Field Performance Evaluation of Hydro Power Stations - Department of Hydro and Renewable Energy,Indian Institute of Technology Roorkee
Field Performance Evaluation of Hydro Power Stations


Field Performance Evaluation of Hydro Power Stations

Field Performance Evaluation of Hydro Power Stations Brochure

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Scope of Testing
  • Visual Inspection
  • Functional Checks
  • Measurements and Tests
  • Developed capability to carry out Field performance/efficiency testing as per IEC 60041:1991, IEC 62006:2010 and AHEC-IITR: OCT.2012.
  • Performance evaluation/ efficiency test of over 240 hydropower plants of various capacities in different terrain and states have been carried out .
  • Various methods applied for discharge measurement and head measurement.
  • Providing technical consultancy and efficiency testing of pump/turbine.

Visual Inspection

  • General inspection
  • Inspection of civil works (diversion, water conductor system, power house and tailrace)
  • Inspection of electrical equipment (control panels, power transformers etc.)
  • Inspection of mechanical equipment (turbine, governor system, cooling system)

Measurements and Tests

  • Unit Efficiency Test
  • Error Test on Measuring Instruments
  • Operational Tests on Protective Relays
  • Vibration Measurements
  • Sound Level Measurements
  • Load Rejection Test
  • Maximum Power Output Test

Functional Checks

Verification the operation functioning of the components subsystems and shortcomings defects, if any, are recorded.

  • Control Panels: Functional checks on external accessories (lamps, push buttons, switches, digital indicators, buzzers, hooters etc.) and internal accessories (panel lights, panel light switches, space heaters, thermostats etc.).
  • Fault / Status Annunciators: Component check, test, accept and reset functions.
  • Circuit Breakers: Trip and close functions.
  • Master / Trip / Auxiliary Relays: Operate and reset functions.
  • Control / Regulating Devices: Flow / head regulating devices, excitation voltage control, speed governor control, power factor control,, manual start / stop operations, manual / auto synchronization, local / remote control of transformer tap changer, etc

Methods of Unit Efficiency Measurement by Discharge Head Method

  • Absolute value of the discharge through the turbine.
  • Net water head available at the turbine, and
  • Electrical power output of the machine.
  • Uncertainty in the measurement by this method is ±2% to ±4% depends on type of instrument used.


Absolute Discharge

  • Current-meter method (Uncertainty ±2.5%)
    • PCM mounting frame could be installed at intake channel, tailrace channel, Intake duct for discharge measurement.
    • Point velocities of measurement section are recorded.
    • Discharge is calculated by velocity area integration method.
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Acoustic Method for Discharge Measurement
  • Clamp-on Transit Time flow-meter (Uncertainty ±2.5% to ±3.5%)
  • Intrusive Type transit flow meter (Uncertainty ±1% to ±2%)
  • Ultrasonic sensors are clamped outside/ inserted (intrusive type) of the penstock.
  • Mounting of sensor depends on the diameter of penstock.
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Acoustic Doppler Current Profiler (Uncertainty ±1.5% - ±3%)

  • ADCP transmit and receive Acoustic signals. Sound waves scattered back from particles within the water column.
  • The frequency shift of the echo is proportional to the water velocity along the acoustic path.
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Measurement of Net Head

  • Measurement of net head requires measurement of total head at the inlet and that at the outlet, respectively, of the turbine and using their difference.

Head Measurement in Pressure Channels (Uncertainty ±0.5%)

  • Electronic pressure gauge is connected to the pressure manifold which is required to fabricate as per IEC 60041:1991 at intake of turbine.
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Free Water-Surface-Level Measurement in Open Channels (Uncertainty ±0.5% )

  • Free water surface is measured separately near the intake point and the opening of the draft tube from ultrasonic level sensors (ULS).
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Measurement of Electrical Power Output (Uncertainty ±1%)

  • A reference digital wattmeter with an accuracy class of 0.2 or better is connected in parallel with the panel wattmeter of the generator.
  • A test terminal block (TTB) or sliding-link type terminals, if provided in the metering panel, would facilitate connecting the reference wattmeter without shutting down the machine.
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  • The electrical power output of the generator is calculated by multiplying the reference wattmeter reading with CT ratio and VT ratio.


Vibration Measurements (Uncertainty ±5%)

  • Vibrations measured at each bearing of the generating units on no-load condition.
  • Both rms displacement and rms velocity of the vibrations in the frequency band of the 1 Hz to 1 kHz are measured.
  • Measurement is done at four mutually perpendicular locations on the bearing, and both along axial and radial directions.
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Sound Level Measurement (Uncertainty ±1.5 dB)   Load Rejection Test
  • Sound level measured in "weighting factor A" mode near the machines at no-load conditions.
  • Readings are taken 1 m away from the surface of generator, turbine, flywheel and gear box (as applicable) at right angle to the machine shaft, both on upstream and downstream sides of the machine.
  • The generating unit under test is initially loaded to its rated value and its speed is noted down.
  • The maximum sound level near the machine is also recorded on the basis of sound level test.
  • The load on the machine is then suddenly rejected using the emergency shutdown push-button switch and the peak values of the speed and sound level (at the same point) attained consequently are noted.
  • The maximum rise in the speed is compared with run-away speed of the generator as specified by its manufacturer.


Maximum Power Output Test (Uncertainty ±1%)

  • Test conducted to check whether the maximum electrical power output actually available from the generating unit matches with the value specified by the manufacturer.
  • Test conducted at the rated head or at the head / discharge specified for maximum output of the generating unit.


Turbine Efficiency Measurement by Thermodynamic Method (Uncertainty ±1%)

  • In the case of SHP stations of high heads (100 m and above), the hydraulic efficiency of the turbine can be measured by thermodynamic method.
  • It involves accurate measurement of the small temperature rise of water that takes place between intake and outlet of the turbine due to losses from inlet to outlet. Pressure measurement is also conducted to determine head, but discharge is not required being one of the major advantage of this method.
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  • The overall efficiency of the generating unit is determined by assessing the hydraulic & mechanical losses in the turbine and in its auxiliaries and all losses including electrical and mechanical in the generator.
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  • Thus the method is suitable when the efficiency of the turbine alone is required and not the complete generating unit. Thermodynamic method has lesser uncertainty as compared to efficiency measured by any other discharge measurement method.

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Instrument Used For Field Performance Evaluation of Hydro Power Plants

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Three Phase Power Analyzer

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Single Phase Power Analyzer

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Ultrasonic Transit Time Flowmeter - Clamp On

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Ultrasonic Transit Time Flowmeter - Clamp On

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Ultrasonic Transit Time Flowmeter - Clamp On

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Ultrasonic Transit Time Flowmeter - Intrusive Type

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Ultrasonic Transducer - Intrusive Type

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Ultrasonic Transducer - Intrusive Type

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Ultrasonic Flat Transducer - Intrusive Type

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Propeller Current Meter

Propeller_Current_meter.jpg (23 KB)

Propeller Current Meter

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Area Velocity Flowmeter

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Ultrasonic Level Sensor

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Pressure Transmitter

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Submersible Pressure Transducer

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Pressure Calibrator

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Vibration Meter

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Sound Level Meter

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Infrared_temp_gun.jpg (33 KB)

Temperature Sensor

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Thickness Gauge

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Underground Pipe Leakage Detector

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Total Station

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Relay Tester


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  • Performance evaluation / efficiency test of over 240 hydropower stations of different capacities in different terrain and states using different methods of discharge measurement and head measurement.


Time Line for Testing

Details about Hydro Power Stations from Owner   03-04 days
Data will be reviewed and suggested method   05-07 days
Pre test visit if required   01-02 days
Advise for Provision to be made at site for testing   15-20 days
Testing at Project   02-05 days
Report   10-15 days


Papers published in Research Journals

  • Arun Kumar, R.P.Saini, B.K.Gandhi, R.K.Srivastava, Pradeep Chandra and A.K. Dubey Experiences in Discharge Measurements at Small Hydropower Stations in India, , Flow Measurement and Instrumentation 69 (2019) .
  • Rahul K. Srivastava, Arun Kumar, B.K.Gandhi and R.P.Saini Experience with Ultrasonic Transit Time Flow Meter for Hydro Power Plant Efficincy Measurement, IGHEM 2018.
  • Arun Kumar, R P Saini and B K Gandhi Comparative Discharge Measurement in Small Hydro Power Plant using different Methods, Pradeep Chandra, IGHEM 2018.
  • Arun Kumar, B.K. Gandhi, and Pradeep Chandra Experience of Vibration and Noise Measurement of Small Hydro Power Plants, IGHEM 2016.
  • B.K. Gandhi, Arun Kumar and Rahul Kumar Srivastava Discharge Measurement Through Multiple Gates of Low Head Power Plants Under Unfavorable Conditions, IGHEM 2016.
  • B.K. Gandhi, Arun Kumar and H.K. Verma Discharge and Efficiency Measurement in Bassi Hydro Power Station in India, IGHEM 2014.
  • Shantaram.S. Patil, H.K.Verma and Arun Kumar Efficiency Measurement of Hydro Machine by Thermodynamic Method, IGHEM 2010.
  • B.K. Gandhi, H.K. Verma and S.S. Patnaik, Discharge Measurement in Small Hydropower Stations Using Acoustic Doppler Current Profiler, IGHEM 2008.
  • Verma, H.K. and Kumar Arun, "Instrument Networking for Efficiency Measurement in Small Hydro Power Stations", International Conference on Advances in Hydraulic Efficiency Measurements at Lucern, Switzerland, July 14-16, 2004.


  Professor in Charge
  Prof Arun Kumar

Area of expertise:
  • Vast experience in the field of hydro power engineering

Phone : Off.(+91 1332) 286134, 286135, 285821
E-mail :,

arun_kumar.jpg (10 KB)
  Prof R P Saini

Area of expertise:
  • Hydro Turbine Design and Performance Testing
  • Silt Erosion in Hydro Turbines
  • Optimal Selection of SHP Equipment

Phone : Off.(+91 1332) 285841
E-mail :,

  Research Staff
  Rahul Kumar Srivastava
Research Associate

Mob No. 9430065527
E-mail :

Rahul Kumar Srivastava.jpg (17 KB)
  Pradeep Chandra
Project Associate

Mob No. 9639749741
E-mail :

Pradeep Chandra.jpg (8 KB)
  Ankit Kumar Dubey
Project Associate

Mob No. 9411720540
E-mail :

Ankit Kumar Dubey.jpg (25 KB)
  Navin Kumar
Project Assistant

Mob No. 9917261107
E-mail :

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11a.jpg (24 KB) Instrumentaion Laboratory,
Department of Hydro and Renewable Energy,
Indian Institute of Technology Roorkee,
Roorkee-247 667
Uttarakhand, India
Tel : +91-1332-285821, 285841, 286437


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