IEC TR 60865-2:2015

Short-circuit currents - Calculation of effects - Part 2: Examples of calculation

IEC TR 60865-2:2015(E) shows the application of procedures for the calculation of mechanical and thermal effects due to short circuits as presented in IEC 60865-1. Thus, this technical report is an addition to IEC 60865-1. It does not, however, change the basis for standardized procedures given in that publication. This second edition cancels and replaces the first edition published in 1994 and constitutes a technical revision. It includes the following changes. The determinations for auto reclosure together with rigid conductors have been revised. The configurations in cases of flexible conductor arrangements have been changed. The influence of mid-span droppers to the span has been included. For vertical cable-connection the displacement and the tensile force onto the lower fixing point may be calculated now. Additional recommendations for foundation loads due to tensile forces have been added. The subclause for determination of the thermal equivalent short-circuits current has been deleted (is part of IEC 60909-0:2001 now). The standard IEC 60865-1:2011 has been reorganized and some of the symbols have been changed to follow the conceptual characteristic of international standards.

General Information

• Status: Published
• Publication Date: 21-Apr-2015
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: TC 73 - Short-circuit currents
• Current Stage: PPUB - Publication issued
• Start Date: 15-Apr-2015
• Completion Date: 22-Apr-2015

Standards Content (Sample)

IEC TR 60865-2 ®
Edition 2.0 2015-04
TECHNICAL
REPORT
Short-circuit currents – Calculation of effects –
Part 2: Examples of calculation
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IEC TR 60865-2 ®
Edition 2.0 2015-04
TECHNICAL
REPORT
Short-circuit currents – Calculation of effects –

Part 2: Examples of calculation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.01; 29.240.20 ISBN 978-2-8322-2551-6

– 2 – IEC TR 60865-2:2015 © IEC 2015
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Symbols and units . 7
4 Example 1 – Mechanical effects on a 10 kV arrangement with single rigid
conductors . 8
4.1 General . 8
4.2 Data . 9
4.3 Normal load case: Conductor stress and forces on the supports caused by
dead load . 9
4.4 Exceptional load case: Effects of short-circuit currents . 10
4.4.1 Maximum force on the central main conductor . 10
4.4.2 Conductor stress and forces on the supports . 11
4.5 Conclusions . 13
5 Example 2 – Mechanical effects on a 10 kV arrangement with multiple rigid
conductors . 14
5.1 General . 14
5.2 Data (additional to the data of Example 1) . 14
5.3 Normal load case: Conductor stress and forces on the supports caused by
dead load . 15
5.4 Exceptional load case: Effects of short-circuit currents . 15
5.4.1 Maximum forces on the conductors . 15
5.4.2 Conductor stress and forces on the supports . 16
5.5 Conclusions . 20
6 Example 3. – Mechanical effects on a high-voltage arrangement with rigid
conductors . 20
6.1 General . 20
6.2 Data . 21
6.3 Normal load case: Conductor stress and forces on the supports caused by

dead load . 22
6.4 Exceptional load case: Effects of short-circuit currents . 23
6.4.1 Maximum force on the central main conductor . 23
6.4.2 Conductor stress and forces on the supports . 23
6.4.3 Conclusions . 29
7 Example 4. – Mechanical effects on a 110 kV arrangement with slack conductors . 30
7.1 General . 30
7.2 Data . 31
7.3 Electromagnetic load and characteristic parameters . 32
7.4 Tensile force F during short-circuit caused by swing out . 34
t,d
7.5 Dynamic conductor sag at midspan . 35
7.6 Tensile force F after short-circuit caused by drop . 36
f,d
7.7 Horizontal span displacement b and minimum air clearance a . 36
h min
7.8 Conclusions . 36
8 Example 5. – Mechanical effects on strained conductors . 37
8.1 General . 37
8.2 Common data . 37
8.3 Centre-line distance between sub-conductors a = 0,1 m . 38
s
8.3.1 Electromagnetic load and characteristic parameters . 38
8.3.2 Tensile force F during short-circuit caused by swing out . 41
t,d
8.3.3 Dynamic conductor sag at midspan . 41
8.3.4 Tensile force F after short-circuit caused by drop . 42
f,d
8.3.5 Horizontal span displacement b and minimum air clearance a . 43
h min
8.3.6 Pinch force F . 43
pi,d
8.3.7 Conclusions . 43
8.4 Centre-line distance between sub-conductors a = 0,4 m . 44
s
8.4.1 Preliminary remarks . 44
8.4.2 Characteristic dimensions and parameters . 44
8.4.3 Pinch force F . 45
pi,d
8.4.4 Conclusions . 47
9 Example 6 – Mechanical effects on strained conductors with dropper in the middle
of the span . 47
9.1 General . 47
9.2 Common data . 48
9.3 Plane of the dropper parallel to the main conductors . 48
9.3.1 General . 48
9.3.2 Current flow along the whole length of the main conductor span . 49
9.3.3 Current flow along half of the length of the main conductor and along the
dropper . 57
9.4 Plane of the dropper perpendicular to the main conductors . 64
9.4.1 General . 64
9.4.2 Current flow along the whole length of the main conductor span . 64
9.4.3 Current flow along half of the length of the main conductor and along the
dropper . 69
10 Example 7 – Mechanical effects on vertical main conductors (droppers) . 77
10.1 General . 77
10.2 Data . 77
10.3 Short-circuit tensile force and maximum horizontal displacement . 78
10.4 Pinch force . 78
10.4.1 Static tensile force regarding droppers . 78
10.4.2 Characteristic dimensions and parameters . 79
10.4.3 Pinch force F . 80
pi,d
10.5 Conclusions . 81
11 Example 8 – Thermal effect on bare conductors . 81
11.1 General . 81
11.2 Data . 81
11.3 Calculations . 82
11.4 Conclusion . 82
Bibliography . 83

Figure 1 – Conductor arrangement . 8
Figure 2 – Position of the sub-conductors and connecting pieces . 14
Figure 3 – Two-span arrangement with tubular conductors. 21
Figure 4 – Arrangement with slack conductors . 31
Figure 5 – Arrangement with strained conductors . 37
Figure 6 – Arrangement with strained conductors and droppers in midspan. Plane of the

droppers parallel to the main conductors . 47

– 4 – IEC TR 60865-2:2015 © IEC 2015
Figure 7 – Possible arrangement of perpendicular droppers in three-phase system and
two-line system . 64
Figure 8 – Arrangement with strained conductors
...