domestic leading level.

2. Excellent protection characteristics of zinc oxide lightning arrester

Zinc oxide lightning 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 plate are very good, only a few hundred microamperes of current pass through under normal working voltage, which is convenient to design into a gapless structure, so that it has the characteristics of good protection performance, light weight and small size. When the overvoltage invades, the current flowing through the valve plate increases rapidly, while limiting the amplitude of the overvoltage and releasing the energy of the overvoltage. After that, the zinc oxide valve plate returns to a high resistance state, allowing the power system to work normally.

3. Good sealing performance of zinc oxide lightning arrester

The lightning arrester component adopts a high-quality composite jacket with good aging performance and good airtightness. Measures such as controlling the compression of the sealing ring and adding sealant are adopted. The ceramic jacket is used as a sealing material to ensure reliable sealing and stable performance of the lightning arrester.

4. Mechanical properties of zinc oxide arresters

The following three factors are mainly considered:

⑴ Earthquake force to be borne;

⑵ Maximum wind pressure acting on the arrester

⑶ Maximum allowable tension of the conductor borne by the top of the arrester.

5. Good pollution removal performance of zinc oxide arresters

Gapless zinc oxide arresters have high pollution resistance.

The current national standard specifies the creepage distance level:

⑴ Level II Medium pollution area: creepage distance 20mm/kv

⑵ Level III Heavy pollution area: creepage distance 25mm/kv

⑶ Level IV Extra heavy pollution area: creepage distance 31mm/kv

6. High operational reliability of zinc oxide arresters

The reliability of long-term operation depends on the quality of the product and whether the product selection is reasonable. The following three aspects mainly affect its product quality:

A The rationality of the overall structure of the arrester;

B The volt-ampere characteristics and aging resistance of the zinc oxide valve plate

C The sealing performance of the arrester.

7. Power frequency withstand capability

Due to various reasons in the power system, such as single-phase grounding, long-line capacitance effect, and load shedding, the power frequency voltage may rise or a transient overvoltage with a high amplitude may be generated. The arrester has the ability to withstand a certain power frequency voltage rise within a certain period of time.