Obra (Hydel), District : Sonebhadra, Uttar Pradesh

Installed capacity - 99 MW (3x33MW)

No. of units - 3








Sailent Features

Location Obra(District - Sonebhadra)
Name of River Rihand / Renuka
Name of Dam Obra Dam
Location of Dam 11km. upstream of confluence of Rihand/Renuka river with Sone river
DAM  
Type Earth and rock filled dam with spillway
Length on the Top & Top Width 2 km. & 10 M
Crest Length  
Main dam 450 M
Left dyke 577 M
Right dyke 575 M
Maximum height of dam above river bed 29.23 m.(excluding camber of 1.57 M)
No. & size of gates  15 nos, 10.4 M / (H) x 22.2 M (W)
Reservoir
Capacity at Normal Reservior Level 211 x 106 Cubic.M
Maximum reservoir level 193.30 M
Minimum reservoir level 192.65 M
Intake Structure Sluice Gate- 3 nos., each size 6.54M x 10.78 M)
Water Conductor system Penstock (3 Nos. pipes, each I.D. 7.925 M)
Power House & Control Room
Location Right Flank
Type Surface
Size L - 100 M., W - 23.11 M., at Top and 31.48 M at base
Height Above turbine floor - 21.30 M
Net / Rated / Design Head 20.4 M
Discharge of each machine at rated head 194 cumecs
Installed Capacity 3x33 MW - 99 MW
Turbine
Type Vertical Kaplan
HP 45300
Normal Speed 115.4 rpm
Specific Speed 572
Runner Dia 5.17m.
Efficiency 92.2 % at 75 % output
Governing System
Make H.E.(I) Ltd.
Type Hydro Mechanical
Designed Sensitivity .01 %
Governing System
Type Vertical Umbrella
KVA 36.67
Phase 3
KV 11
Hz 50
Power Factor 0.9 at 115.4 rpm.
Full Load Efficiency 97.06 %
Excitation Dynamic (Response Ratio 1.0)
Rating 296KW at 185V.
Tailrace
Type Open Type (Channel, Size - 5.2 M.x5.75 M)
TWL 173.28 M
Firm Power 33000 KW
Annual Design Energy 279 MU
Generating Voltage 11 kV
Transmission Voltage 132 kV
Switchyard
Incomers 3 Nos.
Outgoing Feeders 8 Nos.(132 kV)
Unit Transformers 3 Nos. (37.5 MVA, 11/132 kV), BHEL make
Auxiliary Transformers 3 Nos. (400 KVA, 11/0.4 kV), EMCO make
Station Transformers 2 Nos. (400 KVA, 11/0.4 kV), EMCO make
Name Plate Details of Turbine & Generator
Turbine of Unit No. 1, 2 & 3
Make HE(I) Ltd.
Type Vertical Kaplan,
Output 45,300 BHP
Speed 115.4rpm
Runway speed 213/259,
Year of Mrf. 1965
Generator of Unit No.-1
Make Associated Electrical Industries Ltd.
KVA 36,667
Volts 11 kV
Type ADV 360/55,
kW 33000
Amperes 1925
RPM 115.4
HZ 50
Volt Range 11000+10% - 5%
Year 1966
P.F. 0.9
Phase 3
Excitation Volt 135
Amperes 1343
Specification BS2613 1957:Class:B
Stator Connections Star
Generator of Unit No.-2 & 3
Make Heavy Electricals Ltd.
KVA 36,667
Volts 11 kV
Type ADV 360/55,
kW 33000
Amperes 1925
RPM 115.4
HZ 50
Volt Range 11000+10% - 5%
Year 1966
P.F. 0.9
Phase 3
Excitation Volt 135
Amperes 1343
Specification BS2613 1957:Class:B
Stator Connections Star
Note: In Unit No.- 3 Generator winding of B class has been replaced with F class in 1996 - 1998
 Cost Of the Project
2423.06 lacs
RENOVATION & MODERNIZATION SCHEME
S.No. Activity No. Brief Description of R&M Activity Original Sanction Cost
1 1 Renovation of Turbine of all the three units by way of
(i) Replacement of existing shaft gland system with new BHEL make LIP type Turbine rubber shaft seal assembly
(ii) Replacement of existing Hydro Mechanical Governor with latest Electro Hydraulic Governor
Rs. 200.00 Lacs
2 2 Replacement of old existing amplidyne of all the Three machines with new latest static Automatic Voltage Regular. RS 111.00 Lacs
3 3 Replacement of Slip ring of all the three units with new BHEL make slip rings RS 11.00 Lacs
4 4 Renovation of 132KV MOCBs of all the three units, 8 outgoing feeders & bus coupler with new SF-6 breakers RS 308.00 Lacs
5 5 Reinsulation of Generator Stator Coils and Rotor Poles Coils with 'F' Class Insulation RS 962.00 Lacs
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