standards / manuals / guidelines for small hydro development - AHEC

More documents

Recommendations

Info

The bus bar sizes should meet the electrical and mechanical requirements of thespecific application for which they are chosen.2.0 Circuit BreakersFor selection of circuit breakers refer section 4.Mounting and supporting structureThe circuit breakers should be self supporting type. However, if necessary for thepurpose of minimum ground clearance the circuit breakers should be mounted on raisedsteel structures which should be included in the scope of supply of circuit breaker.Information and data for design of foundations from the supplier of the circuit breaker beobtained.3.0 IsolatorsIsolating switches are used to isolate equipment for maintenance. Isolating switches online side are provided earthing blade for connection to earth in off position for safety.Transfer of load from one bus to another by isolators is not recommended. The isolatingswitches are designed for no load operation. Inadvertent operation of the isolating switchon load will damage the switch. Although a variety of disconnect switches are available,the factor which has the maximum influence on the station layout is whether thedisconnect switch is of the vertical break type or horizontal break type. Horizontal breaktype normally occupies more space than the verticalIsolators for 12 kV and 36 kV normal system voltage conform to IS: 9920 (Part I to IV)and for voltage 66 kV and above as per IS: 9921.Earthing switches is a mechanical switching device for earthing parts of a circuit, capableof withstanding fir a specified time short-circuit currents, but not required to carry normalrated currents of the circuit.Disconnecting switches may be motorized or operated manually it is recommended thatkV and above should be motorized. Earthing switches may be manually operated.In case of double circuit lines the earthing switches shall be capable of switchinginductive (electromagnetically) and capacitive currents (electrostatically induced) as perthe values specified in IEC 62271 – 102 when parallel circuit is energized. Thedisconnector must also be capable of interrupting and making parallel circuits whentransferring load between main and reserve bus bars according to IEC requirements.3.1 Temperature RiseMaximum temperature attained by any part of the isolating switch/ isolating cum-earthswitches when in service at site under continuous full load conditions and exposedcontinuously to the direct rays of the sun and the air has to be evaluated carefully and2-2
depends upon site conditions e.g. for 2 x 10 M Mukerian SHP 72.5 kV switchyard(Punjab Plains), it was specified as follows and is recommended for similar breakers.i) Reference ambient temperature in shade = 50 0 Cii) Reference temperature under direct rays = 60 0 Cof the sun for limiting temperature riseas per IS: 99213.2 RatingEach isolating switch should have the following particulars (table 2.3.2) under the siteconditions for the system under design.Table 2.3.21. Highest system voltage 72.5 kV 36 kV 12 kV2. Rated frequency (cycle/second) 50 c/s 50 c/s 50 c/s3. Rated lightning impulse withstand voltage (withoutarcing horn)i) To earth and between poles (kV Peak)ii) Across the isolating distance (kV peak)4. Rated one-minute power frequency wet withstandvoltagei) To earth and between poles (kV rms)ii) Across the isolating distance (kV rms)Voltage against ground and between poles2-3325 kV(+ ve & - ve waveto earth &between poles)140 kV(against ground &between poles)170 kV195 kV70 kV80 kV75 kV85 kV28 kV32 kV5. Continuous rated current (Amps) 1600 A 630 A 400 A6. Short time current ratingsi) For one second not less than kA (rms) 20 kA16 kA 16 kAii) For 3 secondsTo be stated To be To be7. Rated peak withstand current kA (peak) in closedpositionstated statedTo be stated 40 kA 40 kA8. Transformer off-load breaking capacity A (rms) To be stated 6.3 kA 6.3 kA9. Line charging capacity A (rms) To be stated 6.3 A 2.5 A10. Rated DC voltage for auxiliary circuits A (rms) To be stated11. Rated supply frequency and voltage of AC operatingdevicesIsolators 36 kV and 12 kV: should conform to IS: 9920Isolated 72.5 kV & above should conform to IS: 99213 phase 415 volts and single phase 220V ACThe location of disconnect switches in substations affects substation layouts.Maintenance of the disconnect contacts is also a consideration in the layout. In somesubstations, the disconnects are mounted at high positions either vertically orhorizontally. Although such substations occupy smaller areas, the maintenance of
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 12 and 13: Highest System Voltage rating kV Sp
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 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
Page 71 and 72: 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
Page 81 and 82:
5.7 Rated Short Circuit Making Curr
Page 83 and 84:
Effect of circuit conditions on rec
Page 85 and 86:
5.17 Rated time quantities and oper
Page 87 and 88:
25405017.5 812.516254024 812.516254
Page 89 and 90:
component of fault current in addit
Page 91 and 92:
Steps involved in applying method a
Page 93 and 94:
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-
show all

standards / manuals / guidelines for small hydro development - AHEC

Create successful ePaper yourself

Delete template?

Save as template?