BS IEC 60287-2-3:2017
$142.49
Electric cables. Calculation of the current rating – Thermal resistance. Cables installed in ventilated tunnels
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 26 |
This part of IEC 60287 describes a method for calculating the continuous current rating factor for cables of all voltages installed in ventilated tunnels. The method is applicable to any type of cable.
The method applies to natural as well as forced ventilation.
Longitudinal heat transfer within the cables and the surroundings of the tunnel is assumed to be negligible.
All cables are assumed to be identical within the tunnel and it is assumed that the tunnel cross-section does not change with distance along the tunnel.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 4 | English CONTENTS |
| 6 | FOREWORD |
| 8 | INTRODUCTION |
| 9 | 1 Scope 2 Normative references 3 Terms, definitions and symbols 3.1 Terms and definitions 3.2 Symbols |
| 11 | 4 Description of method 4.1 General description |
| 12 | 4.2 Basic formulae 4.2.1 General 4.2.2 Radial heat transfer by conduction within the cable |
| 13 | 4.2.3 Heat transfer by radiation from the cable surface to the inner wall of the tunnel 4.2.4 Heat transfer by convection from the cable surface to the air inside the tunnel Tables Table 1 – Fm coefficient for radiation thermal resistance calculation |
| 14 | 4.2.5 Heat transfer by convection from the air inside the tunnel to the inner tunnel wall Table 2 – Value of parameter Kcv |
| 15 | 4.2.6 Longitudinal heat transfer by convection resulting from the forced or natural flow of air along the tunnel 4.2.7 Radial heat conduction in the soil surrounding the tunnel |
| 16 | 4.3 Set of formulae 4.4 Solving |
| 17 | 4.5 Iterative process |
| 18 | 5 Formulae for air properties 6 Temperature profile |
| 19 | Annex A (informative) Calculation example A.1 Cable and installation A.2 Calculated values Table A.1 – Installation data |
| 20 | Table A.2 – Iterative process for a 1 km long tunnel |
| 21 | Figures Figure A.1 – Temperature profile along a 1 km tunnel Figure A.2 – Temperature profile along a 10 km tunnel |
| 23 | Annex B (informative) Delta-star transformation Figure B.1 – Delta-star transformation |
| 24 | Annex C (informative) Calculation of Fm coefficient C.1 Definition of spacing C.2 Calculation of Fm coefficient Figure C.1 – Spacing definitions Table C.1 – Expression for Fm coefficient calculation |
