BSI 15/30320260 DC:2015 Edition
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BS EN 60076-7. Power transformers. Part 7. Loading guide for liquid-immersed power transformers
| Published By | Publication Date | Number of Pages |
| BSI | 2015 | 85 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | 30320260 |
| 10 | 14_807e_CD 1 Scope 2 Normative references 3 Terms and definitions |
| 12 | 4 Symbols and abbreviations |
| 14 | 5 Effect of loading beyond nameplate rating 5.1 Introduction |
| 15 | 5.2 General consequences 5.3 Effects and hazards of short-time emergency loading |
| 16 | 5.4 Effects of long-time emergency loading |
| 17 | 5.5 Transformer size |
| 18 | 6 Relative ageing rate and transformer insulation life 6.1 General 6.2 Insulation life |
| 23 | 6.3 Relative ageing rate |
| 24 | 6.4 Loss-of-life calculation |
| 25 | 7 Limitations 7.1 Temperature limitations |
| 26 | 7.2 Current limitations 7.3 Specific limitations for distribution transformers 7.3.1 Current and temperature limitations 7.3.2 Accessory and other considerations 7.3.3 Indoor transformers 7.3.4 Outdoor ambient conditions |
| 27 | 7.4 Specific limitations for medium-power transformers 7.4.1 Current and temperature limitations 7.4.2 Accessory, associated equipment and other considerations 7.4.3 Short-circuit withstand requirements 7.4.4 Voltage limitations 7.5 Specific limitations for large power transformers 7.5.1 General |
| 28 | 7.5.2 Current and temperature limitations 7.5.3 Accessory, equipment and other considerations 7.5.4 Short-circuit withstand requirements 7.5.5 Voltage limitations |
| 29 | 8 Determination of temperatures 8.1 Hot-spot temperature rise in steady state 8.1.1 General 8.1.2 Calculation of hot-spot temperature rise from normal heat-run test data |
| 31 | 8.1.3 Direct measurement of hot-spot temperature rise |
| 34 | 8.1.4 Hot-spot factor |
| 36 | 8.2 Top-oil and hot-spot temperatures at varying ambient temperature and load conditions 8.2.1 General |
| 37 | 8.2.2 Exponential equations solution |
| 42 | 8.2.3 Difference equations solution |
| 44 | 8.3 Ambient temperature 8.3.1 Outdoor air-cooled transformers 8.3.2 Correction of ambient temperature for transformer enclosure |
| 45 | 8.3.3 Water-cooled transformers 9 Influence of tap changers 9.1 General |
| 46 | 9.2 Short-circuit losses 9.3 Ratio of losses 9.4 Load factor |
| 47 | Annex A (informative) Ageing Relative ageing rate considering oxygen and water effect A.1 Insulation life expectancy |
| 49 | A.2 Relative ageing rate considering oxygen and water effect |
| 51 | Annex B (informative) Core temperature B.1 Introduction B.2 Core hot-spot locations |
| 52 | Annex C (informative) Specification of loading beyond rated power |
| 54 | Annex D (informative) Description of Q, S and H factors |
| 57 | Annex E (informative) Calculation of winding and oil time constant |
| 59 | Annex F (informative) Thermal model parameters F.1 Introduction F.2 Thermal constant estimation: experimental approach |
| 62 | F.3 Dynamic thermal modelling: further development |
| 63 | Annex G (informative) Practical example of the exponential equations method G.1 Introduction |
| 64 | G.2 Time period 0 min to 190 min G.3 Time period 190 min to 365 min |
| 65 | G.4 Time period 365 min to 500 min G.5 Time period 500 min to 705 min |
| 66 | G.6 Time period 705 min to 730 min G.7 Time period 730 min to 745 min G.8 Comparison with measured values |
| 69 | Annex H (informative) Application of the difference equation solution method H.1 Introduction H.2 Example |
| 74 | H.6 Use of measured top-oil temperature |
| 75 | Annex I (informative) Flowchart, based on the example in Annex G |
| 77 | Annex J (informative) Example of calculating and presenting overload data |
| 81 | Annex K (informative) Geomagnetic induced currents |
| 82 | Bibliography |
