Role of NCA for Hydrological Forecasting in Narmada Basin | RTDAS In Narmada Basin | Implementation of the project | Technical Profile | Network Configuration | Sensor Details  | Communication Equipments |  Hydromet Subgroup |
 

 


Sensors

1. 'Met One' model 370, tipping bucket type rain gauge with 0.25 mm resolution.
2. 'Met One' model 010C, cup type anemometer, range up to 200 km/hr with 0.1 km/hr resolution.
3. 'Met One' model 020C, potentiometer type weather vane, range 0-360 degree with  0.1 degree resolution.
4. "Vaisala model HMP-45D", Ambient temperature and relative humidity probe, Pt -100 make, range (-) 40 to  (+) 60 degree celcus with resolution of 0.1 degree C and film polymer capacitance for RH with range 0.8 to 100% with resolution of 0.1 %.
5. "Vitel" make, float type water level sensor with optical shaft encoder with 3.75 mm resolution.
6. “Vitel” make pneumatic water level (bubbler) type sensor model VB 2000 at selected sites.
7. "NOVA LYNX" model 3005SS, evaporimeter with water level and NRG-40 wind speed sensors, pan size 25x120cm for continuous measurement.
8. "NOVA LYNX", model 3020 pyranometer, range 0.3 to 3 micron with resolution 1watt/sq.m.

Sensor Details:

Rain gauge:`Met One’ model 370 Tipping bucket rain gauge of 20 cm orifice is an accurate, sensitive and low maintenance sensor to measure rainfall on a continuous basis.  Water does not collect in the sensor, but it drains out each time an interval bucket fills with rain water equivalent of 0.25 mm rainfall and tips.  The other end bucket comes in its place instantaneously any loss of rain water to be accounted.  At the time of tipping, a switch closure pulse is sent to the local Data Collection Platform (DCP) for counting.

Anemometer:`Met One’ model 010C uses a durable, three cup anemometer assembly and solid optical link with a 40 slot chopper disk to produce output whose frequency is proportional to wind speed.

Potentiometer type weather Vane:`Met One’ model 020C weather Vane is a wind direction sensor which uses a light weight Vane and a micro-torque potentiometer to produce an analog voltage output in the range 0 – 5V DC proportional to wind direction.

Ambient temperature and Relative humidity: `Vaisala’ make model HMP-45D probes is designed for the measurement of ambient temperature and relative humidity.  Temperature measurement is based on resistive platinum (Pt 100) sensor as a passive measurement.  For relative humidity measurement a capacitive thin polymer sensor HUMICAP 180 is used.  Both the sensors are located at the tip of the probe duly protected by a membrane filter.

Water Level Sensor:

Float Type Wate Level Sensor: Vitel make model SE512 water level sensor comprises the assembly of SE512 shaft encoder, float, stainless beaded tape, counterweight and pulley.  It necessarily needs stilling well of appropriate range for installation.  The level of water in the water body viz river & reservoir is represented by the level of water in the stilling well. The float and counter weight tied with the separately beaded tape ends are suspended in the stilling well from the pulley.  Pulley is coupled with the encoder shaft.  Float floats over the surface of water in the stilling well.  The circumference of pulley is 375 mm.  As the float rises or falls according to change in water stage in the stilling well, the optical chopper wheels generate quadrature signals resulting in 100 pulses per revolution of the shaft which is registered in the DCP Vx 1004 through SDI port.  The encoder performs all scaling and data conversion for reporting the absolute value in proper engineering units.  There is a local display unit of the engineering absolute value of water level above the OFFSET value.  It also helps to recalibrate the encoder.

Pneumatic water level (Bubbler) sensor: Vitel make pneumatic water level sensor is a software controlled device which measures the light of water column above the orifice head.  The differential pressure needed to bubble out the dry air through the water head measures the height of water column in proportionate manners.  The equipment takes several samples of readings before its averaging.  The surrounding air is passed through filter and dessicators filled with tiny calcium sulphate granules before the entering into the internal compressor.  The compressor compress the air optimumly to 30 to 35 psi which purges through the orifice line at the set rates during reading samples.

Evaporimeter: The evaporimeter model 3003 Novalynx make measures the changing water level.  Evaporation pan is of 250 mm depth & 120 cm dia.  The pan is physically coupled with the Evaporimeter through a 12.5 mm dia pipe without any leakage.  The diameter of the Evaporimeter housing is 203 mm and 700 mm height which also serves as the stilling well.  Evaporimeter comprises of float, a counter weight, a chain attached to both float and counter weight, and a sprocket attached to a precision 1000 ohm potentiometer all mounted in a protective enclosure.  Water inside the evaporimeter represents the water level in the pan.  The float rests on the water surface and it transfers its motion due to change in water level through the chain to the sprocket.  The sprocket, in turn, causes the shaft of the potentiometer to rotate, changing the resistance of the potentiometer and thereby change in the voltage between Zero to 5 VDC.

The output of potentiometer is translated in to the height of water level.  The output of potentiometer is calibrated to give a decreasing voltage as the water level decreases.  The NRG40 wind run sensor provides the information or wind passing over the surface of water in the pan.

Pyranometer: The Novalynx make model 3030 is a star Pyranometer to measure the solar radiation in the spectral range of 0.3 to 3 micrometer.  It measures the temperature differences that are converted into a proportional electromotive force (EMF) through the use of a highly sensitive thermopile.  Sensing of the temperature differences in the solar pyranometer is accomplished by means of a twelve segmental star made of metal plate that has been painted in alternating sections with a special white reflective paint and an absorbing black paint.  Exposed to solar radiation causes the black sections of the star to become more heated then the white sections.  A difference in temperature is created between the black and white sections.  The temperature difference is then sensed by thermocouples that have been embedded directly below the star to generate a voltage with a value of 15 micro volt per square with internal resistance of 35 ohms.  Pyranometer is provided with a dome of optical `SCHOTT’ glass.  A dessicator filled with silica gel granules to absorb the moisture.  The range of equipment is upto 1500 watt per square meter.   

 

Communication Equipments

 


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                Communication Equipment

                • Data Collection Platform
                • Direct Read out INSAT Ground station
                • Solar Power Generating System
                • GPS time code Receiver
                • Antenna
                • Pilot/command Transmitter at MCC

 Data Collection Platform: Vitel make Data Collection Platform (DCP) model Vx 1004 has the same role at Remote stations what a brain has to the human beings.  It is the microprocessor based composite modular unit to perform the tasks of Data Acquisition of the sensed value and its conversion in the engineering value as per its assigned sensor scanning schedules and the limited processing, as well as the `UPLINK’ communication of Data/Text to the Data Relay Transponder (DRT) on board INSAT series Geo stationery satellite, presently KALPANA1 through the helix/planner antenna on the assigned frequency in the DRT band of 402.65 to 402.85 MHz.

Direct Readout Ground station: The vitel INSAT Direct Readout ground station is a Data Acquisition & Monitoring System (DAMS) to demodulate data from a 5 MHz composite frequency (IF) signal.  The system demodulates the IF signals for selected channels and converts the signal into digital message streams which are passed on to the communication controller/INSAT Data Collection System (DCS) computer.   The DAMS also performs signal and data quality measurements on each incoming message and the same are appended to each message as it passes on to the DCS computer.  The DAMS comprise input interface module, multiplexer module.  Besides providing the different DC voltages built on the other modules the IIL provides the IF signal from the INSAT receive system to the demodulator after regulating the regulated signal amplitude through Automatic Gain Control (AGC) circuit.  The multiplexer module converts demodulated digital data from demodulators in to a digital data stream i.e. sent to the DCS computer.  The demodulator module performs the signal processing functions required to receive message/data on a given DCS channel. 

 

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