RAIN GAUGE TIPPING BUCKET TYPE

Transcription

1 RAIN GAUGE TIPPING BUCKET TYPE Approval Date: Version: 2 Purpose The tipping bucket will typically be deployed in remote areas where frequent site visits are not feasible. Conditions and requirements The rain gauge shall be of such a design that it operates reliably and accurately under the prevailing environmental and weather conditions. The rain gauge shall be easy to operate and maintain. The rain gauge shall be supplied with the accessories as needed for effective deployment. All materials on the rain gauge, regardless of the protective layer(s), shall be non-corrosive e.g. galvanised or paint coated iron is not acceptable Sheet material shall not be part of the rain gauge. The bucket design shall be inherently symmetrical, e.g. of moulded thermoplastic material. All materials on the rain gauge that are exposed to sunlight shall be UV radiation resistant. The rain gauge shall be sturdy and shall withstand exposure to extreme climatic conditions. The rain gauge shall withstand attack by fungi, insects, rodents and other small creatures. The rain gauge shall have a smooth and permanent surface finish to minimise evaporation losses. The height of the rain gauge shall be small enough to allow the collector opening to be installed at standardised heights in compliance with Indian and WMO standards. The minimum expected operational lifetime shall be 15 years without loss of functioning. All openings of the rain gauge shall be covered with stainless steel net to protect against any insects entering inside. Appropriate surface treated and corrosion proof mounting bolts (M 6 x 130) with nuts and washers shall be supplied. The data logger shall feature in-built lightning protection. The rain gauge shall have leg adjusters to set the rim horizontally. A certified calibration test document shall be part of the delivery. The set-up of the rain gauge data logger shall be easy and intuitive. Data retrieval from the data logger to a data retrieval unit and/or a PC shall be easy and efficient.

2 The recorded data shall also include an instrument serial number and/or location identification Specifications 1. Tipping bucket base and collector durable and rigid of cast metal, moulded thermoplastic, FRP or equivalent; galvanised iron sheet is not permitted Rim material gun metal / brass / stainless steel or equivalent Collector size close to 200 mm internal diameter. Depth from rim to funnel 175 mm Bucket size Accuracy 0.5 mm equivalent rainfall or better ±2% of rainfall for non-monsoon conditions ±5% of rainfall or better under monsoon conditions 2. Data logger u. Data logger shall automatically collect the observations from attached sensors, process the same and store them into its memory as per the preprogrammed procedure at every 1 hour interval or any other user-defined interval which the user must be able to set. v. Data logger shall be provided with a LCD colour screen for efficient control of the AWS. The screen shall be easily readable under field conditions, with a keypad option and a minimum 2-line backlit LCD display in the front panel with facility to display at least 16 characters per line. w. The number of analog/digital/ SDI channels in the data logger must be compatible to the sensors being supplied. x. It should have at least two built-in high performance analog channels, and two built-in digital channels, at least one RS-232 ports in the form of standard DB9 connector, one USB 2.0 or better port and one SDI -12 port to interface different types of sensors. It should have standard ethernet port. y. The sensor's signal conditioning unit should be an integral part of the data logger. z. Data including the setup and program files shall be transferable from the system via a serial port/usb 2.0 or better port to PC and PCMCIA card or other suitable memory device and vice versa. It should be possible to upload or upgrade the software of the data logger using USB or RS-232 port aa. If specified in the Schedule of Requirements, the data logger should support GSM/GPRS-based and satellite-based technology for transmitting the data. bb. The system shall have provision to easily include and change the following information as mandatory requirements: Unique station identification code Sensor identification.

3 Time of observation cc. Providing necessary electrical power to the sensors and conversion of electrical output signals from the sensors into engineering values based on calibration equations stored in the memory shall be mandatory. Full compatibility with all types of sensors provided in the packages shall be mandatory. dd. Storage of observed data along with time for all the parameters in the memory shall be mandatory. ee. Memory capacity to retain at least one year s data is required. Data shall be available even if the power supply to the system has failed (RAM Backup battery) for one year. ff. The stored data shall be retrievable via serial port/usb 2.0 or better port to a PC/laptop and a PCMCIA card or any other compact and commercially available solid state memory device. gg. The system should be stand-alone and all programming functions/set-ups to be carried out through system keypad and display independent of a PC/Laptop. hh. Setup shall be organized in a tree of menus and sub-menus. Protection of setup parameters and data through password should be supported by the system. ii. Data logger should have a real time operating system. The data logger should have 32 bit or better microprocessor. jj. The data logger should have in-built library or C/Basic language compiler which shall allow the user to create, compile and execute customized programs in the data logger. The library or compiler should support structured and modular programming. The library/compiler shall have in-built functions to take measurement of desired sensors connected to any channel of the data logger at user defined intervals. The library or compiler should have in-built functions to change the properties of all COM ports (RS232 port in the form of standard DB9 connector) such as baud rate, data bits, parity, stop bits, flow control, CTS, DSR, DTR, RTS etc and thus enable the end user to flush required data in desired format to the COM port. All standard baud rates between 300 baud to K baud shall be supported. The data logger should also support recursive execution of a customized program at user defined interval. kk. The data logger should have capability to sample and log the data for specified parameter at user defined intervals in multiple log files. ll. It should have open architecture system to configure any standard commercially available sensor. The system must also support the future up gradation of hardware and software without removing the system from the site. mm. Data including the set-up and configuration files shall be transferable from the logger via a serial port/usb 2.0 or better port to both PC and any commercially available memory device (preferable USB pen drive) and vice versa.

4 Data Logger Specifications ADC Resolution 32 bit or better Conversion Accuracy ± 1 LSB System clock: Stability Long-term 1 ppm/year or better Stability (Temperature) 3 ppm or better from -10 C to 55 C Operating Temperature -10 C to + 55 C range Internal Memory 1 MB RAM minimum Battery Backup (internal) Lithium Battery, storage: 2 years Real-Time Clock GPS synchronized Watchdog Timer System Reset upon microprocessor failure Sample Intervals 1 sec. to 24 hr. in 1 second increments (user selectable) Visual Display 16 Character or more, alphanumeric LED/LCD to operate in temp. range -10 C to +55 C Power consumption Average over an hour shall be less than 0.5 A at 12V D.C. including that of sensors. Power Supply: a) Battery Single 12V 65 AH chargeable maintenance-free capacity battery which shall be capable to run the system for minimum of 30 days during total cloudy conditions. b) Charge controller Internal or External c) Solar panel Rated capacity 30W, Open circuit voltage: 21V, Short circuit current 2.4 A 3. Data retrieval software (DRS) The DRS software shall support functions for conversion of the collected data into ASCII (text) tables, and for efficient visualisation of the time series in tabular and graphical form. Graphical axes shall be generated automatically and be manually adjustable. Units along the axes shall not be awkward but intuitive and easily understandable. All axes shall have sufficient graduation. The labels along the time axis shall be in sensible time intervals, i.e. hh:mm for relatively short periods and dates, e.g.: DD/MM/YYYY, for long periods. The same applies for the level axis. The unit-labels shall not cover each other. To enhance readability, adequate gridlines, both along time and level axes, shall be generated automatically by the graphics functions, approximately 5 gridlines per axis. The gridlines shall also be user adjustable. The user interface shall support efficient functions to select and visualise subsets of the time series, e.g. a single day or several days somewhere out

5 of many weeks of data. Efficient window functions shall be available to visualise the data in the required resolution, i.e. the level scale shall be user adjustable. Software that can only display sample counts or total duration or does not support axis and grid adjustment is not permitted. DRS software shall support error free transfer of the retrieved data to a PC. Note that in particular, the graphics capabilities are a major reason to apply a palmtop or Laptop computer as DRS. 4. PC Software PC software shall be part of the delivery and will be used in the office, e.g. on a desktop PC. The PC software shall efficiently and reliably transfer the collected data from the DRS to a PC environment. The PC software shall have functions for conversion of the collected data into ASCII (text) tables. The tabular data will be imported by other software packages, e.g. for analysis and presentation in a spreadsheet and for storage in a database. The PC software shall support the same and more tabular and graphical presentation functions as specified under DRS software. Civil works Civil works will be finalised in collaboration with the supplier.