El Menia Farms Substation (66/22 KV, 2X40 MVA) PDF

EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA) CIS TYPE SECTION FOUR POWER TRANSFORMER AND ACCESSORIES a  EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA) CIS TYPE 4. POWER TRANSFORMERS AND ACCESSORIES...

EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA) CIS TYPE SECTION FOUR POWER TRANSFORMER AND ACCESSORIES a  EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA) CIS TYPE 4. POWER TRANSFORMERS AND ACCESSORIES TABLE OF CONTENTS CLAUSE DESCRIPTION Page 4.1. GENERAL 3 4.2. TYPE AND MAIN CHARACTERISTICS 3 4.3. LIMITS OF TEMPERATURE RISE 4 4.4. CONTINUOUS POWER RATING 4 4.5. LIMITED PERIODS RATING 4 4.6. ABILITY TO WITHSTAND SHORTCIRCUIT 5 4.7. EFFICIENCY AND LOSSES 5 4.8. HARMONICS 7 4.9. NOISE LEVEL 7 4.10. TRANSFORMER PARALLEL OPERATION 8 4.11. TRANSFORMER COOLING SYSTEM 8 4.12. TRANSFORMER CONSTRUCTION 10 4.13. ON LOAD TAP-CHANGER 12 4.14. OIL PRESERVATION SYSTEM 15 4.15. BUSHINGS 15 4.16. CURRENT TRANSFORMERS 16 4.17. OIL FOR TRANSFORMER 16 4.18. TRANSFORMER MONITOR AND PROTECTION 18 4.19. TERMINAL CABIENT 19 4.20. ACCESSORIES AND FITTINGS 19 4.21. REMOTE CONTROL AND PROTECTION 20 4.22. GAS PROTECTION 20 4.23. PROTECTION AGAINST EXCESSIVE HEATING 20 4.24. PROTECTION AGAINST HEATING OF TRANSFORMERS 20 4.25. PROTECTION AGAINST LOW OIL LEVEL 20 4.26. PAINTING 21 4.27. NAMEPLATES 21 4.28. MAINTENANCE MATERIALS 21 4.29. DRYING OUT OF TRANSFORMER 21 4.30. SUBMITTALS 21  EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA)CIS TYPE SECTION FOUR POWER TRANSFORMERS AND ACCESSORIES 4.1. General 4.1.1. The data and conditions specified in this chapter apply to the power transformers, accessories and fire fighting system. 4.1.2. The transformers shall be three phase oil immersed type and constructed in accordance with the latest edition of [IEC] standards unless otherwise specified hereinafter. 4.1.3. The transformers shall be transported with the tank under pressure of dry nitrogen gas and provided with pressure gauge suitably protected from damage. The pressure and temperature shall be recorded at the time of the transformer leaves the factory, the recorder information shall be given so that it can be compared with pressure and temperature readings after the transformer has been received at site to ascertain if any leakage has occurred. 4.1.4. Ensure that the transformer arrives at site in an uncontaminated condition. 4.1.5. Three axis impact recorders shall be provided on different places on the transformer to record any shocks, the capacity of the battery shall be sufficient to operate the impact recorder two months continuously, method of evaluating the shocks and places of the shocks recorders on the transformer to be submitted with tender the shocks recorders shall be protected from damage. 4.1.6. The transformers shall be unloaded either in Pre-determined storage area or on their foundations. 4.1.7. The manufacturer of the transformer and its main accessories should have ISO 9001 certificate, these certificates should be submitted with tender. 4.2. Type and main characteristics of the transformers: 4.2.1. The transformers shall be three phases, 50 Hz, Oil immersed, ONAN/ONAF cooling type, with on load tap changer suitable for outdoor tropical conditions. All power transformers of the above specified types shall be installed outdoor. 4.2.2. Ratings and characteristics of the transformers: Rating: 32/40 M.V.A Transformer ratio at main tap. And full load at 0.8 P.F: 66/22 KV 4.2.3. The transformer shall be operated and loaded safely, if the breakdown of the insulating oil is 40 K.V. / 2.5 mm gap. 4.2.4. All transformers shall be equipped with on-load tap changers, fans, radiators, oil conservators (expansion tanks), etc. 4.2.5. The star connection windings, neutral-bushing insulators shall be provided. 4.2.6. The principal tapping is the tapping corresponding to 100 % tapping factor. SECTION FOUR POWER TRANSFORMER AND ACCESSORIES Page (3) of (25)  EL MENIA FARMS SUBSTATION (66/22 KV, 2X40 MVA) GIS TYPE 4.3. Limits of temperature rise 4.3.1. The climatic conditions specified herein and the effect of operation in sunshine with high solar intensity for 12 hours per day shall be taken into consideration in the design of the transformers. 4.3.2. The transformers shall beetle to deliver the rated continuous power with the tap changer set at any tapping of the primary winding, without exceeding the following temperature rise limits over ambient temperature: 4.3.2.I. Winding temperature rise 50 °C (measured by resistance method) 4.3.2.2. Top oil temperature rise 45 °C (measured by thermometer at top level) 4.3.2.3. Hot spot temperature rise (by calculation, based on the highest winding's temperature and 60 °C Hotspot factor not less than 1.3) The winding maximum (hot spot) temperature shall not exceed 105 °C under normal loading conditions. The above temperature rise limits shall be based on the ambient temperature of 45° C. 4.3.3. The temperature rise will be measured on one transformer of each type to be delivered. If the temperature rise of this transformer exceeds the guaranteed figures a fine of 1.8 % of the total cost of the transformers of this type shall be imposed for every one degree higher than the guaranteed temperature rise. If the excess rise of temperature beyond than 5’C, E.E.T.C shall reject such transformers. 4.4. Continuous Power Rating 4.4.1. The transformers shall be able to deliver for an unlimited period of time at any tapping of the tap changer, the following continuous power ratings without exceeding the limits of temperature rise: 4.4.1.1. ONAN Cooling: up to 80%. 4.4.1.2. ONAF Cooling: >80%. 4.4.2. The continuous power ratings should be verified by the temperature rise test. 4.5. Limited Periods Rating 4.5.1. The transformer shall be capable of carrying 10% overload for two hours at any tapping, starting from steady state full load without exceeding the specified limits of temperature rise. 4.5.2. The limited periods rating should be verified by the temperature rise test by calculation is not accepted. ___________________ \ t »