The mechanical effects of short-circuit currents in - Montefiore

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IEC 60865 Calculations If the clearance time is taken equal Tk=Tk1 + Tk2=0.175 s, IEC standard calculations give the following values : Ft=13816N, Ff=24235N span IEC Appendix tests 68 m 865 1 Ft N 13816 9676 11432 Ff N 24235 22469 22051 Table 8.2 : Comparisons between tests and calculations 132
8.6. FLOW CHARTS TO THE STANDARDISED METHOD FOR RIGID BUSBARS In paragraph 2.2, the formulas are listed and the background is described for the estimation of the short-circuit strength of busbars with rigid conductors according to the standard IEC/EN 60865-1 [Ref 2], [Ref 3]. For better clearness, the flow charts of the procedure are performed in this chapter with and without calculating the relevant frequencies. The flow charts are divided in several parts to show the foregoing for single main conductors as well as for main conductors consisting of sub-conductors. In the statements, the equations [(...)], figures [F...] and tables [T...] of the standard are cited. ‘reclosing’ means three-phase automatic reclosing. The statements are to execute in the given order. They are suitable for three-phase systems as well as for single-phase two-line systems; at this F m is either F m3 or F m2. For the yield point of conductor materials the actual values should be used. If only minimum and maximum values are available, R p0,2 is the minimum value and R’ p0,2 the maximum value. If there is no three-phase automatic reclosing used in the network, – with calculation of the conductor frequencies the parts a) to e) – without calculation of the conductor frequencies the parts a) to d) are to be passed and the calculation is finished when reaching END 1. If three-phase automatic reclosing is used in the system, there is a first short-circuit current flow, a dead time and after this a second short-circuit current flow if the reclosing is unsuccessful which has to be taken into account for short-circuit withstand. Determining according to the standard, the conductor stresses and the forces on the support are calculated during the second short-circuit current flow. In this case, – with calculation of the conductor frequencies the parts a), b), c), f) and g) – without calculation of the conductor frequencies the parts a), b), e) and f) 133 are to be passed with neglect of the statements in the dotted boxes. The calculation is finished when reaching END 2. In paragraph 2.2.3 it is shown that the conductor stresses are greater in the second current flow according to Table 2 of the standard and can be greater according to Figures 4 and 5 of the standard with relevant frequencies. This can cause higher forces on the supports during the first current flow. Therefore it is recommended to follow the complete flow chart including the statements in the dotted boxes which compare the forces at the supports during the first and second current flow: – if VF Vr > 1 and VF > 1 follows from Figures 4 and 5 of the standard with calculation of the conductor frequencies, – and always without calculation of the conductor frequencies. In the flow chart, four flags STOP 1 to STOP 4 are included. When they are reached, the stresses in the conductors is too high and modifications in design are necessary: STOP 1: The sub-conductors do not withstand. Either the distance between two adjacent spacers is too large or the subconductors are too small. STOP 2: The main conductors do not withstand. Either the distance between two adjacent supports is too large or the main conductors are too small. STOP 3: The sub-conductors do not withstand in the case of three-phase automatic reclosing. Either the distance between two adjacent spacers is too large or the subconductors are too small. STOP 4: The main conductors do not withstand in the case of three-phase automatic reclosing. Either the distance between two adjacent supports is too large or the main conductors are too small. For better design, it is recommended to do the calculation always considering the relevant frequencies of the conductors especially in the case of HV- and UHV-busbars which have low frequencies. In the following, the flow charts are given for the determination of the short-circuit stresses and forces with and without calculating the relevant conductor frequencies:
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THE MECHANICAL EFFECTS OF SHORT-CIR
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3.7. Special problems .............
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1. INTRODUCTION 1.1. GENERAL PRESEN
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The pinch (first maximum) can be ve
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1.3.3.2 Supporting structures Simil
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This method allows to state the sho
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and becomes the static force in equ
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(2.26) M el-pl ⎡ y d/ 2 y = 2⎢
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V σ 3 2,5 2 1,5 1 mechanical reson
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V F 3 2,5 2 1,5 1 mechanical resona
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1. eigenmode 2. eigenmode 3. eigenm
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(2.43) U E max max = 1 2 1 = 2 l
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m (2.47) M = σm = Z mσ m dm 2 J w
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profiles in Figure 2.14 it follows
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(2.71) 2 tube tube 4 tube U ∂U
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2.3.2. Influence of two busbars a)
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Asymmetrical associated-phase layou
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d)Methods used IEC 60865 method : -
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Section 3.4 deals with the effects
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In Figure 3.5 to Figure 3.8, the ma
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Figure 3.17 Comparison calculated a
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movement of the dropper (swing out
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This value has to be compared with
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EN 60865-1 [Ref 3] with the assumpt
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a) b) c) 3 m 2 1 0 -1 δ m δ 1 Mov
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Droppers with fixed upper ends Duri
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Manuzio developed a simplified meth
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From prior tests the stiffness valu
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Force / kN Force / kN 100mm 200mm 4
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1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 ESL F
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3.7. SPECIAL PROBLEMS 3.7.1. Auto-r
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for the maximum outswing and the ma
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Zug-/Druck-Kraft in kN Z eit in s F
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The numerical resolution of these e
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4. GUIDELINES FOR DESIGN AND UPRATI
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standards and tested under specifie
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5. PROBABILISTIC APPROACH TO SHORT-
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f G f(L) Lt Ls 75 G(L) ∞ R = ∫
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Only the lowest break values are im
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5.2.2. A global Approach For analyz
Page 82 and 83: to multinode operation can compared
Page 84 and 85: 5.2.3.1.7. Proposed Approach The st
Page 86 and 87: The first case (Figure 5.14) corres
Page 88 and 89: centers are normally balanced by ba
Page 90 and 91: Remark: The risk integral (5.3) can
Page 92 and 93: 1,0 0,8 0,6 0,4 0,2 0,0 -0,2 -0,4 -
Page 94 and 95: The histograms below for the instan
Page 96 and 97: 5.2.3.8.2. Reliability based design
Page 98 and 99: power converter in a three phase br
Page 100 and 101: The time functions of the currents
Page 102 and 103: a) Determination of the linear mome
Page 104 and 105: Figure 6.11 Coefficients mJs1 and m
Page 106 and 107: 7. REFERENCES Ref 1. IEC TC 73/CIGR
Page 108 and 109: Ref 42. Stein, N.; Miri, A.M.; Meye
Page 110 and 111: Ref 80. Fiabilité des structures d
Page 112 and 113: 8. ANNEX 8.1. THE EQUIVALENT STATIC
Page 114 and 115: Figure 8.2 What is ESL in this case
Page 116 and 117: As the eigenfrequency of the portal
Page 118 and 119: Figure 8.9 Case 3 (third eigenfrequ
Page 120 and 121: Both cases have the same 200-kV-arr
Page 122 and 123: a) c) 5 +25 % 0 % 4 3 F c / F st 2
Page 124 and 125: a) b) 24 kN 20 +25 % 0 % 2,0 m F c
Page 126 and 127: Case *11 (EDF 1990) This is the 102
Page 128 and 129: 8.4. INFLUENCE OF THE RECLOSURE The
Page 130 and 131: ( ( δ ) ( δ ) ) T = Mg08 . b r .
Page 134 and 135: 8.6.1.1 With calculation of the rel
Page 136 and 137: f) Calculation of the stresses due
Page 138 and 139: d) Determination of the forces at t
Page 140 and 141: 8.7. ERRATA TO BROCHURE NO 105 In V
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The mechanical effects of short-circuit currents in - Montefiore

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