Lightning Arrester Principle 33702p

LIGHTNING ARRESTOR, LIGHTNING ROD, LIGHTNING CONDUCTOR, LIGHTNING ARRESTER

Specification and Parameters Item DK6-100 Type Current Limiting Lightning Arrestor Discharge Capacity 300kA (10/350µs) Amplitude Damping Radio ≥82% Gradient Damping Multiplying Radio ≥35 Current Limiting Impedance Value ≤2Ω Weight (Kg) 45 Height (m) 2.1 Installation Size (mm) Φ175±0.5 Zinc Coated Tower/pole (each piece, mm) Φ114X3000(H)X4(Screw) Art No. 100101001 Requirements of Installation and Detection Height of Installation At least 1.5m higher than the protected object Earthing Resistance ≤30Ω Earthing Downlead One piece or multi pieces of Steel Bar (Steel Flat) which Diameter (or equal sectional area) shall be no less than 8mm Wind Load No less than 45m/s Applicable Scope This product is widely used for preventing lightning direct stoke to the following area: Telecom, Petroleum, Chemical, Electric Power, Meteorology, Microwave Communication, Broadcasting, Oil Tank Farm, Electric Transformer Substation, Aviation, Financial System, Network, Industry and Highrise Building Usage 1. Conduct the direct lightning stroke 2. Leader Stroke in advance, conduct the electrical currents to ground, no phenomenon of shielding failure nor side stroke 3. Low grounding electrical currents, decrease the occurrence rate of counter strike which caused by potential difference that caused by enormous electrical currents flow to ground. Weaken the phenomenon of induced over-voltage caused by the enormous electrical currents presenting to the grounding weir.

Spherical lightning rod It is applicable for the building, depot, pumping station, satellite communications devices, airport, and so on.

Lightning arrester or surge arrester(6kv station type) 6kV station type lightning arrester or surge arresterLight weight , install on the existing lines Series gaps discharge steadily and can prevent effectively the deterioration of resistor Without gaps with the disconnector is a kind of free maintenance electric equipment Oxide zinc arrester that has the good performance of sealing, polymer insulation housed has the strong anti-pollution, so the product is the ideal transmission anti-lightning protecting device

Lightning arrester Category: How things work

This instrument really has saved millions of lives on earth. Introduction: The lightning arrester (or) the lightning conductor is a commonly used device which is used to save tall buildings and towers from the attack of lightning. Principle: The basic principle behind this life saving system is the "action of points" (or) "corona discharge". It is nothing but the discharge (or) leakage of electric charges from the sharp points of a charged conductor. Construction: The apparatus consists of a long thick rod made up of copper which is a very good conductor of electricity so that it can allow a large amount of charges to flow through it. This copper rod es through the walls of the building. The upper end of the rod is provided with a metal plate having a number of sharp spikes which are visible at the top of the building while the lower end is connected to a plate of copper which is deeply buried in the ground so that the excess of charges is ed to the earth which is a good conductor of electricity and this process is called "earthing". Function: The working of a lightning arrestor can be explained either with a positively charged cloud commonly called "male cloud" or with a negatively charged cloud commonly called "female cloud". Consider a negatively charged cloud which es over the building with a lightning arrestor. Due to the negative charge of the cloud, positive charges are induced to the sharp spikes which are at the top of the building. Now, due to the principle of action of points, leakage of the positive charges from the sharp spikes occurs so that the nearby atoms in the space are ionized into positive and negative charges. Now, the positive charges in the sharp spikes repel the newly formed positive ions and these ions try to neutralize the negative charge of the cloud. If the negative charges are not completely neutralized, these charges due to the attraction of the positive charges in the sharp spikes are ed through the copper rod to the ground where they are earthed. Thus, the intensity of lightning can be reduced thus saving the building from its destructive attack. A lightning conductor can save its surroundings for more than half a kilometer from the attack of lightning. Usage: Today, the lightning conductor is used almost in all tall buildings, towers and other tall spots. Hence, it is really a life saving system. http://www.indiastudychannel.com/resources/114976-Lightning-arrester.aspx

LIGHTNING ARRESTERS The earthing screen and ground wires can well protect the electrical system against direct lightning strokes but they fail to provide protection against travelling waves, which may reach the terminal apparatus. The lightning arresters or surge diverters provide protection against such surges. A lightning arrester or a surge diverter is a protective device, which conducts the high voltage surges on the power system to the ground

Fig 7(i) shows the basic form of a surge diverter. It consists of a spark gap in series with a non-linear resistor. One end of the diverter is connected to the terminal of the equipment to be protected and the other end is effectively grounded. The length of the gap is so set that normal voltage is not enough to cause an arc but a dangerously high voltage will break down the air insulation and form an arc. The property of the non-linear resistance is that its resistance increases as the voltage (or current) increases and vice-versa. This is clear from the volt/amp characteristic of the resistor shown in Fig 7 (ii). The action of the lightning arrester or surge diverter is as under: (i) Under normal operation, the lightning arrester is off the line i.e. it conducts no current to earth or the gap is nonconducting (ii) On the occurrence of over voltage, the air insulation across the gap breaks down and an arc is formed providing a low resistance path for the surge to the ground. In this way, the excess charge on the line due to the surge is harmlessly conducted through the arrester to the ground instead of being sent back over the line. (iii) It is worthwhile to mention the function of non-linear resistor in the operation of arrester. As the gap sparks over due to over voltage, the arc would be a short-circuit on the power system and may cause power-follow current in the arrester. Since the characteristic of the resistor is to offer low resistance to high voltage (or current), it gives the effect of short-circuit. After the surge is over, the resistor offers high resistance to make the gap non-conducting.

TYPES OF LIGHTNING ARRESTERS There are several types of lightning arresters in general use. They differ only in constructional details but operate on the same principle viz, providing low resistance path for the surges to the round. Following are the different types of lightning relays: 1. Rod arrester 2.Horn gap arrester 3. Multigap arrester 4. Expulsion type lightning arrester 5. Valve type lightning arrester

ROD GAP ARRESTER It is a very simple type of diverter and consists of two 1.5 cm rods, which are bent at right angles with a gap in between as shown in Fig 8. One rod is connected to the line circuit and the other rod is connected to earth. The distance between gap and insulator (i.e. distance P) must not be less than one third of the gap length so that the arc may not reach the insulator and damage it. Generally, the gap length is so adjusted that breakdown should occur at 80% of spark-voltage in order to avoid cascading of very steep wave fronts across the insulators. The string of insulators for an overhead line on the bushing of transformer has frequently a rod gap across it. Fig 8 shows the rod gap across the bushing of a transformer. Under normal operating conditions, the gap remains nonconducting. On the occurrence of a high voltage surge on the line, the gap sparks over and the surge current is conducted to earth. In this way excess charge on the line due to the surge is harmlessly conducted to earth Limitations: (i) After the surge is over, the arc n the gap is maintained by the normal supply voltage, leading to short-circuit on the system. (ii) The rods may melt or get damaged due to excessive heat produced by the arc. (iii) The climatic conditions (e.g. rain, humidity, temperature etc.) affect the performance of rod gap arrester. (iv) The polarity of the f the surge also affects the performance of this arrester. Due to the above limitations, the rod gap arrester is only used as a back-up protection in case of main arresters.

    

VALVE TYPE ARRESTER EXPULSION TYPE ARRESTER MULTIGAP ARRESTER HORN GAP ARRESTER ROD GAP ARRESTER