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Network with long-term measurement of earth resistance

Length D,[link widoczny dla zalogowanych], ground network center to the edge of the count by 0.5D, then the current polar distance to network edge should be 4.5D, 2D potential is at most (see Figure 2). Loop 2 is not enough open space the actual measurement, the current is so great and sometimes not reach the required distance. Therefore, the recommendation has documented the other two methods: 0.618 Compensation Act and the isosceles triangle Tong law. Both of these certificates by the number theory, theory of error in the l% below the actual error is less than l0%, away from the current electrode and the grounding network than just 2D. Considering the majority of aviation ground equipment, ground network within the diagonal in the 75m, it is recommended to prepare l50m, 114.6m and 35.4m three wires, torsion in the reel, the measurements in different ways to connect two wires. If elected to the Oval for the drainage network center point, the compensation method can be implemented 0.618. Set away from the current electrode to network center l50m +35.4 m is equal to 185.4m Department, potential polar distance to network center 114.6m and set in the same direction with the current electrode. 114.6 precisely l85.4 of 0.618 times (see Figure 3). Buildings such as the measurement of the external lightning protection grounding resistance, earth lead wire network center is not only to the network edge as the drainage point, isosceles triangle method can be used, the potential pole with l50m line, current electrode which can be accessed l14; 6rn line +35.4 m lines, power pole and the potential of a very hidden away from 75m, the angle between two connecting wire 2,[link widoczny dla zalogowanych], wire and the angle between the edge of the network are equal (see Figure 4). Edge of drainage network from the ground can also 0.618 Compensation Act. Figure 5 shows the 0.618 cabling commonly used engineering method, the potential of the center pole from the ground network 1.5D = 60 (2.5D), 2.5D is the current electrode distance from the center to the ground network. 60 is approximately equal to 0.618. Measurement Technology 1998. N912, - an I14 from the mouth of a 70Bln ----- ---- 7 to 15 ring 354 ------ Figure 3 from the three current electrode set to apply for the 2D method of relatively uniform soil resistivity {If alluvial plains in the soil resistivity is uneven, the direction of East and West the apparent inconsistency of resistance testing hills and mountains, according to the State Water Resources Ministry of SD standard \with 3D. To eliminate the impact of uneven soil resistivity, using far more effective method, that is to play away from the current electrode to 5D at the network center, shown in Figure 2. As long traverse, in order to overcome the current line to line voltage induced interference,[link widoczny dla zalogowanych], very best to potential and current were set at the grounding pole on both sides (see Figure 6). By grounding the left side of zero potential at infinity, such as the potential to set the distance is extremely 5D, measurements will be 85% of the actual value. jL-f I - Circle 6 meter ground resistance as small power supply, the resulting measurement current is also small, less than 50mA, the measurement vulnerable to strong radio interference, interference with the greater the longer route. High-frequency interference will cause the meter pointer jitter or LCD digital jump of 0.1 in the parallel capacitor voltage loop solution. Large substation in the power sector net a few hundred meters long diagonal, traverse Deshu km long,[link widoczny dla zalogowanych], usually current voltage meter. To make into the ground current is large enough, the general control of the range of 2O ~ 100A, the use of 220 ~ 380V for power utility to do measurements. Measurement process is relatively complex,[link widoczny dla zalogowanych], will encounter a strong frequency interference. Drainage point of contact resistance in order to avoid the impact of the four terminals that should be used as four terminal's ground resistance tester, regardless of whether the measured resistance is less than 1D, E should remove the two poles (or C, P pole) of the short films. Cancel battery spring clip, with two c instead of with the grounding clip attached to the clip is usually connected in the current loop, voltage loop clip in the next, as shown in Figure 3. Good contact with the probe so that wires can be in the top dozen 4ram probe hole, install the terminal, four measurement wires welded at both ends of technetium-ray film can be. Ground measurements are not trivial, involving work equipment and ergonomic safety. Around the new airport construction, ground measurements frequently eager to regulate the operation of ground measurements. In short, measuring earth resistance in addition to the basic principles of clear, must take into account the network covers an area of ground, ground network of superficial and deep areas where the soil conditions and various disturbances and many other issues, but also self-measurement accessories. Grounding resistance measurement method is not perfect so far, these issues should be taken seriously. ● test [1] Tseng forest. Grounding techniques. Beijing Water Conservancy and Electric Power Press, 1979 [2] possession of plum trees. Small hydropower. Beijing Huan Electric Water Power of a Press, 1992 [3] Yun-Ci Dong Guang solution. Power system grounding. Beijing Water Conservancy and Electric Power Press. 1996 left a lying

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