standards / manuals / guidelines for small hydro development - AHEC

(a)(b)33 kV Transformers (MVA)1.001.603.154.005.006.308.0010.0066 kV Transformers (MVA)6.38.010.012.520.01.82.13.24.04.65.46.17.26.07.18.49.713.08142224273344534048577010211.0 Terminal BushingsConnections for the generator transformers are mostly by power cables for small hydrostations upto 10 MVA rating from generator terminals to power transformer inswitchyard. Bus ducts which could be isolated phase for large units or segregated phasebus ducts for smaller units may be used. Accordingly terminal for the generatortransformers should be as follows:LV Side: LV bushings should be mounted on turrets suitable for connection to busbar in bus ducts. For SHP cable boxes may be provided, if cables are used.HV Side: Solid Porcelain/Oil Communicating and other type bushings upto 36 kVvoltage class in accordance with IS: 3347. The dimensional parameters of the bushingsupto and including 36 kV voltage class should be in accordance with IS: 3347. The ratedcurrent, voltage, Basic Insulation Levels should be in accordance with IS: 2099.66 kV to 220 kV bushings are oil impregnated paper (OIP) type condenser bushings inaccordance with IS 2099 and IEC 137. Dimensions interchange capability current,insulation level and creepage distance for various classes of the bushings should be inaccordance with CBI & P Manual on transformers Section P.The electrical characteristics of bushing insulator shall be in accordance with IS: 2099 asamended from time to time. All type and routine tests shall be carried out in accordancewith IS: 2099. The test voltage for various tests as stipulated in IS: 2099 – 1986 are asfollows:NominalsystemvoltageRated voltage of thebushingOne minute wet anddry power frequencyvoltage withstand testLightning impulsewithstand test 12/50micro sec. kV peak3-10