Zinc oxide arrester features _ zinc oxide arrester working principle _ zinc oxide arrester model meaning

Zinc oxide arrester is a new type of arrester developed in the 1970s. It is mainly composed of zinc oxide varistor. Each piece of varistor has its own switching voltage (called varistor voltage) when it is made. Under normal operating voltage (ie less than varistor voltage), the varistor value is large, equivalent to the insulation state, but in Under the impact voltage (greater than the varistor voltage), the varistor is broken down at a low value, which is equivalent to a short circuit condition. However, after the varistor is struck, it is possible to restore the insulation state; when the voltage higher than the varistor voltage is cancelled, it returns to the high resistance state. Therefore, if a zinc oxide surge arrester is installed on the power line, when a lightning strike occurs, the high voltage of the lightning wave causes the varistor to break down, and the lightning current flows into the earth through the varistor, so that the voltage on the power line can be controlled within a safe range. This protects the safety of electrical equipment.

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

The zinc oxide surge 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 non-linear volt-ampere characteristics of the zinc oxide valve plate are excellent, only a few hundred microamps of current is passed through the normal operating voltage, which is convenient to design a gapless structure, which has good protection performance, light weight and small size. feature. When the overvoltage invades, the current flowing through the valve plate increases rapidly, and the amplitude of the overvoltage is limited, and the energy of the overvoltage is released. Thereafter, the zinc oxide valve plate returns to a high resistance state, so that the power system works normally.

3. Sealing performance

The arrester component adopts a high-quality composite jacket with good aging performance and good air tightness. It adopts measures such as controlling the compression of the sealing ring and adding sealant. The ceramic jacket is used as a sealing material to ensure reliable sealing and stable performance of the arrester.

4. Mechanical properties

The following three factors are mainly considered: the seismic force to withstand; the maximum wind pressure acting on the arrester; the maximum allowable tensile force of the wire at the top of the arrester.

5. Decontamination performance

The gapless zinc oxide arrester has high stain resistance.

The creepage ratio specified by the national standard is: Class II medium pollution area: creepage ratio 20mm/kv; Class III heavy pollution area: creepage ratio 25mm/kv; Grade IV heavy pollution area: creepage ratio 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 the products affecting it mainly has 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; and the sealing performance of the arrester.

7. Power frequency tolerance

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

The current through the zinc oxide arrester valve at rated voltage is only small, equivalent to an insulator. When the voltage on the metal zinc oxide surge arrester exceeds a fixed value, the valve plate "conducts" to discharge a large current through the valve plate into the ground, and the residual pressure does not exceed the withstand voltage of the protected device. When the applied voltage drops below the operating voltage, the valve automatically terminates the "on" state and restores the insulated state.

(1) Rated voltage refers to the maximum effective value of the power frequency voltage allowed between the two ends of the arrester during normal operation. That is, when the system short-time power frequency over-voltage is directly applied to the ZnO valve, the arrester is still allowed to absorb the specified lightning and Operating overvoltage energy. The characteristics are basically unchanged and no thermal breakdown will occur.

(2) The maximum continuous operating voltage allows the maximum value of the maximum power frequency voltage to be continuously applied between the ends of the arrester. Its value is generally equal to or greater than the maximum operating phase voltage of the system. This voltage determines the aging performance of the arrester for long-term operation.

(3) The reference voltage includes a power frequency reference voltage and a DC reference voltage. It refers to the power frequency voltage peak or DC voltage of the lightning arrester passing through the peak of the lmA power frequency current resistive component or 1nRJL DC current.

(4) Residual pressure is the residual voltage across the arrester when the arrester operates, that is, the voltage peak between the terminals when the discharge current flows through the arrester.

(5) The pressure ratio is the ratio of the residual voltage when the arrester passes a large current to the voltage when the DC current is passed through the ImA. The smaller the pressure ratio, the lower the residual voltage at high currents, and the better the protection performance of the zno arrester. Currently, this value is about 1.6~2.0

The function of the zinc oxide zgxhg.com lightning rod is essentially a lightning-leading effect, which can generate an additional electric field to the lightning electric field. This additional electric field is caused by the thundercloud generating electrostatic induction to the lightning rod, which distorts the lightning electric field and thus thundercloud. The discharge path is attracted to the lightning rod itself in the direction that may be developed to the protected object, and then the lightning current is discharged into the earth through the down conductor and the grounding device connected with the lightning rod, so that the protected object is protected from direct lightning strike. Therefore, the lightning rod is essentially a lightning rod, which introduces lightning current into the ground, thereby protecting the line, equipment and buildings.

Each type of arrester has its own advantages and characteristics, and needs to be used in different environments to achieve good insulation. The arrester is equivalent to an insulator at rated voltage and will not cause any action. In the event of a crisis or high voltage, the arrester will act to introduce current into the earth and effectively protect the power equipment.

H - composite coat

Y——Zinc oxide arrester

5——Nominal discharge current (KA)

W - no gap

Z——power station type; X——line type; S——distribution type; D——motor type;

R——capacitor type; L——explosion proof type

90——-rated voltage (KV)

220——Residual pressure (KV) under nominal inrush current

E.g:

For example, the model HY5WR-17/46 indicates that the rated voltage of the zinc oxide surge arrester is 17KV, the maximum residual voltage is 46KV, and the nominal discharge current is 5KA.

(1) Install on the chimney. According to the different heights of the chimney, generally 1 to 3 lightning rods are installed. It is required to add the disconnecting clips at the position of the lowering line 1-8m from the ground and protect them with angle steel. The lightning rods should be hot-dip galvanized.

(2) Install on the building. The installation of lightning rods on the roof and side walls shall be carried out in accordance with the relevant standards. The lightning rod should be made to include the entire weight of the bottom plate, the support plate, the bolts, and the like. The lightning rod is produced by the construction unit according to the drawings.

(3) Installation on a metal container. The installation of the lightning rod on the top of the metal container and on the tank wall shall be carried out in accordance with the relevant standards. (4) Independent lightning rod installation. Independent lightning rods are equipped with two types of independent lightning rods and independent lightning rods for reinforced concrete ring rods.

1 Reinforced concrete ring independent lightning rods are divided into three types: no lighting, single lighting, double lighting, etc. The total height is divided into 11m, 13m, 15m, 17m, 19m, etc. from the ground to the tip. Do not stir the surrounding soil when excavating the foundation pit and prevent rainwater from penetrating.

2 When the soil around the foundation cannot be guaranteed, the backfill must be layered and compacted. At this time, the template should be applied when pouring the foundation. After the ring rod is hoisted, it is fixed with a drawstring. When the strength of the cast-in-place concrete of the foundation pit reaches 70% or more, the drawstring can be removed. After the needle tube is assembled, the surface should be galvanized, and the remaining iron parts should be painted with red lacquer and gray paint twice.

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