Equipment: Retrofitting Thrust Bearings

FPL Energy experienced multiple failures of the thrust bearing in the single turbine-generating unit at its 6-MW Cataract plant in Maine. To solve the problem, FPL Energy installed a new eight-pad, spring-supported PTFE thrust bearing and a new thrust block. The retrofitted unit began operating in July 2006 and has been failure-free ever since.

By Paul J. Plante, Eric D. Soule, and Mike A. Dupuis
FPL Energy’s 6.65-MW Cataract project is a run-of-the-river hydro facility on the Saco River in Maine. The station has a single Kaplan turbine-generating unit that began operating in 1939. Between 1959 and 2005, the unit’s thrust bearing failed eight times, with half of the failures occurring between 2003 and 2005.
To deal with the situation, FPL Energy installed a low-profile, eight-pad, spring-supported thrust bearing and a new thrust block. This modification solved the problem – the unit has operated since July 2006 with no thrust bearing failures.

Problem with the thrust bearing
The spring-bed babbitt thrust bearing at Cataract is above the rotor in the upper bridge, which also houses the upper guide bearing. There is a lower guide bearing under the generator rotor and a water-lubricated turbine bearing in the head cover. In 1959, FPL Energy repaired the thrust bearing because it had suffered from eccentric wear over the initial 20-year operating period. The eccentric wear was believed to be associated with concrete growth at the station. The repair work included installing a sleeve on the thrust block. Since that repair, the thrust bearing failed eight times, with four of those failures occurring since 2003.

In 2004, FPL Energy took the unit out of service to repair an oil leak in the Kaplan head. When the unit was disassembled, personnel discovered two significant adverse conditions. First, the babbitt shoes on the thrust bearing were cracked. Second, misalignment of the powerhouse as a result of alkali-aggregate reactivity (AAR) had progressed to such a degree that the unit centerline needed to be reestablished. Work to correct these two problems took about ten months.

In June 2005, personnel began to start up the rehabilitated unit. Personnel conducted mechanical runs and then initiated an auto-start sequence. Within 30 minutes, the unit tripped as a result of high thrust bearing temperature. Personnel performed an inspection after the trip and discovered a severely wiped bearing with a babbitt-filled oil reservoir.

FPL Energy personnel then conducted an investigation to determine the cause of failure during start up. During disassembly of the failed bearing, personnel discovered that the round keys that hold the split thrust runner halves to each other were distressed. The two keys are held in place by set screws. Personnel found one ejected key in the thrust bearing oil reservoir; the other key was still in place. Both keys had sheared set screws. And, personnel noticed displacement of about 1/16 of an inch between the thrust runner halves. However, they were not able to target a conclusive root cause for the failure.

To recover from this failure, personnel first reengineered the thrust bearing components. They installed a new split half thrust runner that included a robust key set. Additionally, personnel were concerned that rebabbitting the original backing plate might result in warping. Instead, they decided to install a two-piece babbitt plate. Personnel reassembled the unit and prepared to restart it in September 2005.

During this start up, personnel developed a start-up procedure, intended to address potential issues from the June start-up failure. This included a program of progressive starts and stops consisting of mechanical runs at various speeds, speed-no load runs, and runs of varying duration. Personnel also conducted intermediate inspections and cleaning and scraping to check for damage.

The second start up progressed normally through a run that included flashing the field. The unit was then auto-started and synchronized. Thrust bearing temperatures started to climb dramatically and the unit tripped within three minutes. Upon disassembly of the unit, personnel discovered a preferential wipe in the babbitt that was so severe that the thrust bearing components would have to be either repaired or replaced. Personnel also noted displacement between the two halves of the thrust runner, despite the enhancements made to improve rigidity and stiffness of the keys.

Investigating solutions

At this time, personnel completely removed the thrust bearing from the unit. FPL Energy then assembled a ten-member multidisciplinary team to determine the root cause of the thrust bearing failures and the appropriate corrective actions.

The team worked on the problem for six months. They performed an exhaustive study, evaluated the failed components, and consulted with several thrust bearing performance experts. Eventually, the team came up with one potential root cause and six contributors that enhanced the likelihood of the root cause. The team determined the likely root cause of both failures was the marginal load capacities of the original bearing (subject of the initial start-up failure) and of the reengineered bearing (subject of the second start-up failure).

This thrust bearing, from the 6.6-MW Cataract plant, failed during start up of the rehabilitated unit in June 2005. The oil reservoir of the bearing was filled with babbitt as a result of severe wiping of the bearing.

It has been widely reported that two-piece babbitt bearings on spring beds in hydro service have lower load-bearing capacity than more modern independent pad bearings.1,2 In the case of the thrust bearing at Cataract, calculations indicate that the design load is within 10 percent of the limit for babbitt, which is generally accepted to be 400 pounds per square inch (psi).3 With such a small margin between the design load and the load limit for babbitt, along with other factors at the station – including the situation with AAR that will progressively increase the amount of misalignment – FPL Energy’s focus moved away from refurbishing the existing two-piece spring-bed bearing to retrofitting the unit by installing a higher-capacity bearing.

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Case Study: Thrust Bearing Overheating Problem

For several years, Grant County Public Utility District (PUD) struggled with high temperatures – and subsequent failures – of the thrust bearings of two units at its 907-MW Priest Rapids hydro project. To solve the problem, the utility installed pressure transducers to measure load on the bearings, then used the measurements to more accurately adjust the bearings’ position.
Project background
The Priest Rapids project is on the mid-Columbia River in Washington. The powerhouse is equipped with ten vertical Kaplan turbines. Each umbrella-style generator is rated at 95 MW. Unit commissioning started in 1959 and was completed in 1961.
English Electric designed and manufactured the thrust bearing assembly for each unit. This assembly consists of ten tilting pad shoes supported with an equalizing table. Each shoe is pre-loaded with an adjusting screw. The thrust runner is in two pieces bolted together, and then bolted to a thrust collar. The thrust collar is shrunk fit 0.05-inch onto the generator shaft.
During start up and commissioning, it was necessary to scrape a depression in the babbitt to prevent overheating of the bearings. The scrape patterns evolved through the years with minor bearing wipes, developing their own patterns of areas needing a depression scraped. Often, a bearing set would require a wear-in period and more than one scraping before the temperatures settled. As a result of frequent high temperatures in the thrust bearing assembly, Grant County PUD conducted an inspection and scraping every four years.
Modifying the thrust runner and bearing
In 1995, after several bearing failures, PUD engineers decided to investigate alternatives to hand scraping for solving the overheating problem. On two units they measured bearing movement relative to the support, pressure at the high lift port, and temperature distribution across the leading and trailing edges of the thrust bearing shoe. From an analysis of the test results, the engineers concluded the oil wedge between the thrust runner and thrust bearing (also referred to as an oil film) pressurized the split between the two thrust runner halves, causing it to open slightly. This opening – aided by centrifugal force – allowed oil to flow out the end of the split. The oil leak resulted in unequal load on the thrust bearing, allowing the outer radius of the bearing to move up and briefly make contact with the thrust runner. This contact caused the temperature to rise on the outer radius and across the top of the thrust bearing shoe. As a result of the temperature increase, the bearing deformed into a crowned shape; this caused the top of the bearing to wipe if a depression was not scraped into it.
PUD engineers conducted testing of the thrust bearings and thrust runner to resolve the overheating and failure issues. During data collection, a physical observation of the thrust runner split leak confirmed this unusual phenomena. PUD crews reported that, when the unit was rotated manually (with the high-pressure lift system energized), a stream of oil “squirted” out the split in the thrust runner. Fretting corrosion between the thrust runner and thrust collar near the runner split was attributed to the split becoming pressurized and moving the thrust runner slightly.
As a result of the analyses, the thrust runner on every unit was removed and the thrust runner split machined to achieve a tight fit. The connecting bolts on each thrust runner were shortened to provide more resistance to flexing. All the thrust bearing sets were machined flat without the scraped depression. Another modification involved replacement of a threaded plug for the high-pressure lift system port with a plug that was welded flush. Additionally, all the radial anchor grooves – which were intended to help hold the babbitt in place but can be a source of bonding problems – were machined flat.
From 1995 to 2004, as a result of the modifications to the thrust runner and bearing, PUD was able to discontinue the previously described four-year cycle of scraping, inspection, and maintenance on the thrust bearings. The number of forced outages caused by thrust bearing problems improved from an average of almost one unplanned outage a year to one unplanned outage every three years.
Recent failures
Then, in December 2004, a bearing failure occurred on Unit 1. Three of the ten bearing shoes had sections of babbitt completely removed. This failure was attributed to babbit bond failure on an older rebabbitting process. In the areas of babbitt removal, the bearing shoe had no tin left. The babbitt was previously bonded to the shoe with a trimetal copper process and anchor grooves.
In May 2005, the Unit 1 thrust bearing failed again. A visual inspection showed the babbitt contained fatigue cracking on all the bearings shoes. PUD staff discovered three of the eight bolts between the thrust runner and thrust collar had broken. They also found a crack in the thrust runner split joint, resulting from the additional stress caused by the broken bolts. Powertech Labs performed material failure analysis, consisting of micrographs and scanning electron micrograph pictures. This analysis showed that the three bolts failed in tension due to fatigue.
After this second failure, PUD staff disassembled the entire bearing support mechanism in Unit 1, including the equalizing table, to inspect it for wear or failures. On the surfaces of the thrust runner and thrust collar where they face each other, staff found excessive fretting corrosion. The corrosion caused the thrust collar to be out of tolerance.
To fix the problem, PUD staff would need to machine the thrust collar in place. However, staff concluded in-place machining would be too risky. It would require design and fabrication of a custom machine tool. The high original tolerances for flatness on the thrust collar would be difficult for a custom machine tool. If the flatness tolerance was degraded further during an in-place machine operation, complete disassembly would be required to repair the damage.
The next option – to dismantle the unit even further to machine the thrust collar using a standard available machine tool – was too costly. This option would result in lost power generation from the unit for about two months.
The PUD ultimately decided to replace the thrust bearing runner with a spare and put the unit back in service. The PUD decided the damaged and out-of-tolerance thrust collar would not be repaired at this time.
Before placing the unit back on line, the PUD added monitoring instrumentation to provide feedback on the operating characteristics. PUD personnel placed a resistance temperature detector (RTD) inside the six thrust bearings with no monitoring instrumentation. The PUD already used these RTDs on four of the bearings to measure temperature in the thrust bearing shoe.

Figure 1: Grant County Public Utility District connected pressure transducers to each of ten bearings in Unit 1 at its Priest Rapids hydro project to measure oil pressure at the high-pressure lift port.

In addition, they connected a pressure transducer to each bearing to measure the oil pressure at the high-pressure lift port, as shown in Figure 1 on page 72. The end nut of the bearing was drilled and tapped to allow the pressure at the port of the high-pressure lift system to be measured while the unit was on line. This modification does carry the risk of developing leaks between the oil port and the pressure transducer. A significant leak in the tubing could lead to the loss of the oil wedge and result in a bearing wipe. The risk was minimized by careful installation and pressure testing of all the tubing.
Grant County PUD had one month to assemble the unit and put it into operation, to meet future power demand. The short time available prohibited the use of a less risky, more traditional method of measuring the pressure, such as load cells or submersible transducers installed close to (but not on) the bearing.
In September 2005, the PUD began placing Unit 1 back in service. First, the thrust bearings were pre-loaded with the adjustment screw that holds the thrust bearing shoe up against the thrust runner, according to standard torquing procedures. However, two of the bearings did not leak oil out of the edges of the bearing with the high-pressure lift system energized. If a bearing shoe does not leak oil, the load on that particular bearing is too high. In addition, the unit would not rotate manually.
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60 most influential people in the Hydro Power industry: Part 1

Welcome to International Water Power & Dam Construction’s list of the 60 most influential people in the industry. These people have helped shape the course of the global hydro and dams business over the last 60 years. This list – in alphabetical order – is the result of nominations from contacts and readers around the world, and was decided by a panel of industry experts

Professor Kader Asmal
As chairman of the World Commission on Dams, Professor Asmal headed a multi-stakeholder global review of the development effectiveness of dams. As part of its conclusions in November 2000, the Commission proposed a new framework for decision making in the water and energy sector. This proved highly controversial, sparking a further six years of dialogue that was hosted by the United Nations, culminating in the UN withholding its full endorsement of the WCD report. Nonetheless, the report has had a profound influence on policy and directives at the international level, increasing sensitivities in both environmental and social dimensions.

Professor Jose Antonio Baztan de Granda
Over the past 40 years, Professor Baztan de Granda has designed some of the most important dams in Spain, while also teaching about the subject at the Polytechnical Univerity of Madrid. He has been referred to as one of the most influential dam engineers in Europe.

Geoffrey Binnie (1908-1989)
Geoffrey Binnie was the third generation to head up UK-based Binnie & Partners – the firm started by his Grandfather Sir Alexander Binnie in 1901. He was instrumental in launching the firm into the international large dam business, and worked on a number of important projects such as Gorge dam in Hong Kong, Dokan dam in Iraq and Mangla dam in Pakistan.

Hermod Brekke
Hermod Brekke is Professor Emeritus Dr. Tech at the Norwegian University of Science and Technology in Department for Thermal Energy and Hydropower. His focus of research, for both industry and academia, has been on hydro turbine design, high-head hydraulic systems, and renewables integration for small and large hydropower particularly in developing country contexts. A founding and honorary member of the International Hydropower Association, Brekke has made a considerable contribution to the advancement of hydro power technology.

Dr Roy W Carlson (d 1990)
Dr Carlson is internationally renowned for his research in concrete technology and for the invention of several widely used instruments for gauging the behaviour of concrete. He played a vital role in the construction and testing of dams worldwide.

Linda Church Ciocci
After assuming her position as executive director of the National Hydropower Association in 1991, Linda Church Ciocci helped the organisation double its membership, strengthen its fiscal position, and significantly increase its political stature and public voice in North America.

Professor Ray W Clough
From 1950-1995 Professor Ray W. Clough significantly contributed to the field of earthquake engineering through teaching, research and consulting. His most important research contribution in structural engineering was as a co-developer in the “Finite Element Method” (beginning with a classic paper in 1956 that he co-authored), which forever revolutionized the field of structural analysis and design, as well as many other disciplines that now uses this method for analysis.

A K Chopra
Professor Chopra’s research activities have included studies of structural dynamics and earthquake analysis and design of concrete dams. He has authored more than 300 published papers on this work, a monograph, Earthquake Dynamics of Structures, A Primer, 2005, and a textbook, Dynamics of Structures: Theory and Applications to Earthquake Engineering, 1995, 2001, and 2007.

J Barry Cooke (d 2005)
Often referred to as the ‘father’ of the concrete faced rockfill dam (CFRD), J Barry Cooke is recognised as one of the industry’s most important, and respected, civil engineers. Cooke was co-editor of the one of the dam designer’s most important reference books – Concrete Face Rockfill Dams - Design, Construction and Performance.

Ronald A. Corso
Corso was one of the principal players in developing the US Federal Energy Regulatory Commission’s (FERC) licensing regulations and polices, and was the principal architect of its dam and public safety regulations. An author of more than 75 presentations, he is a sought-after expert on hydro power issues.

Dr. Andre Coyne (1891-1960)
French dam engineer Dr Andre Coyne designed 70 dams in 14 countries, including the Daniel Johnson multiple arch dam on the Manicouagan River in Quebec, and the Malpasset Dam in Southern France. Unfortunately, Malpassaet dam failed in 1959, deeply affecting Coyne, although a later study found that the design of the dam was probably not the reason for its failure. Coyne is also credited with inventing acoustic monitoring procedures and the technique of anchoring structures using pretensioned steel ties.

Paulo T Cruz
Paulo T Cruz’s first work with dams was in the historical Tres Marias Dam and in the past 50 years of his professional life he has worked on countless dams all over Brazil including the Itaipu and Tucurui dams. He is the author of 100 Brazilian Dams – history cases, material, construction and design (1996), consolidating the Brazilian know-how in dam design and construction.

Calvin V Davis (1897-1980)
Calvin V Davis was President of Harza Engineering Company (now MWH) and editor and contributor to the Handbook of Applied Hydraulics, a comprehensive reference for the dam and hydro power design industry. The book was considered a ‘first tier’ reference by the American Association of Dam Safety Officials as late as the year 2000.

Dr Victor De Mello (1926-2009)
The research and developments proposed by Dr Victor De Mello on the behaviour of compacted saprolites and residual soils have influenced dam engineering throughout the world. He participated on the design and construction of some major engineering projects worldwide, including the Tucurui and Yacyreta projects in Brazil.

Mr. Zho Dongru
Mr Zho Dongru is Senior Engineer and Project Manager of China Gezhouba (Group) Corporation (CGGC). Some of his achievements include Gezhouba dam and Three Gorges in China, and Yeywa RCC dam in Myanmar. Mr Zho has spent a lifetime dedicated to dam and hydro power projects in China and Southeast Asia.

Source: http://www.waterpowermagazine.com/story.asp?sectionCode=46&storyCode=2054314

Hydro Headlines

Hydro-Quebec agrees to buy NB Power for C$4.75 billion (Oct 29, 2009)
State-owned Hydro-Quebec, the world’s largest producer of hydropower, will purchase most of the assets of New Brunswick Power in a C$4.75 billion (US$4.45 billion) deal that will lower rates for New Brunswick customers.
NASCAR attraction will be ready for HydroVision International 2010 (Oct 26, 2009)
In addition to networking with hundreds of hydropower professionals, delegates at HydroVision International 2010 can pay a visit to the NASCAR Hall of Fame.
U.S. hydropower consumption increases 5.1 percent (Oct 23, 2009)
During the first seven months of 2009, hydropower consumption in the United States was up 5.1 percent compared with the same period in 2008, according to a report by the Energy Information Administration, the statistical arm of the U.S. Department of Energy.
Exhibition space still available for HydroVision 2010 (Oct 16, 2009)
HydroVision International 2010 is nine months away, but 50 percent of the exhibit hall is already booked as vendors secure a place at the hydropower industry’s biggest conference and trade show.
NHA to release study on job creation (Oct 12, 2009)
During a press conference Oct. 13, the National Hydropower Association will release a comprehensive study indicating the number of jobs the hydropower industry is poised to create in the United States.
Graham wins registration to HydroVision International, online registration now open (Oct 9, 2009)
Wayne Graham, a hydraulic engineer for the U.S. Bureau of Reclamation, will be one of hundreds of hydropower professionals attending HydroVision International 2010 in Charlotte, N.C.
Hydropower allocation triggers New York plant expansion (Oct 7, 2009)
The New York Power Authority has agreed to provide four MW of low-cost hydropower to Metaullics Systems, a move that could create as many as 48 new jobs at the company’s plant in Sanborn, N.Y.
TransAlta, Canadian Hydro agree to buyout offer (Oct 5, 2009)
TransAlta Corp., after increasing its bid 15 percent, has reached an agreement to buy Canadian Hydro Developers Inc. for C$755 million (US$703 million).
Report assigns blame for Russian accident (Oct 5, 2009)
A report by a government watchdog on the Aug. 17 explosion that paralyzed Russia's Sayano-Shushenskaya hydroelectric power plant, claiming 75 lives, says former chief executive of national electricity company Unified Energy Systems (UES) Anatoly Chubais is partially to blame for the conditions that led to the tragedy.
For more go to hydroworld.com
Source: Hydroworld.com

Factors Affecting the Plant Capacity & Discipline of Engineering in a HydroPower Plant

Total Installed Capacity

- Head difference (vertical height) in water levels between two points

- Flow: the volume of water flowing through a area-cross section per unit time

No. of Units and Unit Capacity

• Accessibility and Transportation Limitations
• Availability of Technology
• Operation and Maintenance consideration

Power Developed by a Turbine

Pt = 9.81 x Q x H x η (KW)

Q = Discharge, m3/sec
H = Net Head, m
h = Efficiency of Turbine

ηtur = efficiency of turbine ( 89 % to 95 %)
ηgen = efficiency of generator (96% to 99%)

Discipline of Engineering in a HydroPower Plant

- Civil Engineering - Mechanical Engineering - Electrical Engineering

Civil Engineering further can be categories into Geological Engineering, Hydrological Engineering, Environmental Engineering and Structural Engineering.

Intake Structure and Water Conducting System

- Barrage/Dam - Diversion Structure - Intake Channel - Dislting Chamber - Tunnel - Surge & Drop Shaft - Pressure Shaft - Penstock - Powerhouse - Tail Race Structure

Mechanical Engineering aspect involve design , engineering, manufacturing, testing, selection of turbine and various equipment

Hydro-Mechanical, Power Generating Machines & Auxiliaries

- Intake Gates - Spillway Gates - Trash Rack - Disilting Valve/Gates - Penstock Protection Valve - Surge & Drop Shaft - Turbines & Auxiliaries - Main Inlet Valve - EOT Crane - Fire Protection System - Air Conditioning and Ventilation System - Cooling Water and Compressed Air System - Tail Race Gates

Electrical Engineering aspect involve design , engineering, manufacturing, testing, selection of generators, control systems, switchgear, transmission lines etc.,

Power Evacuating and Transmitting Systems

- Generators and Auxiliaries - Transformers - Control and Protection Systems - Switchyards - Circuit Breaker - Isolators - Current and Potential transformer - Communication Systems - Transmission Lines / Towers

Hydro Turbines

- What is a hydro Turbine

- What are the types of Hydro Turbines

- Bases of Classification of Turbine

- Working Principle of Turbine

- Components of Hydro Turbine

- Brief Comparison of Various Turbine

- Selection of Turbines

- Model Testing of Turbine

Get answers of above quistions in my next posts.

Components of a HydroPower Plant..3

Power House

Power House is a building to house the turbines, Generators and other accessories for operating the machines.

Components of Power House

A. Mechanical Component

Distributor/Spiral Casing- a casing or housing used to distribute the water equally all along the periphery of runner.

Spherical valve or Main Inlet Valve- Valve used to isolate the turbine or machine from water incase non-availability of water for generation or maintenance

Turbine; a hydromachine used to convert the hydraulic energy to mechanical energy

EOT Crane(Electric Overhead Crane); used to lift the equipment of the power house viz., rotor (heaviest component in the power station), stator, shafts, runner and other equipment

B. Electrical Component

Generator; machine used to convert the mechanical energy into electrical energy

Transformers; to step up the generation voltage upto the capacity of grid

Switchyard; is the central protection and metering of the outgoing feeders after stepping up of system voltage using transformer (usually consist of Circuit Breakers, Isolators, disconnect switch, Current transformer, Potential transformer, lighting arrestors etc)

Circuit Breakers: to disconnect the system in case of faults vis-à-vis short circuit, over voltage, under voltage, under frequency, distance faults etc

Disconnect switch/Isolators: to open the circuit as & when desired to take up the system for maintenance

Current Transformer: to step down the system current to the level of 1A/ 5A as the case may be. Used for current measurement and power measurement

Potential Transformer: for Power and voltage measurement

Communication system: consist of wave trap and PLCC for data transfer through power lines.

Transmission lines: using transmission line tower the power is transferred from the generating station to the nearest grid (of desired capacity) General rating of the lines are 11kV ,33kV, 66kV, 132 kV, 220 kV, 400 kV, 750/800 kV.

C. Power House Auxiliaries

Cooling Water system: used to supply the cooling water to Generator air coolers, Turbine bearing, Generator bearing, transformer cooling etc.,

Compressed Air System: used to supply compressed air to various turbine and generator auxiliaries for rotor lifting, generator brakes, service air etc.,

De- watering System: used to de-water the powerhouse in case of seepage, maintenance etc., also used for de-watering the tunnel, penstock.

Air conditioning and ventilation: used to maintain the normal working temperature inside the control room and powerhouse building for efficient working of equipment and operating staff.

Fire protection and detection systems this system is used to protect each Generating equipment and its auxiliaries of the powerplant against the fire hazards. Also, for insurance coverage this system is must and TAC (Terrific Advisory Committee) norms has to be follow for his approval.

Drainage system: used to drain water from powerhouse used for cleaning, water close-let, drinking water etc.

Components of a HydroPower Plant..3

Power House

Power House is a building to house the turbines, Generators and other accessories for operating the machines.

Components of Power House

A. Mechanical Component

Distributor/Spiral Casing- a casing or housing used to distribute the water equally all along the periphery of runner.

Spherical valve or Main Inlet Valve- Valve used to isolate the turbine or machine from water incase non-availability of water for generation or maintenance

Turbine; a hydromachine used to convert the hydraulic energy to mechanical energy

EOT Crane(Electric Overhead Crane); used to lift the equipment of the power house viz., rotor (heaviest component in the power station), stator, shafts, runner and other equipment

B. Electrical Component

Generator; machine used to convert the mechanical energy into electrical energy

Transformers; to step up the generation voltage upto the capacity of grid

Switchyard; is the central protection and metering of the outgoing feeders after stepping up of system voltage using transformer (usually consist of Circuit Breakers, Isolators, disconnect switch, Current transformer, Potential transformer, lighting arrestors etc)

Circuit Breakers: to disconnect the system in case of faults vis-à-vis short circuit, over voltage, under voltage, under frequency, distance faults etc

Disconnect switch/Isolators: to open the circuit as & when desired to take up the system for maintenance

Current Transformer: to step down the system current to the level of 1A/ 5A as the case may be. Used for current measurement and power measurement

Potential Transformer: for Power and voltage measurement

Communication system: consist of wave trap and PLCC for data transfer through power lines.

Transmission lines: using transmission line tower the power is transferred from the generating station to the nearest grid (of desired capacity) General rating of the lines are 11kV ,33kV, 66kV, 132 kV, 220 kV, 400 kV, 750/800 kV.

C. Power House Auxiliaries

Cooling Water system: used to supply the cooling water to Generator air coolers, Turbine bearing, Generator bearing, transformer cooling etc.,

Compressed Air System: used to supply compressed air to various turbine and generator auxiliaries for rotor lifting, generator brakes, service air etc.,

De- watering System: used to de-water the powerhouse in case of seepage, maintenance etc., also used for de-watering the tunnel, penstock.

Air conditioning and ventilation: used to maintain the normal working temperature inside the control room and powerhouse building for efficient working of equipment and operating staff.

Fire protection and detection systems this system is used to protect each Generating equipment and its auxiliaries of the powerplant against the fire hazards. Also, for insurance coverage this system is must and TAC (Terrific Advisory Committee) norms has to be follow for his approval.

Drainage system: used to drain water from powerhouse used for cleaning, water close-let, drinking water etc.,