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1-1- Passive Arrester
includes a rod tip is simple copper or stainless steel. Franklin's lightning, lightning chuck Jupiter, hedgehog and cable suspended based on the shape and physical properties involves the intensification of phenomena such as the effects of sharp sticks (point effect) and in this way any factor resonator other than the specific form it There, Lightning disabled say. To install these points should be noted:- Put the Lightning on the mast - Use of one or more central conductor - A staple test for every intermediate conductor for measuring earth resistance - Are central conductor of metal objects must be 2 meters - Separate system for each conductor intermediate confidence - The potential wells of the Earth A variety of conventional arresters include: 1. lightning rod 2 arrester with air gaps 3. The arrester tube 4. The long arc arrester (LFA) 5. arrester with nonlinear resistance 6 cables suspended 7. Faraday cage 8. The distribution system grid
The purpose of installing lightning protection systems and people against lightning and make way for the massive flow of lightning into the ground, in such systems rods attract lightning conductors duty descending air flow into the transfer task to the network earthing have. Lightning-making system that is properly designed and installed safety of people and equipment safety will be followed. Instant Lightning divided into two general categories:
1-1-1- Plain shaft Franklin
The first unit was absorbed by Franklin Byshnhad, simple bars that direct lightning strike to the length of the bars, away from the building took place, and the radius of the lightning protection class protective ants simple calculation was based on the theory. Lightning protection class: Protection class is to determine the range in which the probability of a direct lightning strike, is in accordance with a certain percentage. For grades one to four, respectively, 98, 95, 90 and 80% protection considered. Class A is the highest level of protection, the protection is considered to be 98% and respectively 95% and 90% for class 2 and 3 values are calculated. Another point also states that the protection class and the ability to supply it by the thunderbolt.
1-1-3- Arrester tube
The spark arrester includes an air gap for space and another space within a container, which are located together in series. This type of surge arresters in order to shorten the time guided flow (to avoid short circuit) have been prepared. The arrester tube guided during one or more periods after the gas which produces the surge arrester is lost and therefore it can be arrester "spark arrester" is also called. Arrester tube of an insulating tube (R) of synthetic material (PVC, rubber-metal fiber) has been established and within it two solid metal electrode (E) and empty (G), respectively. G electrode or ground wire is connected directly to the tower, but there is a gap between the electrode E and phase grid.R is the tube. Although the internal pressure gas pipes out of the bottom electrode, increases rapidly enough that the hole G ejected at high speeds.a couple of periods, because the carriers of electric charges are not included in the arc does not turn spark off again and remains permanently off and short circuit current is cut off.The tube arresters 10 to 30 kV high-voltage networks are used. The surge arresters are unable to properly guided before cutting limit the scope and capability of guiding cutoff frequency power depends on the short circuit capacity of the system is at fault. The voltage spark arrester The above nonlinear resistance arresters.
1-1-4- LOOP YPE LONG FLASH-OVER ARRESTER(LFA)
Line arresters installed between phase - tower parallel chains insulators or insulator instead of having to pay a heavy price. You should be looking for ways to reduce the cost of installing surge arresters and exit the front lines of discharge voltages of atmospheric discharges was on the line. New ways to protect transmission lines using a long level to guide the electric arc discharge is induced. Between conductor and earth or a long arc arresters can be placed in series with the insulator. The structure of the arrester is very simple and therefore less expensive than other surge arresters. It costs about one-tenth the price is such that ZnO arresters. One of the main advantages of this arrester is no current flow to the grid frequency (PAF) after completion of discharge and transient wave of arc on the insulator. During arresters LFA of the materials that should be protected is higher.
1-1-2- Arrester bar (spark caught with air gaps)
This type of surge arresters or two antennae that are proportional to the voltage on the two electrodes, placed at a certain distance between the conductor and the earth and in the event of voltage, electric arc is established between them. The arch was causing short circuit prevents the voltage, the power supply would also be impaired. In networks with low power, the shape of the antennae, after a relatively short time off the arc and the short circuit current is low, there is no damage due to short circuit. In case of overvoltage, the air gap between the electrodes arc is established and thus the voltage applied to the device is prevented. The main disadvantage arrester bar, the inability to turn off the ignition and when it was struck by lightning spark, the spark will remain until the device is without power. As a result, after every spark, electricity networks and should be re-energized. Overall, the disadvantages of this type of surge arresters the only advantage of the cheaper they are, very high, and includes the following: 1. continue to flow to the ground, even after removing the voltage (resulting in unprotected act and the disruption of the system).2. Short-circuit phase to phase voltage drops in the flow of sparks caught the moment. 3 waves, which can cut winding machines (transformers) threat. 4- affecting the performance of voltage waveforms, as well as environmental conditions (pressure, pollution, humidity, ...). 5. The delay time proportional to voltage (inadequate performance against overvoltages with steep forehead). 6. Distribution of high voltage spark (40%).
1-1-5- Arrester with nonlinear resistance
As we know, the surge arresters should act as a non-linear resistance of the high-impedance voltage network to show and to voltages higher than the rated voltage low impedance network show to be evacuated. The zinc oxide pellets used in Brqgyrv Arstrhay today actually play the role of non-linear resistance that has very little leakage current requirements. Therefore, the voltage divided tablets. So if they can somehow be uniform field. Voltage divider between a more balanced form of tablets to take and rule the life of the tablets is increased and performance is better arresters.
1-1-6- system aerial wire terminal (cable suspended)
Notation: one or more air conductor wire - two towers to harness wire - separate system for each conductor middle ground - the potential for ground systems
1-1-7- Faraday cage
With the expansion of buildings and the limitations of simple rods, Faraday cage (Faraday Cage) Franklin was simple alternative bars, today most international standards using the best method known Faraday cage. This method is tried building was enclosed in a cage of steel or copper conductors.
1-1-8- Mesh Terminal System
The system includes several Struts and attached to each other that all the bars are connected by wires connected to the ground. Tips for several Struts - a rod connected to the network - for every band needs a middle conductor - a conductor between the need for a separate card is well - the potential for ground systems.
1-2- Lightning active
Lightning that by receiving energy from an external source or self-generated, the effects of phenomena such as or Corona Effect amplified the point effect, have a wide variety. They kind of nuclear power - wind (piezoelectric) - Solar - electric - capacitive and named.Dependent or self-sufficient: the need for energy, active lightning can be divided into two groups. To activate an external source such as a battery or those in power are in need and those who can not work without energy by an internal mechanism of the surroundings receive. The first type is called self-dependent and Type II.
1-2-1- Types of self Lightning
- Lightning nuclear - Lightning pneumatic or piezoelectric- Solar lightning - Lightning capacitive electronic meters - atmospheric Lightning meters of self-listed (atomic lightning, lightning, wind, solar lightning) each has disadvantages which have limited their use. Which already use electronic meters capacitive lightning - atmospheric due to the use of technology are among the most used Instant lightning. The following is briefly discussed.
1-2-2- Lightning capacitive electronic meters - atmospheric
The lightning voltage sensing unit when the atmosphere beyond a certain limit (eg 5 kV m) can be used to collect energy charging unit throws. The unit continues to fill capacitors used in an electronic circuit. The unit when the potential of the atmosphere a certain amount (close to the lightning, for example, about 100 kilo volts per meter) pass, the charging of the capacitor to the evacuation center electrode connected to the ground. This will cause the ionization of the air around the lightning. This sequence is repeated with increasing intensity of the atmospheric potential. The mode of action of this type of lightning absolute dependence on weather conditions, lightning-prone due to its best performance. The system just before the occurrence of lightning electric-containing atmosphere suddenly increased, and that switching the ignition sensing and control unit.ionize them. How ionization at the tip of the lightning: Ion controlled release unit of the igniter (TRIGGERING) conditions are created to provide Faithful of ions around the rod tip. The unit should be carefully controlled release of ions that just a few microseconds before the lightning discharge will be. The presence of large volumes of electric charges around lightning and sudden increase in the electric field before lightning environment, makes the time of the corona (corona effect triggering) is very short. . The original name of this lightning of ESE (Early Streamer Emission) is. Last basis of these strikes end, which produces ionized ball around lightning, lightning currents may have hit the local area and the ball hit the skin. T Baδ time that is known to activate or Advanced Time from when the lightning is faster than a conventional surge arrester operates. Since the upward flow rate of about a microsecond in meters. Therefore, another parameter called ΔL is one that is the subject of ionized sphere radius. V = (ΔL) / ΔT = 1m/μs → if (ΔT = 30 μs) → ΔL = 30 m Based on the above, the thunder of the active time of 30 microseconds, with a 30 meter radius sphere is ionized capacities.
1-3- Important factors in the damaged surge arresters
Many factors have contributed to the injury actually arrester and can affect performance and even cause them to burst arrester. Arrester injury factors include: 1. moisture and pollution2. transitory voltages 3. Inappropriate use of surge arresters 4. Non-compliance with operating conditions characteristic arrester (bad design)
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