standards / manuals / guidelines for small hydro development - AHEC

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Highest System Voltage rating kV Spacing between phases in mm245 kV 4500145 kV 360072.5 kV 220036 kV 130012 kV 1300 or 920The spacings for the equipment in a sub-station depend upon the manufacturerspractice.The minimum clearance of live parts to ground in an outdoor sub-station are as follows(Tamil Nadu Practice):Highest System VoltageClearances in mm245 kV 5500145 kV 460072.5 kV 460036 kV 370012 kV 3700The bottom most portion of any insulator or bushing in service should be at anabsolute minimum height of 2500 mm above ground level.2.4.4 Section ClearancesA station which can not be shunt down entirely for maintained purpose must be split intosections so arranged that any one section can be isolated from its neighbour withadequate clearances as given below. Where it is impossible to obtain the required safetyclearances, earthed screens may be provided.The following table gives the sectional clearances for persons to enable inspectioncleaning, repairs; painting and general maintenance works to be carried out in a substation.Highest SystemVoltageSection Clearances145 kV 3500 mm72 kV 3000 mm36 kV 2800 mm12 kV 2600 mmThe following minimum clearances should be adopted for enclosed indoor busbarsand connections in air which are not filled with any insulating medium like compoundetc.Highest System voltage betweenphases or polesMinimum clearances in Air1-11
Between phases or Phase/pole to earthpoles36 kV 356 mm 222 mm12 kV 127 mm 76 mmIn indoor kiosks in power stations and main receiving stations, the busbar andconnections should also be taped but the fact of taping should however, be taken intoconsideration in deciding the clearances. In addition indoor kiosks etc. should besubjected to a flashover test at works to prove that clearances are adequate so as toprevent flashovers during surge conditions.2.4.5 Standard Bay Widths (in meters) as TNEB Practices66 kV - 733kV - 4.622 kV - 3.811 kV - 3.52.5 Insulators – Creepage DistanceProvision of adequate insulation in a substation is of primary importance from the pointof view of reliability of supply and safety of personnel. However, the station designshould be so evolved that the quantity of isolators required is minimum commensuratewith the expected security of supply. An important consideration in determining theinsulation in a sub-station, particularly if it is located near sea or a thermal powergenerating station or an industrial plant is the level of pollution. As a first step to combatthis problem, special insulators with higher creepage distance should be used.The creepage distances for the different pollution levels are provided according to table2.8.Table 2.8: Creepage distance for different pollution levelsPollution LevelCreepage distance (mm/kV ofhighest system voltage)Recommendedfor adoptedLight 16 25 x highestMedium 20system voltageHeavy 25i.e. 1813 mmVery heavy 31for 72.5 kVFor determining the creepage distance requirement, the highest line-to-line voltage of thesystem forms the basis.1-12
Page 2 and 3: Section -1Guide for Design of Outdo
Page 4 and 5: The terms atmospheric overvoltages
Page 6 and 7: Table 2.31. Basic Data Example 1.Hi
Page 8 and 9: Spark gaps specified for fitting to
Page 10 and 11: 2.4.2 Working Safety Clearances125
Page 14 and 15: 2.6 Insulator TypeTypes of insulato
Page 16 and 17: Bending .. .. 1265 kg/sq.cm.Shear .
Page 18 and 19: v) Installations in difficult site
Page 20 and 21: During maintenance, it is essential
Page 22 and 23: Areva Compact Air Insulated Substat
Page 24 and 25: The bus bar sizes should meet the e
Page 26 and 27: disconnect switch contacts in such
Page 28 and 29: (iv)Electro magnetic type interlock
Page 30 and 31: ) Temperature rise of 11 kV Class C
Page 32 and 33: 4.6 TestsThe CTs shall be provided
Page 34 and 35: 10. 1.2/50 micro seconds impulse 32
Page 36: 7.0 Lightning ArrestorsLightning ar
Page 39 and 40: and this aspect has to be kept in m
Page 41 and 42: Fig. 12.1: Layout of 12 kV Agnoor S
Page 43 and 44: Fig. 12.4 Layout of 72.5 kV Switchy
Page 45 and 46: 464006800 7600 3000LA30002000 2000X
Page 47 and 48: Fig. 12.6:145 kV Outdoor Switchyard
Page 49 and 50: Fig. 12.7: 245 kV Outdoor Switchyar
Page 51 and 52: 2-20
Page 53 and 54: 3.0 Transformer RatingThe full load
Page 55 and 56: OFAFOil Immersed with forced oil ci
Page 57 and 58: The transformer may be operated wit
Page 59 and 60: 8.10 Parallel OperationThe transfor
Page 61 and 62: (a)(b)33 kV Transformers (MVA)1.001
Page 63 and 64:
(e)(f)(g)(h)(i)(j)(k)(l)(m)(n)(o)(p
Page 65 and 66:
18.0 Oil Containment and Fire Prote
Page 67 and 68:
) The limits of temperature rise me
Page 69 and 70:
Example Calculation -1Generator Tra
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TRANSFORMER RATING AND CHARACTERSTI
Page 73 and 74:
3.0 Type of Circuit BreakerFollowin
Page 75 and 76:
iii) during arcing of SF6 breaker,
Page 77 and 78:
3.4 Protection Classes for Switchge
Page 79 and 80:
The rated voltage is expressed in k
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5.7 Rated Short Circuit Making Curr
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Effect of circuit conditions on rec
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5.17 Rated time quantities and oper
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25405017.5 812.516254024 812.516254
Page 89 and 90:
component of fault current in addit
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Steps involved in applying method a
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to earthxvii. Difference in the ins
Page 95 and 96:
Datai) Sub transient reactance of g
Page 97 and 98:
Annexure-1Current waveAA = envelop
Page 99:
Annexure-3Fig. 3.3 Arc extinction4-
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