Function of Runner: The runner is the heart of the turbine.

  This is where water power is transformed into the

rotational force that drives the generator.  Regardless of the runner type, its buckets or blades are responsible for
capturing the most possible energy from the water.  The curvature of each surface, front and rear, determines
how the water will push its way around until it falls away.  Also keep in mind that any given runner will
perform most efficiently at a specific Head and Flow. The runner should be closely matched to your site
characteristics.
Look for all-metal runners with smooth, polished surfaces to eliminate water and air turbulence.  One-piece,
carefully machined runners typically run more efficiently and reliably than those that are bolted together. 
Bronze manganese runners work well for small systems with clean water and Heads up to about 500 feet. High-
tensile stainless steel runners are excellent for larger systems or abrasive water conditions.  All runners should
be carefully balanced to minimize vibration, a problem that not only affects efficiency but can also cause
damage over time.
Rotor having a series of vanes mounted on it is known as runner.
Guide Vanes: Main function:
Adjust the turbine load
The guide vanes consist of number of blades that can be adjusted in order to increase or reduce the flow rate
through the turbine. The vanes are arranged between two parallel covers normal to
the turbine shaft.
The function of guide vanes in a reaction turbine is to
allow the water to enter the runner without allow the water to flow over them, without
[A]. [B].
shock forming eddies

allow the required quantity of water to enter

[C]. [D]. all of the above
the turbine

Spiral casing: The spiral casing around the runner of the turbine is known as the volute casing or scroll case.
Throughout its length, it has numerous openings at regular intervals to allow the working fluid to impinge on
the blades of the runner. These openings convert the pressure energy of the fluid into momentum energy just
before the fluid impinges on the blades. This maintains a constant velocity despite the fact that numerous
openings have been provided for the fluid to enter the blades, as the cross-sectional area of this casing decreases
uniformly along the circumference.
Main Inlet Valve (MIV): Functions
1) Main inlet valve works as the gate valve isolating valve in the water conductor system.
2) It is located before turbine and allows water flow from penstock to turbine.
3) MIV acts as closing valve and cuts the flow of water during an emergency trip.
4) They are of following type.
5) Butterfly valve (up to 200m head)
6) Spherical valve (more than 200m Head)

1
Shaft seal: Also called Oil Seal, in machinery, a device that prevents the passage of fluids along a rotating
shaft. Seals are necessary when a shaft extends from a housing (enclosure) containing oil, such as a pump or
a gear box.
A common type of shaft seal consists of an elastomer (elastic rubberlike) ring bonded to a metallic ring that is a
press (tight) fit in the hole in the housing through which the shaft extends. The sealing is done by a lip on the
elastomer ring that is pressed snugly around the shaft by a helically wound garter spring. When properly
designed and installed, the lip rides on a film of lubricant about 0.0001 inch (0.0025 millimeter) thick. If the
film gets too thick, fluid leaks; if it is too thin, the lip gets hot, and the seal may fail. Leather, synthetic rubber,
and silicones are among the materials used for the sealing ring.
Water retaining sealing components in the turbine includes the seal for the turbine shaft and the wicket gate
stem seals. Shaft seals are typically either packing boxes with square braided packing or for high speed units a
mechanical seal is required. Wicket gate stem packing is usually either a square braided compression packing, a
V type or Chevron packing, or some type of hydraulic elastomer seal. Although in the truest sense any sealing
components on a turbine could be a performance issue, since any leakage that by-passes the turbine runner is a
loss of energy, the leakage into the wheel pit is considered insignificant to the overall flow through the turbine.

Guide Bearing: The function of the turbine guide bearing is to resist the mechanical imbalance and hydraulic
side loads from the turbine runner thereby maintaining the turbine runner in its centered position in the runner
seals. It is typically mounted as close as practical to the turbine runner and supported by the head cover. Turbine
guide bearings are usually either oil lubricated hydrodynamic (babbitted) bearings or water lubricated (plastic,
wood, or composite) bearings.

Nozzle: A nozzle is a device designed to control the direction or characteristics of a fluid flow (especially to
increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying
cross sectional area, and it can be used to direct or modify the flow of a fluid (liquid or gas). Nozzles are
frequently used to control the rate of flow, speed, direction, mass, shape, and/or the pressure of the stream that
emerges from them. Nozzle with flow regulating device.
Butterfly valve: A Butterfly valve is a quarter-turn rotational motion valve that is used to stop, regulate, and
start flow. Butterfly valves are easy and fast to open. A 90° rotation of the handle provides a complete closure
or opening of the valve. Large Butterfly valves are usually equipped with a so-called gearbox, where the hand
wheel by gears is connected to the stem. This simplifies the operation of the valve, but at the expense of speed.
Butterfly valves has a short circular body, a round disc, metal-to-metal or soft seats, top and bottom shaft
bearings, and a stuffing box.

Typical applications of Butterfly valves:

A Butterfly valve can be used in many different fluid services and they perform well in slurry applications. The
following are some typical applications of Butterfly valves:

 Cooling water, air, gases, fire protection etc.

 Slurry and similar services
 Vacuum service
 High-pressure and high-temperature water and steam services

Advantages of Butterfly valves

 Compact design requires considerably less space, compared to other valves
 Light in weight

2
  Quick operation requires less time to open or close
 Available in very large sizes
 Low-pressure drop and high-pressure recovery
Disadvantages of Butterfly valves

 Throttling service is limited to low differential pressure

 Cavitation and choked flow are two potential concerns
 Disc movement is unguided and affected by flow turbulence

Needle valves: Needle Valves are used to make relatively fine adjustments in the amount of fluid flow.

The distinguishing characteristic of a needle valve is the long, tapered, needlelike point on the end of the valve
stem. This NEEDLE acts as a disk. The longer part of the needle is smaller than the orifice in the valve seat and
passes through the orifice before the needle seats. This arrangement permits a very gradual increase or decrease
in the size of the opening. Needle valves are often used as component parts of other, more complicated valves.
For example, they are used in some types of reducing valves.

Needle Valve Applications

Most constant pressure pump governors have needle valves to minimize the effects of fluctuations in pump
discharge pressure. Needle valves are also used in some components of automatic combustion control systems
where very precise flow regulation is necessary.

Deflector:
Jet deflectors have the function of diverting the water flow or part of it between the nozzle and the rotor in such
a way that it does not hit the buckets. These may be used for an emergency stop or to regulate the turbine.
If the power has to be reduced quickly, the governor moves the jet deflector into the jet, thus diverting part of
the water from the buckets and reducing the power transferred to the rotor. The governor then adjusts the
discharge by slowly moving the needle. Meanwhile the deflector is gradually withdrawn.
A deflector is a device provided at the tip of the nozzle to deflect the path of a part or the full jet issuing from
the nozzle in such a manner that the deflected part of the jet does not impact the bucket and falls away from the
runner. The deflector serves another purpose of protecting the jet from the exit water spray from the runner, to
some extent. The deflector servomechanism is connected by link mechanisms with the control valve of the
needle servomotor.

Hydraulic Pumps: A hydraulic pump is a mechanical source of power that converts mechanical power into
hydraulic energy (hydrostatic energy i.e. flow, pressure). It generates flow with enough power to overcome
pressure induced by the load at the pump outlet. When a hydraulic pump operates, it creates a vacuum at the
pump inlet, which forces liquid from the reservoir into the inlet line to the pump and by mechanical action
delivers this liquid to the pump outlet and forces it into the hydraulic system. Hydrostatic pumps are positive
displacement pumps while hydrodynamic pumps can be fixed displacement pumps, in which the displacement
(flow through the pump per rotation of the pump) cannot be adjusted, or variable displacement pumps, which
have a more complicated construction that allows the displacement to be adjusted. Hydrodynamic pumps are
more frequent in day-to-day life. Hydrostatic pumps of various types all work on the principle of Pascal's law.

Types of Pumps:
Pumps can be broadly classified into:
• Kinetic Pumps: (Head Generators)
3
‰ Axial Pump
‰ Centrifugal Pump/Radial flow Pumps
‰ Mixed Flow Pump

 In axial flow pumps, the entry and exit is parallel to the axis of the impeller.
 In radial flow pumps, the exit is perpendicular to the flow at the inlet.
 In mixed flow pumps, the flow at the exit of the impeller is at an angle to the axis of impeller.

• Positive Displacement Pumps: (Flow Generators)

‰ Reciprocating Piston or Plunger
‰ Gear Pump
‰ Screw Pump
‰ Lobe Pump

During selection of the type of pump three groups of criteria can be distinguished:

1) Process and design requirements

4
2) Nature of pumped medium: Different types of pumps are suitable for pumping of various media differing in
viscosity, toxicity, abrasiveness and many other parameters. So screw pumps can pump viscous media with
different inclusions without damaging structure of the medium, and can successfully be used in food-processing
industry for pumping of jams and pastes with various fillers. Corrosion properties of the pumped medium
determine material design of the selected pump, and toxicity – degree of its air-tightness.

3) Key design parameters (Capacity, Head and Power Consumption):

Capacity (delivery, flow rate) – volume of medium pumped by a pump per unit of time. It is denoted by letter Q
and has dimension in m3/h, l/s, etc. Flow rate quantity includes only factual volume of displaced fluid ignoring
return leakages. The theoretical and factual flow rate ratio is expressed by volumetric efficiency quantity:

But in modern pumps thanks to reliable sealing of pipelines and joints the factual capacity coincides with
theoretical. In the majority of cases a pump is selected for the particular pipeline system and flow rate value is set in
advance.

Head – energy imparted by pump to the pumped medium and attributed to unit of pumped medium mass. It is
denoted by letter H and has dimension in meters. It should be clarified that the head is not geometrical
characteristic and is not the height to which a pump can lift pumped medium.

Power consumption (shaft power) – power consumed by pump during operation. Power consumption differs
from pump useful capacity consumed directly for imparting of energy to the pumped medium. Part of consumed
power can be lost due to leakages, bearings friction, etc. Performance factor determines ratio between these
quantities.

Reciprocating Pump(Positive displacement pumps): The positive-displacement principle is well illustrated in

the reciprocating-type pump, the most elementary positive-displacement pump, Figure 1. As the piston extends,
the partial vacuum created in the pump chamber draws liquid from the reservoir through the inlet check valve
into the chamber. The partial vacuum helps seat firmly the outlet check valve. The volume of liquid drawn into
the chamber is known because of the geometry of the pump case, in this example, a cylinder.

5
As the piston retracts, the inlet check valve re-seats, closing the valve, and the force of the piston unseats the
outlet check valve, forcing liquid out of the pump and into the system. The same amount of liquid is forced out
of the pump during each reciprocating cycle.

All positive-displacement pumps deliver the same volume of liquid each cycle (regardless of whether they are
reciprocating or rotating). It is a physical characteristic of the pump and does not depend on driving speed.
However, the faster a pump is driven, the more total volume of liquid it will deliver.

Operation and Maintenance:

Operation and Maintenance of hydro power stations must aim at reducing failure rate by ensuring smooth
operational levels of the power utility. This can be done by adopting timely preventive maintenance schedule
regarding all vital areas of the power project. Engineers are well-advised here to follow the well-known dictum
“Prevention is better than cure”.
Every equipment and structure has its own life to serve the purpose for which it is meant. A well maintained
equipment not only serves its purpose efficiently, economically and reliably but also exceeds its expected life
time. The lack of proper operation and adequate maintenance results into, not only higher failure rates and
increase in the downtime of individual generating units, but also effects on efficient performance of the whole
power system causing:

 A low degree of equipment service reliability;

 Loss of service of electric power to consumers, and
 Power energy losses to the utility(ies) in an economically unacceptable manner.

Reducing the malfunctioning of any of the components of the generation, transformation and transmission
systems to a minimum should be the main aim of the inspection, testing, maintenance, repair, overhauling, etc.

Types of Maintenance:

The Alternate Hydro Energy Centre, Indian Institute of Technology (IIT) Roorkee gives five types of
maintenance, while the Bureau of Reclamation, U.S. Department of Interior gives four types. Two types

6
(Preventive Maintenance and Reliability-Centred Maintenance), are mentioned in both the documents, while the
Predictive Maintenance stated in IIT document is similar to Condition-Based Maintenance given in the
document of Bureau of Reclamation.

a. Preventive Maintenance: Preventive Maintenance is planned/routine or scheduled maintenance. The intent

of preventive maintenance is to “prevent” problems or failures before they take place by following routine and
comprehensive maintenance procedures. It is designed to improve equipment life and avoid any unplanned
maintenance activities. Preventive maintenance covers inspection, replacement, repair of any equipment or
component based on time and set parameters. It includes painting, lubrication, cleaning, adjusting and minor
component replacement to extend the life of equipment and facility. Its main purpose is to minimize breakdown
and excessive deterioration and to achieve fewer, shorter, and more predictable outages.

b. Reliability Centered Maintenance: This sort of maintenance is defined as “a process used to determine the
maintenance requirements of any physical asset in its operating context”. It is ongoing process which
determines the mix of reactive, preventive and proactive maintenance practices to provide reliability at the
minimum cost. It recognizes that not all equipment’s in facility are of equal importance for generation as well as
plant safety. It recognizes that design and operation of each equipment differs; and, therefore, possibility of
failure differs from equipment to equipment. In this program diagnostic tools and measurement are used to
assess when a component is near failure and should be replaced. In this program basic thrust is to eliminate
more costly unscheduled maintenance and to minimize preventive maintenance. In this type of maintenance,
unimportant maintenance activities are left to reactive maintenance approach. The goal, thus, of this program is
to provide the appropriate amount of maintenance at the right time to prevent forced outages while at the same
time eliminating unnecessary maintenance.

c. Predictive Maintenance: This sort of maintenance ensures ability to judge when a part of equipment is
going to fail and replace the same before it does. Usually, it requires some form of testing and analysis which
helps predict an eminent failure. Predictive maintenance can be used in conjunction with preventive
maintenance practices. In hydropower stations, there are many monitoring systems, which can be used to
predict problems and possible failures. These include vibration monitoring, oil analysis, temperature, system
loading, IR values of generation, efficiency in power generator output, and leakages of oil and water. All of
these data can be captured, tracked and analyzed through computer system. The results of analysis of data can
predict the future.

d. Proactive Maintenance: Most recent innovation in maintenance is called proactive. It utilizes a technique
called “root cause failure analysis”. In this type of maintenance primary cause of failure is diagnosed and
corrected.

e. Reactive (Run to Failure) Maintenance: This is sometimes called crisis maintenance or hysterical
maintenance. This has been dominant form of maintenance for long time and its costs are relatively high
because of the unplanned downtime, damaged machinery and overtime expenditure. Run to failure should be a
very small part in a modern maintenance program. Planned maintenance is preferred over this type so as to
reduce downtime of machine and avoid uncalled for outages.

Basic guidelines of O & M: In the present era of advancement of technology, automation, computerization,
enhanced human capabilities etc., many things have become possible. A number of hydropower plants could be
found under operation in the developed countries even unattended. However, the need of routine inspection,
servicing, performance testing, undertaking of timely corrective measures such as repairs, overhauls,
replacement of parts, etc. cannot completely be avoided. The levels of maintenance requirement differ from
component to component depending upon their functions and conditions under which they are operated.
Planned or routine/preventive maintenance helps reduce not only losses in revenue, but also saves from
disastrous happening due to failure to structure(s), and breakdown of equipment at the time when their uses are
7
most needed, because the inspection and performance tests during the routine maintenance make possible to
detect or predict deficiencies in the equipment/structure(s) involved in the hydropower generation and
transmission for timely planning of rectification, repairs and/or replacement.

Operation and maintenance of hydropower stations must aim at reducing failure rate by ensuring smooth
operational levels of the power utility. This can be done by adopting timely preventive maintenance schedule
regarding all vital areas of the power project.

4.1.3.1 Operation
Good practices in Operation of Hydropower stations shall be such that the downtime of individual generating
Unit & Plant should be minimum. The operational reliability of the generating units of the hydropower stations
shall be such that whenever the grid demands, it should be available for generation. Some of aspects, which can
be taken into consideration, in Operation of hydropower stations, are given below:
 Each failure/tripping occurrence must be questioned with basic minimum three questions: (a) why this
occurred? (b) How this occurred? (c) What is to be done to avoid its reoccurrence? This will definitely reduce
failure rate to the greater extent.
 Since it is important to adopt timely preventive maintenance schedules covering all vital areas and plants, the
detailed Daily, Weekly, Monthly, Quarterly, Annually and Capital Maintenance Sheets should be maintained
properly.
 During replacement of any part or equipment after its full utilization or breakdown, it should be ensured that
the replaced part or equipment should be of improved version & of latest technology having longer durability to
meet all desired requirement so as to increase plant efficiency and reliability.
 Operating conditions should continuously be monitored and recorded. Records are very important to diagnose
the cause of fault/ failure/ replacement & to determine residual life. Early action can be taken before any type of
failure.
 Even though original equipment manufacturers recommend max./min. permissible parameters for their
equipment, the records/ experience/past history play important role to set limiting values of parameters of these
equipment’s, as characteristics of identical equipment vary from unit to unit and required to monitor its set
values.
 On the basis of past history/records & recommendations of manufacturers maintenance schedules can be
framed. Breakdowns/forced outages can be minimized by proper follow-up of the maintenance schedules based
on recommendations of manufacturers. Life of the equipment, thus, can be enhanced.
 Starting/stopping of the units shall be planned to be minimum to increase the life.
 Procurement of the equipment spare parts should be planned as per the rate of the consumption, based on
minimum requirement to optimize the inventory.
 Optimum utilization of the manpower & material to be planned.
 It would be beneficial to arrange training for O & M staff to refresh their knowledge to give advanced
technical information to improve work quality & quantity. The training of O & M staff should be mandatory for
transfer of O & M knowledge from original
equipment manufacturers.
 Interaction amongst working staffs at various power stations in the country needs to be organized to improve
performance of plant and equipment in totality so as to implement good Operation & Maintenance Practices.
 Provision of “On Line Condition Monitoring System” on generator, turbine and main transformers could be
considered for installation on all existing power stations.
 Afforestation in catchment area will help reduce silt flow and conserve water, for which the catchment area
treatment studies for the stations in operation should be carried out and as per recommendations of the studies,
the power station should carry out afforestation work in the catchment area.

8
4.1.3.2 Maintenance
some of the practices to be adopted at hydropower station for maintenance are broadly given below.
 Water Intake, Water Conduit System and Associated Equipment:
Water storage (Reservoir) & water conductor system comprising of intake, headrace tunnel, surge shaft,
emergency valves & pressure shafts, penstock, main inlet valves are very vital organs of a hydropower plant.
Some of the additional points as
mentioned below also need to be considered:
- Cavitations & erosion at top portion due to rushing of air during fill up,
- The inspection schedule for the durability of anticorrosive paints used,
- Replacement schedule for various vulnerable parts such as bends, open
conduits, etc.,
- Due to humidity, open conduit deteriorates from outside. As such inspection &
cleaning to be carried out from time to time at regular intervals,
- Anticorrosive-painting schedules followed,
- Timely operation & maintenance of the cranes & hoists,
- Healthiness of control & protection for isolating gates/valves & for cranes/hoists,
- Maintenance of trash-rack/intake gate filter, and
- Maintenance of communication systems, availability of power supply, equipment
for emergency operations, approach roads, etc.

Following maintenance are need to turbine and governor as follows:

Turbine
- Periodic ultrasonic,
- Polishing of the various under water parts of the turbines once in a year to minimize the white pitting,
- Inspection & testing of the runners from experts to decide residual life so as to initiate action for procurement
of runners for replacement,
- Inspection of labyrinth seals in case of reaction turbines,
- Painting of runner housing with anticorrosive/tar based paints,
- Applying anti-erosion coating to the runner, and
- Checking of brake jet operation in power stations having Pelton turbines once in three months.
Governor:
- Purification of hydraulic oils by centrifugal as well as electrostatic liquid cleaner,
- Periodic maintenance of the servo valves and motors after carrying out inspection of the pistons & housings of
the servo valves and motors for their worn-out parts. Replacement of the leaking seals, and
- Survey of the component failure & procurement of the same and maintain minimum inventory

Governor Compressor air Cleaning of governor compressor air filters and checking ofoil
filters (Weekly check) levels.

Monthly Maintenance Checks:

During monthly maintenance checks, all the checks covered in weekly maintenance checks as indicated above

9
are carried out, but while carrying out these checks more attention is paid and short shutdowns (if required) for
rectification are taken.

i. Filter the throttle; replace the same if found damaged.

Governor Mechanical
ii. Attend leakage of oil through pipe line joints and valves.
Cabinet (if applicable)
iii. Auto rod setting. Set the same, if found disturbed.
(Yearly check)
iv. Alignment of feedback wire rope pulleys.

Five Yearly Maintenance:

After every five years it is necessary to inspect / check the machine more critically for abnormalities like fatigue
defects for excessive wear and tear of some parts or any change in original parameters/clearances, etc. This
exercise becomes very essential in cases where performance level has been observed to have gone down in five
years of operation.

Capital maintenance or overhauling of hydro-turbine set is usually done after about 10 years of operation or as
and when necessary. During this maintenance, the whole unit is to be stripped off and all the defective/worn out
parts/ components repaired/ replaced with new ones. Then the unit is re-commissioned as per originally
established commission practice of the power plant. After capital maintenance, the units are subjected to all the
periodic maintenance outlined in above sections before it reaches the next cycle of capital maintenance.
Following checks are to be exercised during capital maintenance of hydro turbine set.

i. Cleaning and checking OPU pumps. Replace bushes, bearings,

etc., if found worn out. Attend also the pump motors.
ii. Clean OPU sump and pressure accumulator and refill with filtered
oil.
iii. Attend oil pipeline flanges and valves for leakage.
iv. Check setting of pressure switches installed for Auto operation for
Governor OPU pumps.
v. Attend Governor mechanical cabinet (if provided) for leakages,
loose links. Clean main and pilot slide valves. Set Auto rod as per
designs. Alpha Beta setting may also be checked in case of Kaplan
turbine.
vi. Check electrical circuit. Tightening of all the connections should
also be done.

Governor
Governors are of four types (i) mechanical (ii) governor employing magnetic amplifier (iii)
governor employing electro-hydraulic amplifier, and (iv) digital governor. The digital type of
the governor is maintenance free and fast response modern day governor, while the other
three types of governor may require maintenance because of the following reasons:
 Chocking of oil parts and throttles.
 Wearing out of throttles due to which oil leakage becomes more and readjustment of
governor becomes essential. In this case, governor should be opened and all the
throttles, etc. should be cleaned. Filters also should be cleaned, and after cleaning
and reassembly, governor parameters and characteristics should be readjusted so
that there is no hunting of the governor.

Governing Oil System

10
The normal problem, which had been faced in different hydropower stations, is entry of water in the governing
oil system particularly from top cover through oil leakage pumps which caters leakage of servomotor oil. Its
sump being located well below the level of servomotors in the top cover may not be properly sealed, thus
providing access to the top cover water which may ultimately delivered to the OPU sump. To eliminate this
problem the oil leakage unit delivery should be isolated from the OPU sump and connected to a separate tank.
The oil sump should be properly cleaned and filled with filtered oil. The oil samples should be got tested for
verification of the desired properties. Regular centrifuging of oil with the help of De-Laval type oil purifying
machine would go a long way in enhancing the life of the oil. In certain case, oil retained its properties even up
to 15 to 20 years of continuous use. During annual overhauling, the OPU sump and pressure accumulator
should be completely emptied and cleaned. The strainers should be inspected and repaired, if necessary. The
OPU pumps require maintenance when they develop excessive noise or vibration. This may be due to some
worn out bearing, screw/impeller and body of the pump, which would be replaced. Sometime oil level in sump
is found decreased which may be due to system leakage in the system. This requires to be attended.
4.5.2 Maintenance of Hydro-turbine & Auxiliaries
4.5.2.1 Routine Inspection and Maintenance
The following daily, weekly, monthly, annual and five yearly inspection checks are to be
done for the routine maintenance of hydro-turbines & auxiliaries.

Daily Maintenance Checks:

Items/Components/parts to
S. No. Checked for
be checked
Foundation gallery parts and Any leakage in draft tube manholes, spiral casing
1.
expansion joints manhole, expansion joint, cooling water tapping.
Vacuum Breaking Valve/ Air The working of vacuum bearing valve and see that there is
2.
Admission Valve (if provided) no abnormality in the springs, seals, etc.
i. The position of leakage of the seals and see that there
is no excessive splashing and water level do not rise in
3. Water Seal
top cover.
ii. Note the water pressure of water sealing.
i. Oil levels (stand still machine/running machine).
ii. Note the temperature of bearing and check that the
temperature of oil and guide bearing pads are within
limit.
4. Turbine guide bearing iii. Note the maximum and minimum temperature and
compare with readings of the previous day.
iv. Any oil leakage from the bearing housing and check
that oil is flowing above the bearing pads.
v. Check cooling water system and oil coolers.
i. Any leakage from GV (Governor) servomotor and its
5. Guide apparatus piping
ii. Guide vane link breakage.
i. Any leakage from pipe line joints.
6. Oil Leakage Unit
ii. Satisfactory running on "Auto"
i. Main supply "ON".
ii. Vibration/ noise in the pump motor
7. Tap cover drain system
iii. Any leakage from the water piping
iv. Working and water pressure of the ejector
Centralized Grease i. Any leakage from grease pipes, unions and nipples.
8.
Lubrication System ii. Grease container is filled with grease.
11
 i. If there is any abnormal sound in the running of the
motor and pump unit of OPU.
ii. The oil level in pressure accumulator and oil sump.
iii. Any oil leakage from oil piping and its valves.
9. Oil pressure System iv. Oil level recorders as also oil film in the tailrace.
v. Overheating of motor.
vi. Note the timing of OPU pumps running and compare
with previous day running hour. Any increase in leakage
in the system can be watched.

Weekly Maintenance Checks:

Items/Components/parts to
S. No. Checked for:
be checked
i. Grease in the grease container.
Greasing of Guide vanes and
ii. Any leakage.
servomotor with centralized
1. iii. Working of end pressure relay and solenoid valves,
grease lubrication system and
if
manually.
defective, should be reported.
Cleaning of throttle filters (if provided) in the governor
2. Throttle filters
mechanical cabinet.
Governor Compressor air Cleaning of governor compressor air filters and
3.
filters checking of oil levels.
Checking physically oil of OPU of the running machine
Oil of OPU of the running after taking sample through sampling cock, do the
4.
machine crackle test for detecting presence of water. Take
remedial measures.
5. All the bearings Oil level of all the bearings.
Coupling flanges and oil Check working of shaft at coupling flange and at oil
6.
header servo tube. header servo tube.
7. Cooling system Any leakage.

Monthly Maintenance Checks:

During monthly maintenance checks, all the checks covered in weekly maintenance checks as indicated above
are carried out, but while carrying out these checks more attention is paid and short shutdowns (if required) for
rectification are taken.

Annual Inspection and Maintenance:

After successful running of plant for about one year, few weeks are required to be allocated to
inspect rotating parts, control equipment and measuring instruments, etc. and analyze cause of
change in the performance characteristics (if any). Modify/repair/replace, whenever required, the
worn out parts in order to prevent forced outage of machine at later date. Following inspection
and checks should be carried out during maintenance:

Items/Components/p
S.
arts to be inspected Checked/ inspected for and remedial measures taken
No.
and checked
12
 i. Condition of water path system. The damage due to
cavitations and wear to be rectified.
1. Water Path Parts ii. Painting of spiral casing, penstock, draft tube.
iii. Condition of stay vanes, guide vanes and under water parts
for wear, tear, etc.
fited by welding and grinding. It is to be ensured that hydraulic profile of
the blades is not disturbed.
2. Runner
ii. The runner blade seals to be checked by pressurizing the
system, change seals (if necessary).
i. The pressure of rubber sealing cords and the tightness of the
rubber sealing between the adjacent guide vanes in fully
closed position of guide apparatus (wherever provided).
ii. Guide vane bedding in fully closed position.
iii. Change grease in the regulating ring.
iv. Replace damaged shear pins.
v. Check cup sealing of guide vane journals and replace (if
3. Guide Apparatus
necessary).
vi. Check the bushes of guide vanes and change the worn out
bushes of guide vane journals (if possible).
vii. Water jets, needles, deflectors and their servo-mechanism (if
the turbine is Pelton).
viii. Inspect the servomotor and change the seal (if these are
worn out).
i. The condition of rubbing surfaces of guide bearing. Clean the
surface and polish it with the help of chalk powder.
ii. Adjust the clearances by moving the segments with the help
4. Guide Bearing
of adjusting bolts.
iii. Thorough cleaning of housing is necessary.
iv. Check all the RTDs and TSDs, replace damaged ones.
i. The condition of rubbing surface of sealing rings. In case
Shaft Gland Seal and found damaged, change the same.
5.
Air Seal ii. Pipe lines and piping joints for leakage. If found any, attend
the same.
i. The functioning of emergency slide valve and the condition of
inner surface.
6. Emergency Slide Valve
ii. Swift return of the valve in its original position after
emergency operation should also be checked.
Centralized Grease Satisfactory working of CGLS system and attend wherever fault
7.
Lubrication System is located.
i. Leakage and attend leakage (if any) from any valve or
flanged joints, etc.
ii. Provide proper lubrication to the bearings of pump motor.
8. OPU iii. Filter and repair, if required.
iv. Clean oil sump, refill with centrifugal oil.
v. Setting of the pressure relays for proper sequence of
operation of pumps.
i. The satisfactory working on auto as well as manual.
9. Oil Leakage Unit ii. Clean the tank.
iii. The pipeline joints and valve for leakage, attend wherever
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 necessary.
i. All the oil and water pipe lines for leakage and attend if
10. Oil Cooling Unit necessary.
ii. The satisfactory working of all cooling unit.
i. Filter the throttle; replace the same if found damaged.
Governor Mechanical ii. Attend leakage of oil through pipe line joints and valves.
11.
Cabinet (if applicable) iii. Auto rod setting. Set the same, if found disturbed.
iv. Alignment of feedback wire rope pulleys.

Five Yearly Maintenance:

After every five years it is necessary to inspect / check the machine more critically for abnormalities like fatigue
defects for excessive wear and tear of some parts or any change in original parameters/clearances, etc. This
exercise becomes very essential in cases where performance level has been observed to have gone down in five
years of operation.
4.5.2.2 Capital Maintenance
Capital maintenance or overhauling of hydro-turbine set is usually done after about 10 years of operation or as
and when necessary. During this maintenance, the whole unit is to be stripped off and all the defective/worn out
parts/ components repaired/ replaced with new ones. Then the unit is re-commissioned as per originally
established commission practice of
the power plant. After capital maintenance, the units are subjected to all the periodic maintenance outlined in
above sections before it reaches the next cycle of capital maintenance. Following checks are to be exercised
during capital maintenance of hydro turbine set.

S.
Items Checks to be exercised
No.
i. Dismantling, inspection, cleaning, measurement of clearances, polishing of
guide pads, centering of shaft, reassembly, setting of
1 . Turbine Bearing clearances, filling of oil sump with filtered oil.
ii. Checking of the temperature sensing device. Replace with new
ones, if necessary.
Gland Seals and
Dismantling, inspection, cleaning and reassembly. Replacing of
2. Isolating Air Inflated
worn out rubber flaps or carbon segments, if necessary.
Seals
Vane Dismantling for inspection and cleaning. Reassembling and
3.
Servomotor replacing the seals with new ones, if necessary.
Guide Vanes Bush Dismantling, cleaning and inspection for wear and tear, replacing
4.
Housing with new ones, if found necessary. Replace seals as well, if necessary.
i. Guide vanes are reconditioned and proper bedding in closed
position is ensured.
5. Guide Vanes
ii. Repair of guide vane journals to remove ovality.
iii. Alignment of complete guide vane with all journals.
6. Governor i. Cleaning and checking OPU pumps. Replace bushes, bearings,
etc., if found worn out. Attend also the pump motors.
ii. Clean OPU sump and pressure accumulator and refill with filtered
oil.
iii. Attend oil pipeline flanges and valves for leakage.
iv. Check setting of pressure switches installed for Auto operation for
OPU pumps.
v. Attend Governor mechanical cabinet (if provided) for leakages,
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 loose links. Clean main and pilot slide valves. Set Auto rod as per
designs. Alpha Beta setting may also be checked in case of Kaplan
turbine.
vi. Check electrical circuit. Tightening of all the connections should
also be done.
i. Inspect condition of spiral casing, runner chamber, draft tube cone,
compensating ring and draft tube, and rectify defects by welding
and grinding.
7. Under Water Parts
ii. Penstock filling line valve, spiral drain valve, draft tube drain valve
should also be checked and repaired.
iii. Cleaning and painting of penstock, spiral casing and draft tube liner.
i. Dewatering of draft tube.
ii. Fabrication of platform in the draft tube for inspection of runner
chamber/static labyrinths.
iii. Inspect blades/ buckets of the runner and make up profile by
8. Runner welding and grinding, if found damaged due to erosion and
cavitations. After weld repair, heat treatment and dynamic
balancing is must before installation.
iv. In case the runner is found to be irreparable, arrange to replace the
same with new one.
i. Drainage pump motor set for top cover drain.
 Inspect top cover drain system, overhaul the ejector and drainage pump.
 Check pipelines and valves. Replace gasket and other parts, if necessary.
ii. Oil cooling unit
 Overhaul cooling pumps.
 Attend all the valves and pipe line for leakage.
iii. Centralized Grease Lubrication System.
 Overhaul greasing pump.
 Check whole greasing lines. Replace worn out valves and gasket, etc.
9. Turbine Auxiliaries  Check all the nylon pipes connected with the guide vane bushes. Replace
damaged pipes.
 Check that all the guide vanes are receiving grease properly.
iv. Clean Water System
 Clean water pipes are dismantled, cleaned, reassembled with new gaskets.
 All the valves are attended for any leakage.
v. Oil leakage unit.
 Check the oil leakage unit and overhaul the pumps.
 Clean tank and check that float is properly working.
 Check all the pipe lines and valves for leakage.

4.5.2.3 Typical Problems in the Maintenance of Hydro-turbines

The typical problems in the maintenance of hydro-turbines encountered are damages in runner chambers and
runners due to erosion, cavitations & cracking, failure of turbinebearings and leakage of water through guide
vane seals and turbine gland seals etc. Theyare discussed in the following paragraphs.
Erosion
The damages in runners, chambers, guide vanes and other underwater parts have assumed serious proportions
especially in the Nepalese context due to predominance of run-of-river hydropower plants in the Nepal Power
15
System. The rivers of Nepal carry enormous silt loads particularly during summer monsoon so much, so that the
power stations had to be closed down to prevent serious damage to the turbine parts and the water conveyance
system. Even with greater attention being paid to desilting arrangements, heavy damages have been observed on
the runner, labyrinth seals, guide vanes, inlet valves, shaft seals and draft tube cone. The wear due to silt occurs
so fast that the unit has to be taken out for reconditioning every few years. The remedy appears to lie in
effective desilting arrangements and manufacturing of turbine parts with harder and erosion resistant materials
like stainless steel of proper grade. In the Chilime hydropower plant (22.1 MW), even in the peaking pondage
reservoir in the water conveyance system enroute to powerhouse, sediments used to be trapped. The annually
removed sediment from the pondage reservoir amounted in the range from 10,000 to 12,000 m3 per year.
Cavitations& Cracking
The phenomenon of cavitations occurs due to the vaporization of flowing fluid in a zone of excessive low
pressure. Normally the discharge side surface of buckets or blades, areas on the crown on the throat ring and the
tip of blades and the upper portion of draft tube liver are affected by the action of cavitations. The problem of
cracking of runner and pelton bucketscan be due to

(i) faulty design and fabrication, (ii) poor metallurgy, and (iii) metal fatigue.

In order to minimize cavitations following steps are appropriate:

Annually inspect the runner and other turbine parts and take remedial measures.
 Operate the machine as per the instruction given by the manufacturers. Mind that the unit should not be run
below certain specified load to avoid cavitation prone zones.
 Cavitations can be effectively controlled at the design stage itself by way of ensuring proper submergence, use
of cavitation resistant material and adoption of optimized runner profile based on model test.
 Vibrations, excessive noise and cavitations are also experienced as a result of draft tube pulsation and surges
at no load or part gate opening. For minimizing the pulsation of the draft tube, the following measures are to be
taken:
 Air admission through air admission/vacuum breaking valve installed at top cover.
 Provision of fins of flow splitter in draft tube to break the vortex flow.
 Provision of a by-pass arrangement for releasing the pressure built-up below the top cover.
Failure of Turbine Guide Bearing
A number of cases of turbine guide bearing failures have come to notice depending upon types of guide bearing
designs (plain water cooled bearing, bath type bearing and grease lubrication bearings). In the case of plain
water cooled bearing, either ferrobestos or rubber lined pads are used against a welded shaft sleeve. The
ferrobestos lined bearings have given considerable trouble at one of the power plants in India and these had to
be replaced by rubber lined pads. Complaints of excessive oil splashing have been recorded about the rotating
bath type bearing, while the grease lubrication bearings have a tendency to clog when in contact with the water
and it is very essential to use grease with the right type of properties.

Shaft Gland Seals

Two types of shaft gland seals (i) carbon or ferrobestos segment (ii) Rubber flap are generally in use. The
maintenance of rubber flap type gland seal is simpler and easier over the carbon or ferrobestos segment. Only
the precaution to be taken during assembly of rubber gland is to see that the jointing of the rubber seal is done in
the proper way. It is, however, to be noted that the quality of rubber used plays a very important role for
satisfactory performance of the rubber gland. The shaft sleeve should also be checked, it should be circular and
smooth and properly secured on the shaft. In case of carbon or ferrobestos segment type of shaft gland seals, the
seal segments are housed in stuffing box, which being always in touch with the shaft is subjected to excessive
wear and tear. The overhauling of the staffing box becomes necessary when it is observed that consumption of
cooling water has considerably increased or excessive water in top cover appears to be
coming. Normally the maintenance of this type of seals is required to be done annually. In the event of breakage
16
or damage to a carbon segment, it is advisable to replace the whole set of carbon segments. In very rare case
only, the damaged segment is replaced. Whenever reassembly of the gland seal with existing gland ring or new
ring is done it is
important to ensure:
 All carbon/ferrobestos segments are carefully examined for any chipping or damage.
 All stainless steel facings are flat and square with the gland sleeve and there are no steps at the facing joints.
 Stainless steel facing and sleeve are completely free from grease.
 Ensure proper bedding of segments with shaft sleeve.
 All segment to segment and segment to stainless steel mating surfaces are perfect.
*All garter springs are assembled to obtain even tension all around.
 Alignment of segments in the lower assembly is carefully checked with a hard wooden peg or similar device
before fitting retaining pins

Guide Vane Servomotor

In the guide vane servomotor, main source of trouble is rubber cup seals, which need to be replaced after a few
years. Normally rubber seals are replaced during capital maintenance. It is important that all the parts are match
marked before dismantling so that reassembly is correctly done.

Routine Maintenance of Hydro-Mechanical Equipment

The major hydro-mechanical equipment to be covered by routine maintenance are Intake Gates, Main Inlet
valves (butterfly and/or spherical) and Draft Tube gates. The following are the periodic inspection and checks
for the preventive maintenance of hydro-mechanical equipment.

Intake Gates
The maintenance of intake gates include (i) cleaning up, (ii) adjustment, (iii) lubrication with recommended
lubricants & methods, (iv) replacement of defective parts, (v) repair of damaged parts, (vi) recoating of
damaged coat on ropes, (vii) recording details of all works carried out with date & time, and (viii) painting of
gates and hoisting arrangement. Following inspection and checks are recommended for routine maintenance of
intake gates:
(a) Daily inspection should be carried out by gate operator to ensure:
 Proper oiling and greasing whenever required;
 Tightening of loosened parts of tightening contacts in electrical system;
 Checking of ropes and hoisting arrangements;
 Checking general condition of gates and gate grooves wheels, etc.
(b) Periodic inspection (half-yearly or annual)
 Dismantle and check all components for any damage;
 Rectify damages or replace worn out irreparable components;
 All safety precautions, e.g., taking proper shut down, installing safety tags, red flags, etc., must be taken, when
any work is being done on gates;
 Before taking up work on gates, stop log gates (duly inspected and repaired) must be lowered in the groove
meant for the same and plug all leakage through them.
(c) Lubrication of gate parts
 Servogem EPI (IOC) or equivalent of other brand.
 Rope drum shaft for all hoisting units (once a month)
 Plumber blocks for all hoisting units fitted with bush bearing (once in two months).
 Coupling for transmission shaft (once in two months)
 Plumber blocks for manual operation (once in three months).
 Servogem -3 (IOC) or equivalent of other brand.
 Spherical roller bearings for gate wheels (once in two months).
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 Compound –D (CAMAX Bharat Petroleum) or equivalent of other brand.
 Lifting ropes (once in six months)
 Servocoat 120 T (IOC) or equivalent of other brand.
 Gears and pinions for all hoisting units (once in two months –Meshing faces only)
 Gears and pinions for manual operation (once in 3 months).
 Gears and pinions for all travel mechanism (once in two months).
 Gears and pinions for position indicators (once in two months).
 Servosystem (320 IOC) or equivalent of other brand.
 WOM reducer for all hoisting units (once in two months).
_____________________________________
Note: All brand name products such as lubricating oil etc., which have been mentioned in the text on this page
and elsewhere in the document are the products used in the NPS power plants and cited for illustration only.
However, it is up to the plant owners to utilize other products best suited to them.

Main Inlet Valves (MIV)

The turbine may have either a butterfly or spherical valve. This valve is used each time the unit is shut down.
Valve seats, seals, operating links, bearings, bushings, power source and hydraulic links are the main primary
concern for maintenance. The valve function should be verified periodically through test or normal frequent
operation.

Butterfly Valves: Butterfly valves generally consist of a disc or lattice mounted on a shaft that
rotates in cylindrical body. Usually, the disc and lattice profile is contoured in the flow direction to provide a
smoothen hydraulic flow and balance forces on the valve. The disc is oriented parallel to the flow to minimize
any restriction when opened and at right angle to the flow to provide full closer. Valve seals are on the
circumference or in contact portion of the valve body. These seals can be replaced or adjusted without removing
the disc from the valve. Valves have flanged connection and spool pieces to facilitate dismantling. Sometime
welded connections are preferred to save cost. The maintenance procedures and frequencies for these valves are
as follows:
 Check operating system daily and ensure it is working smoothly;
 Check for any leakage through joints daily;
 Replace main seals in annual maintenance, if damaged;
 Other seals may be replaced as and when heavy leakage is observed;
 Overhaul operating system annually;
 Replace gaskets in flanged connection during annual overhaul.

Spherical Valves: Spherical valves have a body shaped like hollow sphere with flanges or other connection for
mounting in a piping system. The rotor (shaped like ball) has a cylindrical hole through its centre at right angles
to support shafts located on each side of valve. In open position with rotor opening parallel to the flow
direction, the valve offers and unrestricted flow with minimum disturbance to the flow path. To close the valve,
the valve rotor is turned to 90o from the axis of rotor opening. Spherical valve has tendency to close for
positions less than 50% opening which facilitates under emergency closing. Movable seals reduce valve leakage
when the valve is closed. Mostly the valves have both upstream and downstream seal. The upstream seal is
maintenance seal or emergency seal, the downstream seal is working seal. When valve is closed under full
pressure, the upstream maintenance seal allows replacement or maintenance of the working seal without
dewatering the penstock. The upstream maintenance seals have positive mechanical locking to prevent
accidental opening. The maintenance procedures and frequencies for these valves are as follows:

 Daily checks of operating system and remedial measures are must;

 Annual inspection and overhauling of mechanical seal after dewatering penstock is must;
18
 Annual inspection and overhauling of operating seal is also essential;
 Annual overhauling of operating mechanism to ensure smooth working throughout the year is also done;
 Annual overhauling of the valve rotor and other parts are also taken up as required.

The following checks and attending are also essential during annual maintenance:
 Checking and attending leakage from valve and dismantling joint;
 Check and attending oil leakage from servomotor;
 Checking and attending the setting of Limit Switches & Operation of the same;
 Check and attending the leakage of distributing valve;
 Check the correct working of the pressure gauges. Lubricate the parts, if necessary;
 Checking and attending for leakage in the piping;
 Checking all the MIV system connection & union for tightness;
 Checking all the MIV servo linkage during operation, look for backlash;
 Cleaning of valve body, seal and solenoid valve;
 Checking the actuating solenoids for operation of valve. Cleaning the contacts and rollers;
 Checking the operation of by-pass valve;
 Checking for cracks, pitting and cavitations, etc. of MIV and Servomotor;
 Inspection of rubber seals;
 Checking trunnions & bushes, bolts & nuts, etc.;
 Checking gland packing and lubrication;
 Checking foundation bolts and nuts of valves and servomotor. Cleaning the bolt, nuts etc.
 Checking servomotor piston and its collars & its gland packing;
 Checking hole of the servomotor cylinder;
 Checking the pins and bushes of servomotor & its air valve;
 Checking the operation & closing times of the MIV

Draft Tube Gates

One, two or three bulk head gates are needed to close off the draft tube. These are usually cable
suspended gravity gates and designed for balanced pressure closure. These are usually dropped
to close or lifted to open through hoisting arrange-ment having rope drums. The main problem
with sealing is due to collection of debris at bottom seal area. For withdrawal of gate, equalizing
pressure across the gates is done with by-pass line valve located within gates. When machines
are running, these gates and hoist remain available for maintenance. These should always
remain in perfect condition for use during emergencies for power station. During annual
maintenance of unit, these gates are required to be lowered so that dewatering of draft tube is
possible. As such, maintenance and overhaul of these gates are taken up before starting annual
maintenance of machine. Lubrication of operating mechanism, its electrical system and coating
all ropes meant for lifting are of main concern for maintenance.

Logging and Reporting

Logging
A station log needs to be maintained at each facility in the Control Room. The station log
contains chronological record of all operating and maintenance activities and events which
provides a reference for future use. Operation and maintenance personnel use these information
to evaluate present and past plant status. The station log may be paper, electronic or a
combination of both. The station log documents are following:
 Staff on duty
 Operations of waterway equipment including gates, valves and changes to spillway gate
positions.
 Communications involving plant operations, switching, Hot Line Orders, clearances, special
19
conditions, alarms and relay operations. All communications with Transmission Operators shall
also be logged.
 Water elevations and releases and operational changes affecting water elevations and
releases.
 Status of auxiliary equipment.
 Testing of equipment or gate controls.
 Act of vandalism or other security incidents.
 Requests and occurrence to change from normal operation during an emergency or unusual
conditions.
 Communication network checks and emergency exercises conducted.
 The disabling and re-enabling of facility alarms.
 Unit start and stop times.
 Any equipment failures and malfunctions.
 Line outages.
 Breaker opening and closing.
 Callouts.
 Any change in unit status (available, unavailable, etc.)
 Status of all major equipment.
 Listing of personnel (visitors) arrival and departure.
The plant manager must review and initial the operating Log Book. Shift turnover is critical part
of the facility’s operation and provides oncoming operation staff with an accurate picture of the
overall status of the facility. Hence, the incoming operation staff must review logs, turnover
checklist (if used), SCADA displays, alarm displays, disabled alarms, protective devices, and
computer pages, and they must receive verbal briefing from the on-duty operator prior to
assuming responsibility for the operation of the facility. A visual inspection of control boards
including a test of the annunciator windows will be completed to verify indication/annunciation
light is operational. During a shift turnover, at a minimum, the information on major equipment
status, alarm status, work in progress, hazardous energy control procedures, any abnormal plant
conditions, water release, power schedules and work schedule should be exchanged. The
operation staff, then, will sign into the log documenting that shift turnover has been completed.

Reporting
With the passing of time along with growth of demand in electricity and due to advancement in
the technical development the interconnected power system are becoming more and more
complex. This requires increased emphasis on the analysis of system performance to ensure
achievement of the best reliability. One of the most important requisites for such analysis is the
availability of clear, concise and the accurate reports on power system operation and
maintenance (O & M) for review by management at various levels. Specific details regarding
preparation, issuance, and distribution of the monthly O & M reports is described in the following
paragraph.
A narrative report of power plant O & M activities shall be prepared and distributed monthly by
the power plant O & M office on each project that includes operating power facilities. The report
shall briefly describe all important non-routine events of a power plant O & M nature that
occurred during the month, such as date, time, duration of major items of maintenance
undertaken or accomplished new equipment or service installation or connections, changes in
system arrangement or interconnections with adjacent utilities, major power interchanges
between systems or water movements scheduled or accomplished, new facility (ies) added,
important personnel activities, etc. The report shall be distributed to the concerned as specified
by the system operating authority/ regulating authority as applicable. The format for
the report has been given in Annex –2.
In addition to the above indicated monthly O & M report the following reporting are required for
record keeping for future reference. The typical formats for the reports will be as given in Annex-
3.
20
 Annual Outage Program,
 Annual Availability Declaration,
 Monthly Generation Outage Program,
 Weekly Generation Outage Program,
 Scheduled Outage, Request Form,
 Forced/Maintenance Outage Request Form,
 Monthly Availability Declaration on Hour to Hour Basis,
 Monthly Availability Declaration on Hour to Hour Basis,
 Weekly Availability Declaration,
 Daily Availability Declaration,
 Verbal Dispatch Instruction Confirmation,
 Daily Generation Report Form,
 Daily Generation Log Sheet,
 Fault Registration Form,
 Monthly Generation Performance Report Form,
 Monthly Generation Report Form,
 Monthly Outage and Reduced Output Report,
 Maintenance Outage Report Form,
 Loading Status and Scheduled Outages,
 Forced Outages of Transmission Lines and System Failures, and
 Transmission Line Shutdown Implementation Form.
In case any accident occurs, the accident hazard notice needs to be given as earliest as possible
to the chief electricity inspector appointed by GoN.

21