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Hardware Web: www.JS Hardware.com JS HARDWARE CHINA www.js hardware.com Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;Hardware fittings installation river crossing The test of spacer damper Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;The inspection for Vibration damper 2. Insulator String and Fittings .1 Principle for Selection .1.1 Basic Requirements Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Spacer should be with good mechanical performance to ensure reliable mechanical strength with reasonable weight, goods damping performance and ability to endure long time fatigue vibration. The corona free design of the line should satisfy the needs of ensuring insulator working normally under ±800kV voltage, radio interference created should be in conformity with the regulations and requirements specified in GB/T2317.2 2000 Electrical Fittings “Corona and Radio Interference T ests”. It must be ensured that no corona will be discharge during the normal working of fittings. Maximum working load Line broken Joint Broken Normal Load Disk Insulator 2.7 1.8 1.5 4.0 Fittings 2.5 1.5 1.5 Wind Velocity m/s 10m (base) Gale 31.8 35.4 37.7 41.3 Over Voltage 15.9 16.5 17.7 18.8 20.6 Gale 33.4 34.7 37.1 39.6 43.3 Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;2.1.4 Standard Value of Wind Load Wind pressure uneven coefficient, wind load adjustment of conductor and earth wire, coefficient Base Wind Velocity V(m/s) V31.5 31.5 Calculate Tower Load 0.75 0.70 at 1.0 Wind load increasing coefficient of conductor, earth wire and tower shall be considered when Thickness of Covering Ice mm Wind Load Increasing Coefficient of Conductor, Earth wire and Insulator in ice covering condition 1.2 1.3 1.5 20 1.5 .2 Mechanical Load Conductor used for the Ice area under 20 mm shall adopt 6×ACSR 720/50, while those under 30 mm is temporarily defined to be 6×AACSR 720/50 steel core aluminum alloy stranded lines. The wind velocity is defined according to the conditions as 10 m high above ground, once 100 years, average 10 minutes' maximum wind velocity which is also the base design base wind velocity is at 27m/s, 28m/s, 30m/s, 32m/s and 35m/s.The designed covering ice includes 10 mm light ice, 15 mm medium ice, 20 mm heavy ice and 30 mm h eavy ice etc. Based on tower plan conclusion, the total load of each type of tower is as following: Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Table Light Ice Area Conductor Insulator String (V String) Load Tower Type Shifting Angle Coefficient V Type String Angle (°) Comprehensive Load (kN) Single Leg Load (kN) Tonnage Single Leg Joints Number K=2.7 K=3 K=2.7 K=3 Section I 27/28/30 m/s b 10mm H1000m Z27101 0.8 400kN Z27102 0.75 400(240)kN 1(2) Z27103 0.7 240(300)kN Z27104 0.65 300(400)kN Z27105 0.7 400kN Z27106 0.7 1002 1114 300kN ZK2710 0.6 300kN ZJ27101 (3° 12°) 0.7 60/30 300kN ZJ27102 0.7 63/30 400kN Section II 32m/s b=10mm H500m ZV3210 0.8 400kN ZV3210 0.75 400kN ZV3210 0.7 240kN ZV3210 0.65 300kN ZV3210 0.65 400kN ZVF3210 0.8 400kN ZVF3210 0.75 400kN ZVF3210 0.7 240kN Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;ZVK3210 (ZVK3210 1P) 0.9 511 300kN ZVK3210 (ZVK3210 2P) 0.9 240(300)kN ZVK3210 (ZVK3210 3P) 0.9 411 240kN ZVJ3210 0.75 60/40 300kN ZVJ3210 12° 0.75 60/30 400kN Section III 35m/s b 10mm H500m ZV3510 0.85 400kN ZV3510 0.8 400(240)kN ZV3510 0.75 240(300)kN ZV3510 0.7 115 300(400)kN ZVK3510 0.9 300kN ZVK3510 0.9 240kN ZVJ3510 0.75 60/45 300(400)kN ZVJ3510 0.75 60/30 400kN Section IV 27/28 m/s b 15mm H1000m Z27151 0.75 411 240kN Z27152 0.7 240(300)kN Z27153 0.65 300(400)kN Z27154 0.7 400kN Z27155 0.7 1035 400(300)kN 2(3) Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Z27156 0.7 1150 1278 1031 400kN ZK2715 0.8 400kN ZJ2715 0.75 60/35 300(400)kN Section V 30m/s b 15mm H1000m Z30151 0.75 240kN Z30152 0.70 300kN Z301531 0.65 400kN Z301532 0.7 400kN Z30154 0.7 400(300)kN 2(3) Z30155 0.7 1035 300(400)kN Z30156 0.7 1150 1278 1071 1190 400kN ZK3015 0.8 400kN ZJ3015 0.75 60/40 400kN Note: 5% increasing of suspension point tension has been considered for tension string load. Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Table 5 Allowed Vertical Span for Suspension V String in Heavy Ice Area (m) Number of Strings x Strength Allowed Vertical Span for Suspension String Remark 2×300kN 2×400kN 2×550kN 4×210kN 4×300kN 4×400kN 4×550kN String Weight (kg) 3180 3380 3780 5050 6600 7200 8000 20mm 1420 LH=300 1325 LH=500 30mm LH=300 110 LH=500 Note: a. 20 mm ice area adopt conductor of 6×ACSR 720/50 and 30 mm ice area adopt conductor of 6×AACSR 720/50 steel core aluminum alloy stranded lines. b. Effect of string weight has been considered for the vertical load calculation. c. Control working condition is ice covering condition. d. Typical span is 350 m. Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;2.3 Insulator String Assembly Type in Light Ice Area Subject to the conclusion of Book IV Volume VI of Study on the Insulator Coordination and Insulator Type Selection, the insulator can be ceramic, g lass, composite or post insulator, while disk insulator or composite insulator can be used as suspension insulator in light polluted area, which should be selected according to the weather conditions, working experience and insulator string configuration a long the line. Suspension insulators in medium polluted area and severely polluted area are using composite insulators. Disk insulators are applied as tension insulators. .3.1 Conductor Suspension String 1) String Type Selection Normally there are I s tring and V string for conductor suspension string, V string can reduce conductor spacing and further reduce the tower single base weight, decrease corridor width, lessen house demolition, reduce trees felling and Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;on the pressure test research of V type insulator string of 500kV line. According to the research results of V type insulator string voltage tests by Southwest Electric Power Design Insti tute and Wuhan High Voltage Research Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;2×210kN, 2×300kN, 2×400kN, 2×530kN types of strings are recommen ded to be used for conductor V type suspension insulator strings in light ice area of this engineering. Each leg 2×240kN , 2×300kN, 2×400kN, 2×550kN types of strings are recommended to be used for V type composite insulator strings. Refer to the following for single joint and double joints V string arrangements in light ice area: Figure 1 Schematic Diagram for Single Joint and Double Joints V String in Light Ice Area 4) L Type String L type string is used in small tangent angle tower, as per calculation, 2×300kN and 2×400kN combination should be adopted for L type string, the angle of which are 60°+30°, 60°+35°, 60°+40° and 60°+45° respectively, with double hanging points, refer to the following for L type string arrangements: Figure 2 Schematic Diagram of L Type String Arrangement in Light Ice Area Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;2.3.2 Conductor Tension String 1) Tension String Type The maximum load of tension string in 10 mm ice area is 372.96 kN, tension string insulator strength is required to be 1007kN. While that in 15 mm ice area is 408.52 kN, and a tension string insulator strength of 1103 kN is required. Tension string can be the types as 2×550kN 10mm ice area , 3×400kN or 4×300kN, Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;experiences in the domestic 500kV and large spanning line; 4×300kN horizontal tension string is with the most complicated structure, the most insulator number, higher insulator failure rate and largest maintenance workload. Number of Insulators Cost for Each base Tower (10 thousand yuan) 37.63 36.10 39.44 From the above we can see: triple joints 400kN insulator is with competitive price, the issue to be cleared is the influences on the weight of the tower of the three types insulator strings. According to previous experiences, quadruple joints 300kN, triple joints 400kN and double joints 550kN insulator string types are with little influence to the tower weight, price will be the dominant factor, assuming 515 bases for the whole line tension towers, when calculating at a minimum price difference of RMB 15.3 thousand, there will be a saving of RMB 7.88 million for the whole line when using triple joints 400kN type, this is a considerable amount for this engineering, the triple joints 400kN insulator string is with obviously lowest price, quadruple joints 300kN is with a higher price and double joints 550kN, the highest. Above all, the least joints 3×400kN tension string in light ice area is suggested to be the first choice, and 3×400kN, the second choice, 2×550kN (light ice area), the third choice. Refer to the following for the assembly of the first recommendation 3x400kN tension string: Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;Figure 4 Schematic Diagram of Light Ice Conductor 3×400kN Tension String .3.3 Joints Spacing Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;independently, the pollution flashover voltage of dual joints parallel strings is 3.9% Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;multiple joints insulator strings in this engineering. Table 7 Rec ommended Values of the Conductor Joints Spacing Ice Area Suspension String Tension String Light Ice Area 650mm 650mm .4 Insulator String Assembly Type in Heavy Ice Area According to the conclusion in Technical Research of Heavy Ice Area Line Design, disk insulator should be used in heavy ice area. .4.1 Conductor Suspension String As per calculation, tower weight can be decreased when V string is used in heavy ice area, meanwhile the using of V string restricts the wind shifting of the insulator string, reduces the corridor width. Therefore V string is recommended to be used as conductor insulator string in heavy ice area. The maximum shifting angle of windward leg insulator string should be controlled within 7 , V string angle should be designed according to the following: Table 8 Heavy Ice Area V String Angle (20 mm and 30 mm ice, 30m/s wind) Tower Type Kv Coefficient Wind Shifting Angle V String Angle ZV21 0.85 ZV22 0.65 49.7 ZV23 0.75 ZV31 0.85 ZV32 0.65 49.7 ZV33 0.75 According to the conductor selection and separation number in heavy ice area, and based on mechanical load calculation, the conductor suspension V string configuration in heavy ice area of this engineering is as following: The combination of each leg sin gle joint 400kN and 550kN insulator strings and double joints 210kN, 300kN and 400kN insulator strings can be used for 20 mm ice area conductor suspension V string. Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;The combination of each leg double joints 210kN, 300kN and 400kN insulator strings can be used for 30mm ice area conductor suspension V string. In order to avoid the uneven ice covering and the uneven force of double joints insulators or the collision of them when in off ice jumping, it is recommended to use single hanging point for double j oints V type string in heavy ice area. Refer to Figure 7 5 for double joint V type strings arrangement in heavy ice area. Figure 7 5 Schematic Diagram for Heavy Icy Area Double Joints V String .4.2 Conductor Tension String 1) The maximum load of each pole conductor tension string in 20 mm ice area is 436.3kN, therefore 3×400kN and 4×300kN types can be used as tension strings. The maximum load of each pole conductor tension string in 30 mm ice area is 59 2.42kN, the insulator strength of the tension string is required to be 1599.5kN, therefore 3×550kN and 4×400kN types can be used as the tension strings. Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Quadruple strings are with the shortcomings of complicated structure, more insulators and fittings, h igher insulator failure rate during working, large maintenance workload, difficult to adjust when the two independently connected strings are with different lengths and easy to cause the long term uneven force of the insulator strings. While the triple joi nts structure is in a simpler structure, with Figure 7 6 Schematic Diagram for 30mm Ice Area Tension String Arrangement .4.3 Joints Spacing Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;Off ice jumping is supposed to be happening to the insulator string in heavy ice area, which shall become more serious following the increasing of the thickness of the covering ice. After the conductor off ice jumping, the insulator string will be shaking severely, as there is too long a string length, the shaking of the string is more severe than that of 500kV line, if the joints spacing is too small, collision of Ice Area Suspension String Tension String Heavy Ice Area 800mm 1000mm 2.5 Jumper wire pattern Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;breaking point and corona can occur easily, e specially in coupling area of aluminum tube and terminal, and with higher cost of manufacturing than cage type jumper. Therefore, cage type rigid jumper is recommended for strain tower. At present there are two patterns of cage rigid jumpers of V String a String. it will add an additional cost of RMB 6,580,000 by adopt V String cage rigid jumper than I string cage rigid jumper for the whole line. However, the property to avoid wind deflection of V string cage rigid jumper and its electric reliability i Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 1 ;&#x/MCI; 1 ;&#x/MCI; 2 ;&#x/MCI; 2 ; &#x/MCI; 3 ;&#x/MCI; 3 ;Figure 7 Diagram of arrangement of cage rigid jumper .6 Earth wire fittings As being computed for mechanic property and tested for overload capacity on heavy icing area, 20mm of the earth wire and off ice area shall adopt LBGJ 180 20AC aluminum clad steel standed conductor and 30mm ice area shall adopt G 210 galvanized steel stranded wire. Suspension fitting string of earth wire and strain fitting string should directly connected to the ground. .8 Main selection of fittings Fittings mainly include tower connecting fittings, suspension clamps, six yoke plates, spacer dampers, and grading rings. Fittings are the important parts connected to circuit for safe operation. If fittings become ineffective and damaged, circuit will be damaged and interruption of power supply will be caused. Therefore, fitt ings shall be of high reliability. They shall meet current related standards and other special requirements in this project. In addition, the conveniences to transport, install, repair, and replace fittings shall be taken seriously. Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;2.8.1 hardware fittings connected to towers GD Clevises and GD trunnion clevises are the main two kind of fittings connected Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;According to design and operation experience of extra voltage transmission line and in consideration to factors like abrasion, the strength grade of fittings for connecting tow ers is generally higher than that of other connection fittings, i.e. matching the grade of insulator strength. According to the distribution condition of suspension string and patterns of strain string, there are six strength grades of fittings for connect ing towers, are 320kN, 420kN, 530kN, 640kN, 840kN, and 1060kN. Whole forging workmanship shall be used to process fittings for connecting towers. 2.8.2 Six bundle suspension yoke plate The key hardware fittings in suspension string is the type selection of six bundle suspension yoke plate, which adopts combination yoke plate and integral yoke plate in 750kV AC transmission line.The six bundle suspension yoke plate of 500kV compact line in China all adopt integral type, which have the advantage of stability, few er hardware fittings, simply structure, but heavier for single part. It is easy to transport in mountainous area from the experience of design and construction. Therefore, the integral six bundle suspension yoke plate is recommended in this project. Six ndle suspension integral yoke plate is as the following drawing: Drawing 7 Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;It may adopt 420kN 640kN 840kN 1280kN 1680kN (In heavy icing areas) because the strength of suspension yoke plate is same as t he strength of insulator string. 2.8.3 Six bundle tension yoke plate The six bundle tension yoke plate also has two types: integral and combination type . The integral type is good in stability, fewer hardware fittings, simply structure. The single piece of com bination yoke plate is easy to fabricated, transport and installation of its light weight. It recommends combination yoke plate to the project area with 20mm and below, due to integral yoke plate is weight 200kg for a single part, it is inconvenient for tr ansport and installation. While for the area of 30mm icing areas, it is recommended to use integral type because of good stability of integral type. The following drawing is the recommended six bundle tension string combination yoke plate and integral yoke plate when tension string adopts 3×400kN insulator string. Drawing 7 Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;2.8.4 Suspension clamp The corona issue of hardware fittings shall become a major problem by the increasing of voltage in HVDC line. There are two anti coro Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;swinging up and down of suspensi on clamp is small, because of the stressed shaft of trunnion type suspension clamp is on the axle wire of conductor, that’s to say the caused stress by the swinging up and down of suspension clamp is small to conductor, and will minimize the fatigue damage of conductor to the most, Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;4) There should be enough contacting surface between the suspension clamps and the installed conductors, and the damages caused by faul t current will minimize. 5) The grip strength of the suspension clamps should no less than 24% of the calculated tensile strength of the conductors; According to the situations of the suspension string applied to this project, the strength of suspension clamps will classified to four grades, 100kN, 160kN, 210kN and 300kN (for the heavy ice zones). it is usually install the preformed armor rods at the condition of large vertical span, The trunnion type suspension clamp The envelop type suspension clamp Fig. 7 11 The suspension clamp types For ±800kV EHV DC transmission line projects, it is required to used products Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;with good performance; and also have the requirement on the products of large operation experiences. So, the envelope type suspension clamps, which have abundant operating experience, are recommended for this project. .8.5 Spacers There are two types of spacers, one is the integral type, the other is spread assembled type. integral type spacers were adop ed for ultra high voltage line Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com (a) The traditionally designed Position limiting of clamp rotation (b) The design of double position limiting High strength bolts shall used for connecting tthe clamps and the body frames, that will to led convenient to replacing the clamps if needed. It is required that the Limit stop Double position limiting Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;vibration, only storage the energy by using the springs and then release it slowly. While by embed the elastomer in the joints, the elastomer damping type spacers will consume the energy of vibration, which obviously restrain the aeolian vibration and sub span oscillation. And as our exper ience, the effectiveness are perfect. To install the elastomer damping type spacers with unequal space is recommended. The clamp head of spacers may fall off and led to damaged under the huge forces of the rotation and dancing phenomena caused by coverin g ice in heavy ice zones, especially the jumping of conductors because of ice. That will effect the safe operating of the transmission lines. And there is already successful operating experience adopt preformed spacers to slove the problem As above li sting, elastomer damping type integral spacers are recommended in light ice zones, while preformed type spacers are recommended in heavy ice zones. (a) Spacers for light ice zones (b) Spacers for heavy ice zones Fig. 7 12 The recommended types of spacers 2.8.6 Equalizing ring, shielding ring For ultra high voltage ±800kV DC transmission line, because of the voltage level Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;increase, the number of insulators will be increase greatly than that of extra high voltage line. In insulator string, the voltage borne by single piece of insulator will also increase. For the safe working condition of the insulators, the voltage borne by single piece of insulator of ultra high voltage line shall not increased greatly compared with that of extra high voltage, that’s to say the required that voltage percentage borne by single piece of insulator of extra high voltage shall decrease, which requires a relatively great improvement in the design of corona ring. For the tension insulator strings, due to the coupling length is relatively long, with more the quantity of joining fittings, and the coupling type is complex, in order to elinimate the corona loss of the fittings, as well as the radio inference and audibl noise level, it’s necessary to proceed effective shield to the fittings of tension string. Guidance to the design and assembly of corona ring and shielding ring are as follows list: For suspension string and tension string, the installing position of grading ring is Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; Grading ring of tension string Shielding ring of tension string Figure 7 13 Gr ading ring and shielding ring of tension string .9 Suggestions (1) Suspension insulator in light pollution area may adopt disc type insulator or composite insulator, which shall chosen for configuring with the factors of climate conditions, operation e xperience and the type of insulator string. The insulator of suspension string in medium and heavy pollution area are adopt composite insulators. Tension insulator adopts disk type insulator. (2) It is recommended that adopt type V insulators as the main suspension string in the light ice area of this project, the angle of type V string in light ice area adopts 90~100°. For tangent angle tower, it is recommended to adopt type L insulator string. (3) Due to this project adopt duplex connection, and hinged Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ; &#x/MCI; 1 ;&#x/MCI; 1 ;(4) Tension string in light ice area of this project is recommended three connection horizo ntal arrangement for 400kN disc type insulator. (5) It is suggested that scientific research unit conduct the test of distance Hardware Web: www.JS Hardware.com , Email: sales@js hardware.com &#x/MCI; 0 ;&#x/MCI; 0 ;(4) It is recommended to adopt elastomer damping spacer for the light ice area, and preformed type spacer for the heavy ice area of this project. 5) For suspension string and tension string, the installing position of grading ring shall between the second and the third insulator, the voltage sharing result is