DATE: - 02-06-2015 TO 01-07-2015PREPARED BY:ADITYA BALUNI B.TECH ELECTRICAL ENGINEERING DEHRADUN INSTITUTE OF TECHNOLOGY DEHRADUN Date:21/08/2015 SUBMITTED TO: Mr. MOHIT BAJAJ (Asst. Professor) 1 (Electrical Dept.) ACKNOWLEDGEMENTS First and foremost, I would like to express my gratitude towards our HR AND TRG. PLACEMENT HEAD for giving me this wonderful opportunity to research in this area and directing and supporting me at every step in this endeavor. I would also like to thank all the Engineers & Managers of THDC, Tehri for their genuine interest in the report, valuable inputs, patience and constructive criticism. I also take this opportunity to thank all the informants who agreed to help me in the study and for taking their precious time out to provide me the material without which compilation of this report would not have been possible. 2 TABLE OF CONTENTS S.NO. 1. a) b) c) d) e) f) g) 2. a) i) ii) CONTENTS INTRODUCTION ABOUT CORPORATION BACKGROUND OBJECTIVES VISION MISSION DAM SPILLWAYS INTERMEDIATE LEVEL OUTLET (ILO) POWER HOUSE FEATURES OF POWER HOUSE EXERTION MACHINE HALL PAGENO. 5 5 5 5 5-6 6-7 8-11 11 12-19 12 12 CONTROL ROOM (CCS) 13 iii) HEAD RACE TUNNEL (HRT) 13-14 iv) VENTILATION SYSTEM 14 v) PENSTOCK ASSEMBLY CHAMBER(PAC) 15 vi) BUTTERFLY VALVE CHAMBER (BVC) 15 vii) MAIN CARVEN 16 viii) EXCITATION SYSTEM 16-17 ix) TAIL RACE TUNNELS (TRTs) 18 COOLING SYSTEM 18 xi) FIRE FIGHTING SYSTEM 19 x) 3 xii) UNIT CONTROL BOARD 19 xiii) DIVERSION TUNNELS 20 3. a) b) 4. a) b) c) d) 5. 6. a) b) c) 7. 8. 9. 10. 11. 12. 13. 14. TECHNICAL DATA OF GENERATOR BRAKING SYSTEM SPECIFICATION OF THE GENERATOR PUMP STORAGE PLANT (PSP) PROJECT FEATURE STATUS COST TARRIF ADVANTAGE OF PSP ELECTROMECHANICAL EQUIPMENT MAINTENANCE: TURBINE AND ITS AUXILLARIES Turbine GOVERNOR GENERATOR AND ITS AUXILIARIES TRANSFORMERS AND SWITCHYARD BLACK START OPERATION SYNOPSIS TECHNICAL REQUIREMENTS BLACK START SEQUENCE: LIMITATIONS OF BLACK START OPERATION DISTRIBUTION SYSTEM TECHNICAL SPECIFICATION OF GIS SYSTEM SAFETY DO’S DON’TS CONCLUSION 4 20-21 21 21-22 22-23 22 23 23 23 23 24-25 25 25 26 26 27 27 28 29 29 29-53 53 53-54 54-55 55 INTRODUCTION ABOUT CORPORATION: BACKGROUND: In November 1986, the government had approved the implementation of 2400 mw Tehri hydro power complex, as the joint venture of government of India and state of Uttar Pradesh. THDC was set up a joint venture corporation of Govt. of U.P. in July 1988, and the work transferred to the corporation in Feb 1989.The financial participation of Govt. of India (GOI) & Govt. of U.P. (GOUP) in the implementation of the above complex was agreed to as 75:25 for power component, while the irrigation component was to be funded entirely by the GOUP. OBJECTIVES :Commissioning of the 2400 MW Tehri Hydro Power Complex comprising Tehri Dam & HPP (1000MW). Koteshwar Hydro Electric Project (400MW) and Tehri Pumped Storage Plant (PSP 1000MW) for benefits during the 10 th and 11th plans implementations of Vishnu Gad Pipalkoti Project (400MW) for benefits in 11th plan. 5 To accept corporate social responsibility (CSR) including rehabilitation & resettlement of project affected persons (PAP) with human face. To build sustainable and value based relationship with stake holders for mutual benefits and growth.VISION : A major global player in power sector. Create work ethos of growth through professionalism and achievement of excellence.5m high earth dam is constructed on river Bhagirathi in Tehri Garhwal district in Uttarakhand. To achieve performance excellence by inspiring a dedicated workforce in an environment of organizational learning and mutual trust. Most suitable type of dam (with central clay core) in earthquake zones on account of flexibility and capacity to absorb energy.36 T/cubic-meter to reduce settlement and build up of pore pressure during earthquakes. affordable and sustainable power with commitment to environment ecology and social values.5H: 1 V and 2H: 1V respectively. ensuring environment and ecological balance. To meet the challenges of dynamically transforming business environment and setting global benchmark.5 m wide crest is provided to safeguard the dam against the effects of magnification of earthquake acceleration at top of the dam. a 260. Compaction of shell material to a high density of 2. MISSION : To plan. DAM DESIGN FEATURES : Under the construction of Tehri hydro project.develop hydro as other energy resources from concept to commissioning and operate power stations to meet the growing energy demands. contributing to national prosperity. promote . 6 . A 25. providing quality. Tehri dam is high earth and rock-fill dam having upstream as well as downstream as 2. 511 sq.125m. km is snow bound. The dam body consists of 5 zones of materials namely: Central incensed clay core Upstream and downstream shell Coarse filters Fine filters Rip-rap over the slopes A layer of fine filters consisting of fine san is provided on the upstream of clay core.540 million cubic. The catchment area of the river at dam site is 7.meters at FRL of 830 m out of which 2.5m above FRL provided to prevent overflowing of the dam Length of dam at the crest is 585m and width at base 1. The total storage of the reservoir is 3. Despite constructed in highly seismic zone the constructional design of dam is such that it can withstand an earthquake of magnitude of 8. this material would get washed into cracks and seal them. 7 .5. Downstream filters are consisting of both coarse and fine have been provided to prevent migration of fine particles of core in the event of cracking. km out of which 2. The spread of Tehri dam reservoir is about 42 square km at gull reservoir level. In unlike event of cracking of core.615 million cubic –meters is live storage and 925 million cubic –meters is dead storage. Liberal free board 9. Top of dam is at elevation level (EL) of 839.5m with full reservoir level (FRL) at 830m and maximum water level (MWL) at 835m.323 sq. 1 in 10.340 cumecs.01% (i.000 cumecs ( cubic-meter /sec). It would involve a drop of 220m which has been negotiated by construction suitable energy dissipation arrangement of well designed stilling basin.the spillway system has been designed for a probable maximum flood (PMF) of 15.SPILLWAYS :Spillways are used to discharge excess water from the reservoir.000 years). The maximum velocity of flow would be about 55m/s. these are designed and constructed for making it possible that there is no harm to valuable structure of dam during extreme flood condition .e.the total discharging capacity of all spillways is 13. There are basically three types of spillways installed: 8 .540 cumecs. Probability of flood of this magnitude is considered as 0. The routed discharge corresponding to MWL of 835m through the spillway would be of order of 1. Aerators have been conferred to provide an aircushion under the water flowing over the concrete surface of chute so as to save the surface from cavitations damage.W=80m) placing such a large stilling basin on a wide shear zone is unique. The stilling basin (L=140m .a) CHUTE SPILLWAYS: The chute spillways have been provided to negotiate gross head of about 220m and the velocities generated are of the order of 55m/s at the end of glacis. It dissipates about 26% of energy. Baffle wall is provided for the dissipation of energy. SPECIFICATION (CHUTE SPILLWAY): 9 .the size of monolithic concrete block being placed in stilling basin is (L=60m.W=50m ) has been designed as monolithic concrete structure in the upside portion under which lies a shear zone . 5m : 578m : 3 : floor finish level. 10 . In the left bank shaft spillways the junction of vertical shaft with the horizontal tunnel. the air accompanied the flow in vertical shaft . this air core is pressurized air zone from where air is taken out to the atmosphere through de-aeration tunnel . is forced to be located in centre core by way of centrifugal force .Crest level Type Water way Size Length No of aerators Stilling basin Length of stilling basin Type of hoist radial Stop –log Design discharge : EL 815m : radial gated and stop –log : 3bays : 10. The right bank vertical shaft have been joined with existing diversion tunnel T-3 and T-4 eccentrically through a narrow section including swirling motion to the flow for energy dissipation in shaft to avoid extensive erosion damage from the waterfall .negotiating a head of 220m through vertical shaft spillways has been done for the first time for such a big head.5×15. EL596m : 218m : rope drum hoist : gantry crane : 5480 comics b) SHAFT SPILLWAYS: Apart from the chute spillways four vertical shaft spillways have been provided . of shafts Diameter of the shaft Height of shaft : EL830.2m : radial ungated and stop –log :2 : 12m : 225m : rope drum hoist : electric winch : 1900 comics each : EL815m : radial gated and stop –log :2 : 12m : 203m 11 .SPECIFICATIONS (SHAFT SPILLWAY): Right bank shaft spillway Crest level Type No of shafts Diameter of shaft Height of shaft Type of hoist radial Stop –log Design discharge Left bank shaft spillway Crest level Type No. draft tubes. controlling of 4 head race tunnels(HRT).the work designated as power house works include intake structure . FEATURES OF POWER HOUSE EXERTION: i) MACHINE HALL:- 12 .5 ×6m : 276m Type of hoist –radial / Emergency Design discharge : hydraulic hoist : for regulation 2. The power house is housing 250MW each and other appurtenant arrangement . tail race tunnels (TLT).penstock. POWER HOUSE The power house at Tehri project is an underground power house located on left bank. butterfly valve chamber . upper and lower expansion chambers. lightings etc. machine hall.Type of hoist – radial Stop –log Design discharge : rope drum hoist : electric winch : 1900 comics each INTERMEDIATE LEVEL OUTLET (ILO): ILO is at elevation of 700m and is 276m long joining T-3 shaft spillway through a tangential junction. SPECIFICATION: Crest level Type Size Length : EL 700m : radial gated and emergency : 4. bus duct galleries . The work of power house has been carried out through various ‘ADITS’ provided at different levels. Application of special coating of ‘polyurea’ is applied for abrasion resistance in ILO. The main function of ILO is that to regulate the water at the downstream when no unit is operational. There is also the Compressor system. This is done by use of required software on the computers which simplifies the job of controlling all the four turbines from a single place. turbine. ii) CONTROL ROOM (CCS) Every aspect of power house can be controlled from this room.It mainly house the four turbine units and the place where the power generation takes place There are also the Unit Controls Boards for each Turbine (unit). Main Inlet Valve among other things. Governor system. Power generated from each turbine unit is shown here and recorded on computers for future use. 13 . and distribution of power within the plant. It can electronically control the valves. Oil control system. iii) HEAD RACE TUNNEL (HRT): Two HRTs each of diameters 8. yet to be constructed in second stage of equal size as that of generating unit. HRTs 3 & 4 will be used for it. iv)Ventilation system:14 .75m diameter to feed 4 generating units.5m which is bifurcated into four steel line pressure shafts each of 5. HRTs 1 & 2 are used for it. Pumped storage plant (PSP). Water enters through the different penstocks to the different generating units. vertical & lower horizontal reach including upper & lower bend.5m 15 .8m Penstock assembly chamber :117m×13m×19.3m Thickness of pillars between chambers :19. Each penstock comprises upper horizontal.75m.Circulating of air inside the powerhouse is done through a ducting network and blowers/fans of different capacity and is kept in operations 24hours a day. The diameter of penstock is 5. vi) BUTTERFLY VALVE CHAMBER (BVC) Butterfly valve chamber :121m×10m×23. v) PENSTOCK ASSEMBLY CHAMBERS (PAC): There are 04 Numbers of penstocks attached with butterfly valve. 7m Upper expansion chamber :179m×11m×20m viii) VARIOUS TYPES OF EXCITATION SYSTEMS:There are two types of Excitation system.2m Transformer hall : 161m×18m×12m Thickness of pillar between transformer hall and machine hall :41. These are mainly classified as (i) Dynamic exciter (rotating type) (ii)Static exciter (static type). The different types of excitation being used are classified as Separately excited (DC) excitation system Self excited (DC) excitation system Brushless excitation system Static excitation system DIRECT CURRENT EXCITER 16 .vii) MAIN CARVEN: Machine hall:197m×23m×47. Then 15. AVR is the brain of excitation system and the power transformer used here is core type and is of higher power. 17 . Pulse transformer is use to smoothen the gate pulse. In power failure DG set supply DC 220V for initial Excitation before it 4 th unit SST will give supply to 1st unit. Heat sink are also present excitation system. The current from the rotor three-phase winding of the exciter is supplied to the main machine via rotary power converters. -THREE-PHASE AC EXCITER The exciter has a rigid connection to the shaft of the main machine.75KV is step down to 712V and then used for Excitation. -STATIC EXCITATION The excitation power from one transformer is supplied to the main machine via slip-rings by a controlled power converter 11KV supply comes from outside of power house for excitation of synchronous generator which is step down to 415V and for starting it is further step down to 30V to excite the generator poles. If the 4th unit is not working then DG sets are used. Isolators present in excitation system isolates the system in case spikes comes.The exciter has a rigid connection to the shaft of the main machine. When 30% of the rated power is achieved external supply is disconnected from generator poles. For excitation DC supply required so AC is converted into DC with the help of full bridge rectifier. The armature circuit is connected to the slip-ring of the main machine. ix) TAIL RACE TUNNELS (TRTs): There are 2 tail race tunnels each of diameter 9m and each carrying discharge from two units. Tunnels are of length 703m and 770m respectively. viii) FIRE FIGHTING SYSTEM :- 18 . TRT 1 discharges the water from units 1& 2 and TRT 2 discharges from units 3 & 4. generator guide bearing(UGB) for transformers cooling. vii) COOLING WATER SYSTEM:Water is taken from Draft tube/ Tail Race common cooling water header for stator winding cooling. Five pumps have been installed for this purpose. fire tanks are located at Adit 1 EL 706. It can also control the distribution of the power generated throughout the plant. the Voltage and Current among other variables.0m level) for pressure for the hydrant installed at strategic locations water for fire fighting. Braking of the turbine unit when required can also be done from the UCB. have been constructed for diversion of water during construction period. 2& 4. Internal hydro force. ix) UNIT CONTROL BOARD: It is needed to manually control the Turbine Unit when required. 3. Finally these are used as shaft spillways.0 penstock No. x) DIVERSION TUNNELS: There are four diversion tunnels each of 11m in diameter.TECHNICAL DATA OF GENERATOR In generating power station there are four generating units . It also shows the power being currently generated by the unit. It also consists of relay protection systems to protect the unit in case of any kind of failure. Two pumps are installed at Adit 1 (706. Temperature Reading from RTD (Resistance Temperature Detectors) is shown here.04 Nos.each of capacity of 250MW producing a total power of 1000MW at FRL. horse-shoe shaped. These hydro-generators connecting in generating station are servo-generators installed by the soviets in the 19 . The baffles are fastened in upper and lower parts of the rotor arm. The core is pressed by steel pole end plates with pressing studs. Pole cores are assembled of punched steel sheets of 2mm thick. stacked rim and 28 poles. each of them are of 12 feet in height. Thrust bearing hub and shaft. They provide cooling air inlet into rotor spider. BRAKING SYSTEM: 20 . The turn-to-turn insulation is done by glass tape with epoxy binding agent (F–class). Rotor rim is assembled of segments stamped of steel of 4mm thick and it should be tightly wedged on rotor spider.extension with shrunk upper guide bearing hub. at “Yekaterinburg” which is was a Russian – Ukrainian Company.year 1989 which are the production of “Uraelectrotiazchmach”. ROTOR: Rotor of hydro – generator consists of 14 arms fastened to rotor hub. The sheets have insulating coating in order to decrease the losses. spider. POLES: There are 28 poles in generator set. When the hydro.f.8 MPA pressure. SPECIFICATION OF THE GENERATOR: Name of machine : turboatom Type : CB870/300-28 No of poles : 28 Insulation : glass textolite (F class) Rated output : 278MVA/250. When rotational speed is reduced down to 5% of rated value.29rpm Runaway : anti-clockwise Voltage rise after 100% load rejection with p. (0.9) :28 v : 410rpm Direction of rotation Efficiency under rated load with p. the mechanical braking is automatically switched on when rotational speed is 40 rpm.f.2MW Maximum continuous output : 305.8MVA/275MW Power factor : 0. turbine wicket gates are closed and rotational speed is reduced to 50% of rated value.75 KV Rated current of stator : 10190.9) 21 : 98.9 Rated voltage : 15. With mechanical braking installed under rotor rim and operated by compressed air flow with 0.7 A Rated current of rotor under rated load : 1600 A Rotational speed – rated : 214. (0. the mechanical braking is automatically switched on.18% .generator is disconnected from the grid. In case of failure of electric braking or electric damage to generator. short circuiting of main terminals of stator winding and current supply into rotor winding from braking thyristor convertor occurs. There are 24 pneumatic brakes provided to end. The transformer hall under stage -1 has been constructed to accommodate the generator – transformer for PSP. In case of Tehri PSP. The surplus offpeak energy available in the grid is utilized to pump the water from the lower reservoir to upper reservoir for generation during peak hours. The PSP envisages 4 reversible units of 250 MW each. Annual generation from the project would be 1337MU . under which the reversible units shall operate.this perception is installed in only few hydro projects which can be boon at the time of energy crisis. major civil works to be taken up in PSP involve only the machine hall. An important feature of the project is the large variation of about 90m between the maximum and minimum head. the energy requirement will be of the order of 1712MU .for pumping operation of reversible units during off-peak hours. PUMP STORAGE PLANT (PSP) PROJECT FEATURE: Pumped storage plant is based on the concept of recycling of water between two available reservoir . interface facility for power evacuation have also been completed . intake for PSP have already been completed. The main cable galleries. STATUS: Essential work of Tehri PSP has completed along with the excitation of Tehri stage -1 works (the current generating unit). the Tehri dam reservoir shall function as the upper reservoir and Koteshwar reservoir as the lower reservoir (having an installed capacity of 400MW).thus.with the construction of Tehri PSP. TRTs. The project is scheduled for commissioning by June 2011. The HRTs.Maximum erection weight : 670T 4. COST: 22 . Tehri HPC shall function as a major peaking station having an installed capacity of 2400MW. penstocks and surge tanks. 64 crores at December. Tehri PSP is one of the lowest capital cost of Rs. TARRIF: The beneficiary states should provide off peak from there allocation from there pumping operation of Tehri PSP as banking transaction. The corresponding peaking power would be returned to the beneficiaries after adjusting pumping losses. durability and reliability. both during peak and off peak hours. The govt. of India has approved the execution of Tehri PSP in July . 2006 at a cost of Rs .7 crores/MW of installed capacity. 5. Further with the settling up of Tehri PSP. full peaking power benefits from the 2400MW Tehri complex would be available. The project shall also provide the balancing load to the base load thermal power plants during off-peak hours. (anticipated peak shortage in the northern region at the end of XI plan is estimated as 12.049 MU). thereby reducing severe operating condition of thermal units and improving their efficiency. transmission losses etc. 1.Haryana (100MW). Uttarakhand (200MW). 23 . The charges being paid by the beneficiaries will reduce enormously. as was envisaged at the time the THDCIL as conceived. The project will avail the natural advantage of two reservoirs created by Tehri Dam (stage -1 ) and Koteshwar dam. and recovering the fixed charges of the Tehri PSP in the proportion to the pumping energy supplied by them.ADVANTAGE OF TEHRI PSP: The 1000MW PSP project is one of the few sites suitable in northern region suitable for PSP. The Tehri PSP shall contribute the meet the peak demand. The PSP will render a great help to maintain the grid frequency profile in the grid. 1657.30 paisa per KWH at constant cost. 2005 (with debt equity ratio of 70:30). and Rajasthan (100mw) totaling 1000MW.60 crores including IDC of RS 81. The conversion cost works out to be 189.984 MW while energy deficit as 68. power purchase agreements for supply of off-peak and purchase of peak power have been tied up with beneficiary states–Delhi (600MW). 6. etc. The control circuit should be neatly dressed with proper identification clear marks. As per studies Tehri PSP is an attractive project from economic point of view. 4 years. Desired purity level of hydraulic oil is required to be maintained to give trouble free operations. should be carried out. Periodic al maintenance of governor along with all associated mechanical.e. electrical and electronic components is to be carried out. Considerable civil works have already been completed under essential works executed along with Tehri stage -1.ELECTROMECHANICAL EQUIPMENT MAINTENANCE: TURBINE AND ITS AUXILLARIES: The Francis turbine is always immersed in water but its inspection should be done as recommendation by manufacturer without any compromise. meters.The project can be commissioned within relatively short period i. The electronic components and cards should be carefully maintained at appropriate temperature level to achieve desired performance. Periodical calibration and testing of transducers. Following activities broadly covers the maintenance activities to be done in turbine & governor: 24 . The location of PSP parallel to the Tehri HPP will share a number of common facilities created as part of Tehri stage -1. Due to cavitations there may be huge damage to runner causing adverse effect on performance and efficiency. 7. Internal runner housing painting with anti – corrosive / tar based paints. slot wedges are checked for healthiness. Looseness of stator core or inter lamination. Ultrasonic. Polishing of turbine once in a year to minimize the white pitting. Inspection of labyrinth seals in case of reaction turbines. GOVERNOR: Purification of hydraulic oils by centrifugal as well as electrostatic liquid. core insulation are factors directly affecting wining heating due to eddy current loss.End spacers . etc. Periodic maintenance of the servo valves and motors.inspection of the stator winding to verify it’s firmness in stator core slots and healthiness overhang portion with firm end winding caps . Inspection of the testing of the runners from experts to decide residual life so as initiate procurement of runner for replacement. if necessary. GENERATOR AND ITS AUXILIARIES: Likewise impedance test (voltage drop test across each pole) indicates condition of rotor winding. Applying anti – erosive coating to the runner. Windings are varnished to enhance its life.Turbine: Periodic NDT viz. Thus recommended maintenance as per schedule is done and its records are maintained and corrective action is taken. 25 . Inspection of the pistons and housing of the servo valves and motors to check for worn – out. proper cooling system is maintained to limit rise in stator winding temperature and consequently increase the life of stator winding . temperature rise etc. 26 . coupling misalignment. Fire fighting system. Periodic oil filtration. etc. Operating and testing of isolators opening and closing of Control circuit checking and healthiness of operating system of the breaker. maintenance and inspection. Periodic checking of the foundations and tightening of the bolts. mock trials. unbalanced electrical components. Inspection of CTs and PTs. History of the recorded readings gives guideline for realignment. bus bars for overheating. Inspection of protection controls circuits and mock trials of the fire fighting system along with evacuation system. Periodic cleaning or replacement of the generator air coolers and bearing coolers to improve performance of the generator. TRANSFORMERS AND SWITCHYARD: Following works are required to be carried out foe proper up keeping transformer and switchyard: Continuous monitoring of oil and winding temperature. looseness if any. Oil testing for various tests and dissolved gas analysis. increase in bearing gaps. CO2 and emulsion checking. Filling the foundations with epoxy. Primary and secondary testing of the protection system for its healthiness and correct operation. 8. Breaker time test. uneven stator – rotor air gap. Checking the vibration periodically. Checking of the CO2 cylinders and replenish as per recommendations of OEM. Oil cooling cleaning and replacement. Tan delta and megger test as per schedule. The process of restoring the power system is commonly referred to as black start. The purpose of this article is primarily to provide prospective generators with an insight into the technical and commercial consideration association with the black start service. 27 . All large power systems require some contingency arrangement to restart in the unlikely event that all or a part of system shut down. This entails “isolated” power station being started individually and gradually being reconnected to each other in order to form an interconnected system again . Hence a black start is a process of restoring a power system to operation without relying external energy sources.BLACK START OPERATION :SYNOPSIS: The Tehri HPP is one of the few plants in the country to have black start capability.9.not all power stations have or are required to have the black start capability. The DC generator is used to run generating unit and excite the station service transformer (SST) which is used to provide the DC excitation to the generator after passing through the direct voltage regulator (DVR) and automatic voltage regulator (AVR). TECHNICAL REQUIREMENTS: Irrespective of the type of plant to provide black start service. the following technical capabilities is required: The ability to starting the main generating plant (at least one unit / module) from shut down is agreed time scales without the use external power supplies from the transmission distribution system. there is DC diesel generator which is used for the black start operation. The capability to energies part of the grid within shortest possible time. The reactive capability to change the immediate transmission distribution system. Here in the Tehri HPP. The capability to accept instantaneous loading of demand blocks and controlling. Key transmission lines between the hydro station and other areas are energized. The power from the diesel generator is used to bring the hydroelectric generating station into operation. 28 . BLACK START SEQUENCE: A typical sequence (based on real scenario) might as follows: A battery start a small diesel generator installed in a hydroelectric generating station. The capability will depend upon local system configuration but generating plant connected at 400kv or 132 kV with a capability of at least 100MV leading (as measured at commercial interface) should almost invariably match this requirement. Frequency and voltage levels waiting accessible limits during the block loading process (under these conditions frequency will be within the range of 47 to 52 Hz). Also with this arrangement. wind turbine are usually connected to induction generators which are in capable of providing power to a de-energized network. 420 kV Gas Insulated Switchgear and associated equipment located indoor is designated as GIS-I and GIS-II. DISTRIBUTION SYSTEM:TECHNICAL SPECIFICATIONS OF GIS SYSTEM The underground 420 kV SF6 Gas Insulated Switchgears (GIS) & Gas Insulated Bus ducts (GIB) were selected mainly in Tehri HPP stage-I due to non availability of space for open switch yard. The power from the hydro dam is used to start one of the coal.fired base load plants. Many large high – voltage direct current convertor stations cannot operate into a “dead “system. 10.630.5) 420KV GIS system designated as GIS-I. Generator Transformers & Switchgears. and efficient & reliable service conditions ensuring reliable energy supply. The power from the base load plant is used to restart all of the other power plants in the system including the nuclear power plants. Potential Transformers.618. consist of Circuit Breakers. function and operation of the Electro-Mechanical Equipment comprising of Generators. the same may be true of mini – hydro or micro – hydro plants . Grounding 29 . which also rely on a power network connection for frequency regulation and reactive power supply . very low operating cost. for example . safe operation. either since they require communication power from the system at the load end.0) and at other end with GIS-II at the end of bus duct tunnel at interface facility area (at EL. Two circuits of Gas Insulated Bus Ducts (GIB) have been laid in 800m long tunnel which is connected with GIS-I at one end at GIS hall (at EL. compact layout of the underground power station. Current Transformers. LIMITATIONS OF BLACK START OPERATION: Not all generating plants are suitable for black start capability. and Overhead power lines are arranged optimally. Disconnecting Switches. The induced voltages on the enclosures are with in reasonable limits of safety for operating personnel. Grounding Switches.Switches. located indoor near pothead/interface. The equipment and part of it are strong enough and sufficiently well connected to resist total operating stresses resulting from the forces in normal operation and in abnormal condition with forces superimposed due to occurrence of earthquake. Disconnecting Switches. supporting steel structures and all other equipment. They are equipped with SF6 Gas servicing & monitoring arrangement complete with non-return valve connectors for evacuating and filling the gas.1. over-pressure relief device. A horizontal seismic coefficient ah=0. gas density/pressure monitoring devices with necessary contacts for alarm/trip interlock & auxiliary contacts and terminals for event recording .0 on Richter scale or Intensity IX on modified Mercalli Intensity scale (MM scale). 30 . GIS equipment installed in GIS hall at EL 618m is shown in fig. Lightning Arrestors. comprises of Current Transformers. Control panels. The Tehri dam and other structures have been designed for a probable earthquake of magnitude measuring 8. Transition Bus. Enclosures of each gas compartment are fitted with gaskets / O-ring seals to provide an effective gastight joint between equipment & Bus duct sections.0 The second 420 KV GIS system designated as GIS-II. Each gas filled compartment is equipped with static filters capable of absorbing water vapor which may penetrate into the enclosures.15 and a vertical seismic coefficient av=0.075 are considered for calculations of seismic forces acting on the equipment during earthquakes. Transition Bus Section between GIS and OilSF6 bushings of Generator Transformers. and SF6/Air Bushings for the 400 kV outgoing feeders. No. 3. Description Maximum (continuous) service rated voltage. IEC-56 and has the following performance characteristics and ratings: S. KV Rated normal current (Amp) i) In bays (except bus-coupler) ii) In bus bar bus-coupler bay Braking capacity i) Rated Braking current ii) MVA(symmetrical) Rated Short Circuit making current Rated Short Circuit make time 31 Rating 420 2000A 4000A 50KA 36. 2. 1. 1. 4.Fig. 5.37X103 MVA 125 kA 84 m sec .0 GIS EQUIPMENT INSTALLED IN GIS HALL AT EL 618M. CIRCUIT DIAGRAM See the fig 2. Equipment of 420kV switchgear is presented by GIS. 10.0 Single line diagram (SLD) of GIS.73 514 7 120 17 ≤5pC at 1. 18. mm² at 20°C i) 1425 1665 2. bus ducts and GIS-II at the Interface facility. Rated lightning impulse withstand voltage (kV peak) i) ii) 7. 9. comprising GIS-I in the power house. 8.62X10ˉ6 Bus conductor 5500 ii) Bus enclosure Conductivity of material in A. 1050 520 610 40 pF/m 86 7. BB22 32 .1Un/√3 2. Rated Switching impulse withstand voltage (kV peak) Rated 1 minute power frequency with stand voltage (kV rms) i) To earth ii) Across open switching device Capacitance per meter of the enclosed single phase bus bar Surge impedance of enclosed single phase bus bar in ohms Electric Resistance at 75°C in ohm/m i) 12. 16. To earth Across open switching devices Bus conductor 11225 25 ii) Bus enclosure Current Density in Bus conductor in A/ mm² Bus enclosure outside Diameter in mm Bus enclosure wall thickness in mm Internal Bus outside Diameter in mm Internal Bus thickness in mm Partial discharge level 24 0.8 X 10ˉ6 Bus enclosure ii) Internal bus Cross sectional area in mm² i) 13. m /V. 14. The double bus scheme with bus coupler is adopted for the 1st stage of the Tehri Dam Project – 1st bus system with BB11 and BB12 sections and 2nd bus system with BB21.6. 15. 17. GIB and outdoor switchyard equipment. 11. 19. ACA05-Q21). In normal operation. Fig. 33 . The bus coupler circuit is so completed with normally closed disconnect switch (ASA04-Q11 and …Q21 or …Q21 and …Q12) that on closing of the circuit breaker it integrates sections BB11 and BB22 or B21 and B12.0.sections. the sections of each bus systems are combined by closed disconnect switches (ACA05-Q11.2. Bus coupler =ACA04-Q0 is normally closed. The generator transformers and lines are connected through one circuit breaker and bifurcations of two disconnect switches. Voltage transformers and ground switches are installed on each section of GISI buses. and surge arrestors are installed on 306 MVA transformer bushings and outgoing lines. The generator transformers are fitted with oil/SF6 bushings for connection to the 420 kV GIS via bus duct stretches. SINGLE LINE DIAGRAM OF GIS & GIB SYSTEM The 420 kV transmission connections are carried from line GIS bays =ACA01 and =ACA02 by the SF6 bus ducts GIB laid in a 670 m long horizontal bus duct tunnel. - Voltage transformers. SF6 monitoring instruments. b) - Bus bars. GISII. - Connection bays. and SF6 equipment. interlocking and remote control circuits. GIB. - Circuit breakers. - Line disconnectors. current. It presents sharing of active and reactive power. These cubicles house also equipment for signaling. voltage transformers ground switches. - Bus disconnecting switches. - Grounding switches. c) The operator station in the central control room displays control of GIS. lines. capacitive voltage transformers and surge arrestors of outdoor installation are installed on lines of the IF. 3. voltage and frequency of the buses and 34 . Line traps.At the Interface Facility site the bus ducts via disconnectors are connected to overhead lines W1 and W2 from the Meerut substation. - Current transformers. GIB and overhead line bays in file 420 kV GIS1. local control switches for disconnector is located in the pole control cubicles.Connection modules of transformers. - High speed make proof grounding switches. LIST OF MAJOR EQUIPMENTS OF GIS: a) Standard elements: . as well as local controls of C/B operating mechanisms. - Surge arrestors. as well as the current passing through the bus coupler. It is designed to break small inductive currents without causing excessive over-voltages.3. Provision is made for simultaneous opening and closing of all the three poles of the circuit breakers for generating units and bus coupler and also capable of interrupting symmetrical short circuit current under out-of-phase switching conditions. temperature rise above ambient at rated load & voltage i) 2000A 125 KA 50 KA(rms) 610 kV (rms) 65°C Contacts 65°C 35 . radio interference and corona. i) 2. 1. The SF6 gas-insulated Circuit Breaker as shown in Fig. uses SF6 gas for both insulation and arc quenching. In-rush and magnetizing current associated with large power transformers (three Phase 306 MVA Generator Transformers) are switched by the circuit breakers without re-striking & causing excessive switching surges. 4. Rating to Earth 520 kV (rms) ii) across open contacts Max. These circuit breakers are provided with independent and reliable operating mechanism for each pole. 3 conforms to IEC-56 and has the following performance characteristics and ratings: S. The mimic diagram shows position of the switching devices and status of connections. Bus coupler breaker 4000A ii) Generator and line breaker Rated Short circuit making current Rated short circuit breaking current 1 minute power frequency withstand voltage i) 5.No. A) CIRCUIT BREAKERS:The three phase circuit breakers are of self-blast type having two interrupting chambers per phase. Pictorial view of Circuit Breaker is shown in fig. Description Rated normal current. line charging currents without re-strikes handle evolving faults and meet the requirements regarding partial discharge.outgoing lines. 3. 5 ltr.6.3 s-CO-3 min- Generator-Transformer and Bus coupler breakers CO 0-0. 7. is required. remake for auto re-closing. 253 ± 3 bar at 20°C iv) Quantity of oil required for one close open 2. Number of mechanical operations. phases.1 ltr. Maximum difference of time at opening between < 4 ms 11.5 bar at 20°C v) Compression ratio for puffer action vi) Quantity of Compressed gas for puffer action 36 1.1kW. Maximum difference of time at closing between < 5 ms 12.5 bar at 20°C ii) Normal operating density 49.3 s-CO-3 min- 8. Current. . 3000 Amp. Maximum time from arc extinction to contact CO 300 ms 9. with maximum 6000 Nos.8 7. Maximum difference of time at opening of series < 2 ms 10. 3ph. ii) Hottest part Rated operating duty cycle Line breaker 0-0. operation SF6 Gas System i) Normal operating pressure 6. Hydraulic fluid supply for mechanical operation i) Pump / Motor 1.5 kg / m³ iii) Weight of gas per breaker 345 kg iv) Lock out pressure 5. 14. phases. ii) Storage compartment pressure 253bar to 345 bar at iii) Minimum oil pressure required for successful 20°C interruption. 415V. contacts within one pole. before scheduled maintenance 13. Dry 1 min. breaker at operating pressure 15. The Disconnectors conform to IEC-129 and have the following ratings: S. 1. Rated Lightning impulse withstands voltage 1665 kVp between terminals with disconnecting switch in 3. Rated Description switching impulse withstands voltage Rating 1245 kVp between terminals with disconnecting switch in 2. open position. The Disconnectors are electric motor operated and also equipped with a manual operating mechanism for emergency use. Contact shielding has been provided to prevent re-strikes and high local stresses caused during interruption of Transient Recovery Voltages.9 dB i) ON operation 106.vii) Total volume of SF6 gas required per circuit 6900 ltr. open position.No. single-pole and group operated type are provided for electrical isolation of the circuit breakers from the Transformer. power frequency withstands voltage between terminals with disconnecting switch in open position 37 610 kVp . viii) Average leakage of gas per year Noise level of circuit breaker operation at 8 m ≤1% distance 106.3 Db ii) OFF operation A)DISCONNECTORS:Disconnectors of 3-phase. Disconnectors are guarded against the effect of VFT (Very Fast Transient). Double Bus and Transmission Lines. 6. These grounding switches are capable of interrupting the inductive currents and withstand the associated Transient Recovery Voltage. 7. located in Generator-Transformer bay and at the entrances of the transmission lines. These switches are electrically interlocked with their associated circuit breakers 38 . or remotely from the power house control room in conjunction with opening of the associated Disconnector. group operated work in progress safety grounding switches are provided as shown in SLD. High speed make proof Grounding switches. The short circuit making current rating of each grounding switch is 50 KA. A) SAFETY GROUNDING SWITCHES & HIGH SPEED MAKE PROOF GROUNDING SWITCHES Three-pole. Opening 4s ii) Closing 4s Rated capacitive breaking current 0. Partial discharge level ≤5 pC at 1.7 Amps.4. Operating time of isolator along with its operating mechanism i) 5. of operations the switch can withstand without 3000 nos. The safety grounding switches conform to the requirements. The short circuit making current rating of each grounding switch is of 125 KA. Each safety grounding switch is electrically interlocked with its associated Disconnector and circuit breaker so that it can only be closed if both the circuit breaker and Disconnector are open.1Un/√3 No. any need for inspection. High-speed ground switches are either operated locally from the bay module control cabinet. in addition to their safety grounding function. are used to discharge the charging currents. The switches conform & have inducted current switching capability as per IEC-129. 39 . The secondary windings are air insulated and mounted inside metal enclosure. The Current transformers are provided with the transformation ratio of: 500/1 A to 4000/1 A. The current transformers are provided in all the incoming bays. The secondary windings of these CT’s are connected to protection and measurement circuits. All current transformers have effective electromagnetic shields to protect against high frequency transients. The current transformers are periodically cleaned from outside to avoid dust layer formation.such that the grounding switches can not be closed if the circuit breakers are closed. B) CURRENT TRANSFORMERS The current transformers incorporated into the GIS are used for protective relaying and metering and are of metal-enclosed type. 40 . Primary terminals 4.1. Secondary box terminal 7. Insulator 6. Protective cap 2. 420KV CURRENT TRANSFORMER 41 .7. Active part 5. Oil drain valve FIG. Below 3. The air terminations consist of a porcelain shell which encloses the conductor & ground sleeve.11kV.The voltage transformers have three secondary windings & conform to IEC-186.000 Amps 42 . 420/3:0. 1.11/3kV. The bushings are of condenser type with grading elements & are fitted with capacitance taps for the measurement of tan delta and partial discharge.11:3kV. and used for protection. 420/ 3:0. S. metering and synchronizing. Description Rating Rated current 2. The voltage transformers are provided with the transformation ratio of: 420/3:0. C) SF6 -TO-AIR BUSHINGS The 400KV overhead lines are connected to SF6 GIS (GIS-II) by Air / SF6 gas filled bushings. The spaces surrounded by the porcelain insulator are filled with SF6 gas slightly above atmospheric pressure. These are of induction type non-resistant and effectively shielded against high frequency electromagnetic transients. The shells are sealed to aluminum flanges by Elastomer seals. In case the porcelain is damaged. this shall keep consequences down to a minimum. The conductors are provided with a plug in contact to accommodate thermal expansion and facilitate replacement of the bushing shell without disturbing welded line sections.B) VOLTAGE TRANSFORMERS The voltage transformers are located in a separate bay module on the bus and are connected phase-to-ground. No. The Air/SF6 bushings which are complete with suitable corona rings conform to IEC-137. The bushings divide into independent gas compartments by a barrier insulator with grading electrodes. heavy duty. Access openings are provided in each phase terminal enclosures to permit removal of connectors to isolate the step-up transformer. External Phase to Ground strike distance 630KV (rms) 3540 C) INTERFACE BETWEEN OIL-TO .2.SF6 BUSHINGS AND GIS The interface section from Oil-to. Maximum continuous voltage 276 43 . Description Rating 1. The connection at transformer bushings allow at least 25mm of movement in any direction. No. Rated voltage of arrestor KV(rms) 345 2. 3. side of Generator Transformer and the Bus / first Disconnector of the GIS – I. Rated Switching impulse withstand voltage 1050KV(peak) 5.V. metal enclosed surge arrestors are gapless metal oxide. Each arrestor conforms for Gapless Arrester and has the following technical performance characteristics and ratings: S. D) SURGE ARRESTORS OF GIS-I SF6 gas insulated.e. Corona extinction voltage ≥550 KV (rms) 8. Temperature rise As per IEC-137 7. Rated short time current (rms) 50 KA for 1 sec. Rated Lightning impulse withstand voltage 1550KV(rms) 4.SF6 Bushings of the Generator Transformers to the GIS system is a part of GIS i. One minute power frequency withstand voltage 6. station type and are located on H. the enclosure of SF6 equipment and the HV bushing of the transformer as per IEC 1639. 1300 GIS component. The chambers of three phases are interconnected by pipes and form a common gas compartment. Maximum switching surge protective voltage at 666 1kA for 30/60 micro second wave kV (Peak) 5. kV(peak) 7. 44 . 6. kV(peak) Switching surge 1425 withstand voltage of 1050 equipment to be protected. kV (peak). Maximum discharge current 20 (8/20 microsecond wave) Ka 4. Lightning Impulse withstand voltage of equipment to be protected: . kV (peak). Residual voltage at 10 kA (8/20 µs current 793 wave). (L-N). kV rms 3.Transformers.capability. A continuous gas compartment can be subdivided by gastight bushings. 8. Energy level kJ/kV 10 E) BUSBAR MODULES Single phase enclosure for each bus bar. installed in a naturally ventilated tunnel. 4) GAS INSULATED BUS DUCTS (GIB) Two circuits of Gas Insulated Bus Ducts. The bus system consists of two concentric aluminum alloy tubes. in which conductor & enclosure are supported by track resistance epoxy insulators. Conductor sections are joined together using silver plated plug-in contact finger assemblies. The space between the conductor and enclosure are filled with SF6 gas. are connecting the 420 kV GIS-I located at EL 618 m in the floor above transformer Hall and GIS-II located near the tunnel exit to the outside pothead yard.Busbar modules of adjoining bays are coupled together by expansion joints which take up design tolerances and thermal expansion at right angles to and along the bus run. Each phase of the GIB is subdivided into gas tight compartments capable of withstanding the specified seismic forces. Module conductors are linked by coupling contacts or flexible connectors which take up the horizontal thermal expansion. Faults are confined to the originating 45 . The spring loaded contacts allow the tubular conductor to expand or contract axially due to temperature variation without imposing any mechanical stress on supporting insulators. No. Description Rating 1.1 Un/√3 5. Short circuit current withstand capacity. Rated Switching impulse withstand voltage. 420 kV INTERFACE EQUIPMENTS A) CAPACITIVE VOLTAGE TRANSFORMER (CVT) The oil filled capacitive voltage transformers with porcelain bushing / insulators for outdoor service have been installed for metering. Rated Lightning impulse withstand voltage 1425kV(peak) 4. The conductor has multiple individually spring loaded silver plated finger contacts on one end forming a socket and mating silver plated plug on the other end. Limits of temperature rise for Conductor and As per IEC 694 enclosures. 7. 1050kV(peak) 5. Rated One minute power frequency withstand 520kV(rms) voltage. protection and coupling the carrier equipment to the 420 kV Tehri Meerut lines. 6. continuous current. The following are ratings of Gas Insulated Bus Duct assembly: S.compartments only and do not spread to the other compartments / zones of GIB. Partial discharge level ≤5 pC at 1. Max. (rms) 50KA for 1 Sec 3. The capacitive voltage 46 . A(rms) 2000 2. 7. tuning reactor / RF choke due to short circuit in the transformer secondary’s. Earthing link with fastener is provided for HF terminal. intermediate transformer and protective & damping devices. 40 to 500 KHz. A protective surge arrester is provided to prevent breakdown of insulation by incoming surges and to limit abnormal rise of terminal voltage of shunt capacitor / primary winding. CVT’s have been used for high frequency (HF) coupling of power line carrier communication. The damping devices are permanently connected to one of the secondary windings for suppressing the Ferro-resonance oscillations.e. The electromagnetic unit comprising compensating reactor. The following are ratings of capacitive voltage transformers: 47 . Carrier signal are prevented from flowing into potential transformer (EMU) circuit by means of a RF chock/reactor suitable for effectively blocking the career signals over the entire carrier frequency range i. Fig.transformers are single phase unit consisting of coupling capacitive dividers and electromagnetic units. having separate terminal box with all the secondary terminals. Basic Circuit diagram of CVT. HF terminal of the CVT are brought out through a bushing for connection to the coupling filters of the carrier communication equipment. No. radio interference voltage at 266 KV 7. One minute Power frequency withstand 2 KV (rms) voltage for secondary winding 12 Total simultaneous burden 13 No. Self tuning frequency of CVT MHz 10. Natural frequency of coupling KHz 9. of secondary’s 300 VA 3 48 . Max. 4. Rated insulation levels - Rating 1 Full wave impulse withstand voltage (1. 11. Description 1.Switching impulse withstand 1425 kV(peak) 1050 kVp voltage (250/2500 µs) between line terminal and ground 3. of poles 2. (rms) Partial discharge 8.2/50 µs) between line terminal and ground .S. One minute power frequency test voltage of 630 kV (rms) HF terminals. No. Stray capacitance and stray conductance of the 1000 Micro volts < 5 pc at 1. Corona Extinction Voltage (min) 320 kV (rms) 5.1 Un/√3 ≥ 100 ≤1 As per IEC 358 LV terminal over entire carrier frequency range. Its main coil carries continuously the rated current without exceeding the limit of 49 . a tuning device and a protective device are installed on the transmission line in R & B phases of 420 kV Tehri Meerut lines. Fig 4 . to prevent undue loss of carrier signal.14 Capacitance i) of high voltage capacitor 4400 PF+10%. Its impedance is negligible at power frequency (50 Hz) so as not to disturb power transmission but is relatively high over the frequency band appropriate to carrier transmission. -5% ii) for carrier frequency coupling 4571 PF Pictorial View of 420 kV Interface Equipments is shown in fig.4.420 kV INTERFACE EQUIPMENTS A) LINE TRAP :Line traps consisting of a main coil in the form of inductor. Min. S. It is tuned for its entire carrier frequency range.temperature rise and is supplemented with a protective & tuning device. Line surge Arresters are capable of discharging energy equivalent to class 3 of IEC for a 420kV system on two successive operations followed immediately by 50 Hz energisation with a sequential voltage profile of 705 kVp for 3 peaks. 580 kVp for 0. Type of tuning Broad Band 4. 565 kVp for 1 second & 550 kVp for 10 seconds. Resistive component of impedance of the line trap within its carrier frequency blocking range is ≥450 ohms. They are of heavy duty station class and gapless type without any series or shunt gaps and discharge over-voltages occurring during switching of unloaded transformers and Transmission lines.5/1.1 Sec. Corona rings are incorporated in the line trap. The line trap shows no visual corona discharge at 320 KV rms power frequency voltages. 3. 5. No Description Rating 1. Rated inductance of main coil 0.0 m H B) LINE SURGE ARRESTERS The surge arresters are hermetically sealed units and are connected to the 420 kV Tehri Meerut line. Rated short time current for 1 sec. Nominal discharge current of protective device at 20 KA 8/20 µs wave. 50 . resistive component of impedance within 450 ohm the rated blocking band-width. Line trap conforms to IEC 353 (latest) & have following technical particulars. 50 KA 2.2/0. Max. Switching surge residual voltage at 1kA kV (Peak) 675 5. kV 7. S. continuous voltage capability. Switching surge withstand voltage of equipment to be 1050 protected. Application of impulse or switching surge voltages does not cause any external flashover on Porcelain housing. Max. Nominal discharge current (8/20. No. kV(peak) 8. Rated voltage of arrester KV(rms) 345 2. (L-N).2/50 µs wave. The surge arresters conform to IEC-99-4 & have following technical characteristics and ratings. Total creepage distance of arrestor housing mm 6. Equivalent front-of wave protection level (discharge 878 voltage with 1/2 µs. KV (peak). 51 10 . i) Max.The Surge Arresters are fitted with pressure relief devices for preventing shattering of porcelain housing and providing path for flow of rated fault currents in the event of arrester failure. Discharge counters. Switching surge residual voltage at 1kA kV (Peak) 696 ii) Min. Description Ratin g 1. µ sec wave) kA 20 4. without any requirement of auxiliary or battery supply for operation. 9. Impulse withstand voltage of equipment of arrestor housing 11030 1425 with 1. kV rms 276 3. are provided for each single pole unit along with necessary connection. Minimum discharge capability (KJ/KV) referred to rated voltage at minimum of discharge characteristics. 10 kA impulse current). Never start work on any pipeline or electric line till a permit has been issued . Operation wing isolate the faulty equipment and places proper tags so that the maintenance personal are not exposed to any hazard. etc. Carry all the required tools for the job in a bag and after completion do not leave any tool lying around. so that others cannot reach up to the hazard. Always wear head protection while going for maintenance Jobs. it must be replaced back after completion of work.. 1 minute power frequency (dry) withstand voltage of 550 arrestor (kV rms) 11. DO’S : If any floor cover or pit covers are removed for repair to machinery. place some barrier etc. i) At 50% nominal discharge current at 10 kA (kVp) ii) At 100% nominal discharge current at 20 kA (kVp) iii) At 200% nominal discharge current at 40 kA (kVp) 828 919 1018 11. 12. in service or available are under the custody of operational group. line has been isolate and tag has been placed at control switch showing that is under permit “NOT TO BE OPERATED “ . Max. SAFETY:The persons authorized for repair work must be aware with the type and hazards in a particular section and take required personal protective equipment. Maintenance wing should make request to the operation wing for permission work on any equipment. valve.10. 52 . It must be ensured that: All equipment. pipeline. Residual voltage for 8/20 µs current wave. He must observe the following guidelines while taking up a particular maintenance actively. When the work is in progress. Carry out all the electrical works after switching off the electrical supply. Provide proper earthing for the installation and motor casings. Please provide proper size of wiring for machinery to avoid voltage drop and insulation melting. Main switch board and meter should be safe and protected from dust. buzzing sound from electrical appliances are sign of potential hazards. replace broken switches / fittings immediately. Avoid joints in the wiring. main switch control box. sparks. Electric supply should not be given from one distribution board to another. Do not touch broken wires. Never consider a job completed till you have fitted their require guard. Always keep the fuse box. 13. etc. Don’t touch switches plugs with wet hands. insulation resistance should be measured with the help of megger and reported in the test report. contact qualified electrician immediately. Don’t go near to any place where ‘DANGER’ caution board is placed. Change immediately old and damaged wiring where insulation has been damaged. In case of fire from electrical circuits. Dim or flickering lights. DON’TS : Never start machinery or equipment without proper guard. Don’t use broken fittings. All switches should be connected to circuit phase wire. 53 . After completing electric wiring. Don’t tamper with electric meter. panel. Strictly adhere to all electrical rules and regulations. properly locked and without obstacles. Loose wiring results in sparking. switch off the electrical supply immediately and use sand carbon dioxide or dry powder extinguishers. Do not use water. Ensure that wires are tightened at both ends. Use armored cable for motor winding. All the necessary joints should have proper taps / insulation. Do wear rubber soled shoes when operating power tools. We got acquainted with each and every department engaged here and came to know about their working. heater and electric iron. running and maintaining the reputation of its extistence. CONCLUSION :Tehri HPP is unique in many aspects –Highest Earth and Rock fill Dam in Asia. Don’t insert more than one plug in socket. Don’t overload outlets. Don’t use older extension cords without inspecting them first. pull the plug top not plug wire. 13. Highest Shaft Spillways and many others. Don’t touch a bare wire. Don’t use any appliance. Don’t mix water and electricity. By virtue of this training programme we came to know about various technical aspects and implications of a hydro project and the hardwork and expertise of the officials and workers which they put in to make this massive project sustained. cooler without proper earthing. Don’t provide fuse on neutral circuit. 54 . Don’t make any temporary joints in the wiring without proper insulation. Don’t ignore switches outlets that don’t work. Largest Machine Hall Cavity. Don’t use electrical appliances or talk on the phone during an electric shock. The Four Week Training Programme at Tehri HPP was a great experience for me in particular and every individual that was there . While removing pin from plug socket. 55 .