IEC TS 62257-9-2:2016(E) specifies microgrids made of overhead lines because of technical and economical reasons in the context of decentralized rural electrification. The microgrids covered by this part of IEC 62257 are low voltage AC, three-phase or single-phase, with rated capacity less than or equal to 100 kVA. They are powered by a single micropower plant. The main technical changes with regard to the previous edition are as follows: changing the voltage range covered by the technical specification to AC nominal voltage below 1 000 V and DC nominal voltage below 1 500 V. This publication is to be read in conjunction with \/2.<\/p>\n
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| 4<\/td>\n | CONTENTS <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | 1 Scope 2 Normative reference 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 4 General 4.1 Limits of a microgrid 4.2 Voltage drops 4.3 Composition of a microgrid Figures Figure 1\u00a0\u2013 Microgrid limits Tables Table 1 \u2013 Maximum values of voltage drops <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Figure 2 \u2013 Microgrid consisting of a single phase feeder Figure 3 \u2013 Three phase system output, single phase distribution or three phase service provided where needed Figure 4 \u2013 Three phase system output, single phase distribution <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 5 Protection against electric shocks 6 Protection against overcurrents 7 Selection and erection of equipment 7.1 Equipment installation 7.2 Operational conditions and external influences 7.2.1 Ambient temperature 7.2.2 Sources of heat 7.2.3 Presence of water <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 7.2.4 Risk of penetration of solid bodies 7.2.5 Corrosive or polluting substance presence 7.2.6 Mechanical requirements 7.2.7 Equipment and supporting structures 7.2.8 Vibration 7.2.9 Other mechanical constraints for underground microgrid sections <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 7.2.10 Presence of flora, mold or fauna 7.2.11 Solar radiation 7.3 Characteristics of lines 7.3.1 General 7.3.2 Installation modes 7.3.3 Minimum height of conductors 7.3.4 Proximity to other services 7.4 Cables <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 7.5 Poles 7.5.1 General 7.5.2 Characteristics of poles <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Figure 5 \u2013 Diagram showing installation of twinned wooden poles forming an angle <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 7.6 Cable anchorage Figure 6 \u2013 Examples of different pole arrangements Figure 7 \u2013 Example of an overhead line <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | 7.7 Connections and accessories 7.7.1 General 7.7.2 Connections between conductors, connections to other equipment 7.7.3 Connection points for individual service connections 7.7.4 Connection equipment <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 7.8 Where poles are used for other purposes 7.8.1 Public lighting points 7.8.2 Telecommunication lines Figure 8 \u2013 Connection mode diagram <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | 7.9 Isolation and switching 7.9.1 Overcurrent protection device Table 2 \u2013 Fuse ratings for protection from short-circuiting in 230 V (and 240 V) a.c. microgrids (overhead lines) Table 3 \u2013 Fuse ratings for protection from short-circuiting in 120 V a.c. microgrids (overhead lines) Table 4 \u2013 Circuit breaker ratings for protection from short-circuiting in microgrids (overhead lines) <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 7.9.2 Isolating devices 7.10 Earthing arrangement, protective conductors and protective bonding conductors Figure 9 \u2013 Microgrid earthing scheme <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 8 Verification and acceptance 8.1 General 8.2 Supervision of works Table 5 \u2013 Characteristics of earthing components <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 8.3 Verification before commissioning (on site acceptance) 8.4 Operation tests <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Annex A (informative) Characteristics of cables Table A.1 \u2013 Example of characteristics of grid conductors for overhead lines (insulated twisted conductors without carrier neutral) (1 of 2) <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Annex B (informative) Maximum circuit length <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Figure B.1 \u2013 Maximum lengths as a function of active power (1 phase) for 16 mm2 cable and 6 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure B.2 \u2013 Maximum lengths as a function of active power (1 phase) for 16 mm2 cable and 6 % voltage drop with loads spread across cable <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Figure B.3 \u2013 Maximum lengths as a function of active power (1 phase) for 25 mm2 cable and 6 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Figure B.4 \u2013 Maximum lengths as a function of active power (1 phase) for 25 mm2 cable and 6 % voltage drop with loads spread across cable <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Figure B.5 \u2013 Maximum lengths as a function of active power (3 phase) for 35 mm2 cable and 6 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Figure B.6 \u2013 Maximum lengths as a function of active power (3 phase) for 35 mm2 cable and 6 % voltage drop with loads spread across cable <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Figure B.7 \u2013 Maximum lengths as a function of active power (3 phase) for 35 mm2 cable and 3 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Figure B.8 \u2013 Maximum lengths as a function of active power (3 phase) for 50 mm2 cable and 6 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | Figure B.9 \u2013 Maximum lengths as a function of active power (3 phase) for 50 mm2 cable and 6 % voltage drop with loads spread across cable <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | Figure B.10 \u2013 Maximum lengths as a function of active power (3 phase) for 50 mm2 cable and 3 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Figure B.11 \u2013 Maximum lengths as a function of active power (3 phase) for 70 mm2 cable and 6 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | Figure B.12 \u2013 Maximum lengths as a function of active power (3 phase) for 70 mm2 cable and 6 % voltage drop with loads spread across cable <\/td>\n<\/tr>\n | ||||||
| 41<\/td>\n | Figure B.13 \u2013 Maximum lengths as a function of active power (3 phase) for 70 mm2 cable and 3 % voltage drop with loads at end of cable <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Recommendations for renewable energy and hybrid systems for rural electrification – Integrated systems. Microgrids<\/b><\/p>\n |