Electronic Milk Tester by Reil

This is a study made during training at the organization. The source of write up is company and internet. I hereby do not take any disclaim of content of matter. It should be used for reference and study purpose only. Introduction Rajasthan Electronics & Instruments Ltd. was founded to aid in the upliftment of the rural masses by enpowering them, making them self-reliant and upgrading their living conditions by taking electronics to the villages. Rajasthan Electronics & Instruments Ltd. (REIL) has a prominent place amongst the electronics industry of Rajasthan.

The company is a joint venture between the Government of India & the Government of Rajasthan, through their respective institutions. The company was conferred the status of a “MINI RATNA” by the Department of Public Enterprises, Ministry of Industry, Government of India in 1997. It has been certified as an ISO 9001 firm w. e. f. The area of business extends to manufacturing and marketing of electronic products/ services in the following areas: [pic]  Agro-Dairy Sector [pic]  Solar Photovoltaic Sector [pic]  Industrial Electronics Sector pic]  Information Technology REIL has its registered office & Manufacturing facilities situated in Jaipur. Other offices include the corporate office within the city and Field maintenance centers (FMCs) and Sub-FMC’s spread over most of the regions of the country. The birth of cooperative movement in India has its roots in the vision of Dr. Verghese Kurein, ex-Chairman, NDDB. He realized that the upliftment of marginal dairy farmers lay in their own hands through cooperative movement at community level. NDDB, along with Department of Electronics, Govt. f India conceived a project to introduce Electronic Milk Testers (EMT), for accurate and instant display of fat content in milk. The technology was arranged in collaboration with Danish Organization M/s. N Foss Electric, and thus Rajasthan Electronics & Instruments Limited was born in 1981. Encouraged by the success of the EMT and the willingness of the rural folk to accept modern technology, REIL initiated a bold step of providing a paradigm shift in technology by introducing computers at village level. It also made forays into the Renewable Energy Sector as well as Industrial Electronics and IT and has never looked back since.

With the advent of Solar Photovoltaic technology in the country and looking to its prospective applications for the rural areas, the company ventured into this segment, initially to manufacture SPV Modules in 1985. In the field of SPV technology the company further diversified into the manufacture of Solar Photovoltaic based application products, sub-systems and integrated systems most of which were developed in-house. In the SPV segment, the Company manufactures SPV modules and application systems including Domestic Lighting System, Street Lighting System, and Chargeable Power Packs for the rural, telecom, Railway and Defense sectors.

The company has a strong in-house Govt. recognized Research & Development Division which has enabled the company to effect considerable improvements in the initial adopted technologies. Indigenization of the Milk Testing equipment and incorporating the latest State-of-the-Art microprocessor designs over the initial and older LSI designs has enabled more features and new add-on equipment has been developed to provide integrated system solutions.

A prestigious collaboration with the Department of Electronics (DoE ) in 1990 for the establishment of Rural Electronics Technology Centre and an award from DoE for Excellence in Electronics in 1991, testify REIL’s achievements in the field of Rural Electronics. The Consistency in Excellence is recognized with repeated award for Excellence in Electronics for the year 2001, given by the Ministry of Communication and Information Technology The Company has an authorized capital of Rs. 150 Lacs (US$ 0. 33 million approx. ) and a paid-up capital of Rs 125 Lacs (US$ 0. 7 million approx. ). The Company has recorded a turnover of Rs. 59. 88 Crores (US$ 13. 30 Million approx. ) for the financial year ended 31st March, 2005 Agro Electronics Division The Electronics Division kicked off its operations in 1982, –the year of formation of the Company — and has notched up many credits in the last one and a half-decade. The operations started with the Electronic Milk Tester, under technical collaboration with A/S Foss Electric of Denmark, and assembly of Electronic Milk Tester (EMT) in SKD form, from kits supplied by the collaborator, initially.

The Company has rapidly absorbed and assimilated the technology, successfully indigenized the product, and in response to customer requirements, designed it on micro-controller technology to suit the needs of the Indian customers. Thus, the auto-zero EMT was introduced in the market in the year 1990. The Company has also successfully integrated the products into a more versatile system, developed in-house through it own development efforts, called the Milk Collection Station. MANUFACTURING INFRASTRUCTURE: The Company has a state-of-art manufacturing facility at its works, for electronic products.

The plant is equipped with modern equipment including component preprocessing systems, automatic & semi-automatic component insertion machines, Wave Soldering machine, Automatic Cleaning System, Advanced Testing equipment, Fault locators, Digital Storage Oscilloscopes, Soldering/De-Soldering Stations. In order to maintain appropriate temperature levels, clean conditions and uninterrupted power supply, the plant is equipped with centralized Air conditioning systems, air shower and over 500 KVA of DG capacity installed at the premises.

The department is also equipped with facility for undertaking manufacturing of products under anti-static environment. [pic] QUALITY ASSURANCE: The manufacturing facility is complemented by the Quality Assurance department equipped with a wide range of test and measuring equipment including IC testers, LCR bridges, digital storage oscilloscopes frequency projector stereoscopic microscope, 3-D Co-Ordinates measuring machine, product life testing machines and environment chamber.

Quality Assurance Group is also equipped with test & measurement facility for Rural Automatic Exchange sub-assemblies, used in communication sector. Renewable Energy Division The Company entered into the Solar Photovoltaic industry in 1985. It started its operations by setting up a manufacturing facility for SPV modules and has expanded its area of operations through manufacture of Balance of Systems for a large number of applications, utilizing its electronics product manufacturing facility.

The Company products are a result of its own in-house development efforts. The Company has a capacity of 2 MW per year on single shift basis. MANUFACTURING INFRASTRUCTURE: |The Company has a capacity to manufacture over 2MW peak |[pic] | |capacity modules/year in a single shift with the flexibility | | |of round the clock operations.

The manufacturing department | | |has machines including string layout machines, module | | |laminators and soldering systems for producing modules | | |conforming to International standards. | | .QUALITY ASSURANCE:

Quality is the keyword in the management philosophy of REIL and tests and checks are carried out at various stages beginning from the stage of incoming raw material to the shipment of the finished product. The Quality Assurance department is fortified with various test equipment including Manual/Automatic cell sorters, Sun Simulator, High Voltage protection testers, Environment Chamber to ensure Quality of highest standard, so that the product can stand up to the rigors of any harsh environmental conditions [pic] PRODUCT DEPLOYMENT: Agro Dairy products: |S. No. Product |Quantity | |1 |Electronic Milk Tester (EMT) |56,668 | |2 |Data Processor based EMT |756 | |3 |PC based Milk Collection Station |3217 | |4 |DP based Milk Collection Station |1631 | |5 |Milko Scan |57 | |6 |Raw Milk Reception Dock Network Automation System |49 | |7 |Raw Milk Reception Dock Operation  Automation System |10 | |8 |SNF Tester |5 | |9 |Electronic Weighing System 500 Kg |76 | Solar Photo Voltaic (SPV) products: |TOTAL SPV CAPACITY PRODUCED |7. 5 MW | |S. No. Product |Quantity | |1 |SPV Pack for MARR system |9704 | |2 |Street Lighting System |10786 | |3 |SPV Lanterns |21456 | |4 |Adult Education Lighting System |686 | |5 |Community TV systems |419 | |6 |SPV Syetems for Railways |383 | |7 SPV Dusk dawn system |1946 | |8 |SPV Packs for village electrification |1831 | |9 |SPV water pumping system |231 | |10 |SPV Packs for Microwave repeater system |16 | |11 |SPV system for petrol pumps |6 | |12 |SPV system for cathodic protection |2 | |13 |SPV Grid interactive power plant-50Kwp |1 | |14 |SPV Grid interactive power plant-25Kwp |4 | |15 |SPV Grid interactive power plant-20Kwp |1 | |16 |SPV Grid interactive power plant-10Kwp |63 | |17 |SPV Stand-alone power plant-1 to 6 Kwp |40 | |18 |Solar Wind Hybrid Power Plant |2 | |19 |Village Electrification | |19. 1 |No. of Villages covered |1774 | |19. |Total SPV generating capacity installed |2121 KW | |19. 3 |Domestic Lighting System |65013 | |19. 4 |Street Lighting System |1105 | |19. 5 |Community TV & Lighting System |105 | |19. 6 |Water Pumping System |37 | |19. |PHC Lighting System |3 | |20 |Indian Railways | |20. 1 |Railway signaling system – At Abu Road, Ajmer, Bandikui, Beawar, Gandhidham, Goramghat, |273 | | |Jaipur, Jalgaon, Kota, Udhna sections | | |20. 2 |Battery charging system – At Ankleshwar, Bandikui, Gandhidham, Jaipur, Marwar, Nadiad, |110 | | |Phulera, Rewari sections | | Information Technology products: |S. No. Product | |1 |Electoral Photo Identity Card preparation Software for Harayana | |2 |Electoral Photo Identity Cards for Gujarat | |3 |GIST cards, Computer Hardware and peripherals | |4 |Smart Attendance System for DAR&PG | |5 |Loan Accounts portfolio Management software for RIICO | |6 |Inventory management & Complaint handling system for LGB | |7 |CPF maintenance system LokCPF for LJP | |8 |Enterprise Resource Planning for Dairies | |9 |Electronic Ticketing Machines for Roadways | |10 |Electronic Parking Machines | |11 |Spot Billing Systems for Electricity Boards | |12 |Interactive Voice Response System (IVRS) | |13 |Veterinary Services Terminal (VST) for Dairies | |14 |Milk Delivery terminals (MDT) for Dairies | |15 |Vehicle Tracking System for Logistic services | |16 |Mobile Recovery Terminals for PACS | |17 |Traffic Offense Recording System for Traffic police | Industrial Electronics products: |S. No. Product |Quantity | |1 |Single Phase Electronic Energy Meter |85,164 | |2 |Three Phase Electronic Energy Meter |5,000 | |3 |Pre-paid Electronic Energy Meters |25 | ELECTRONIC MILK TESTER INTRODUCTION: ? Basic objective in the dairy development programme is to increase the production of mil. Milk collection depends on prompt payment of fair and correct price to encourage producers to increase milk production. The system of payment based on quality (i. e. at content) discourages adulteration and encourages producers to increase production of high quality milk. It is further very necessary that each sample of milk should be tested for its quality and testing should be completed within 2 to 3 hours time in order to make correct payment. Milk sample would also get spoiled if not tested immediately, in the absence of facility to preserve them, specially at village level. ? Age-old traditional ‘GERBER’ method of testing milk by chemicals has many inherent drawbacks, such as human error, multisteo method, handing of corrosive chemical and different types of glassware. All these add to the cost andtime of milk testing.

A quicker, reliable and economical method of milk fat testing has therefore become inevitable and an immediate probem to solve. In the light of some problems faced by ‘gerber’ method of testing, it was felt prudent, to evolve a system which should solve these problems. ? ELECTRONIC MILK TESTER(EMT) is a simple, economical but accurate milk fat testing instrument. It measures the fat content instantaneously on a digital readout. It does not involve the use of corrosive chemicals. It works on light scattering principle with manual homogenization. It operates on AC mains as well as on battery with inbuilt battery charger and automatic switch over to battery in case of a power failure. This technical report of electronic milk tester highlights the following aspects: Basic principle involved ? Diluents preparation ? Key to controls and connection ? Installation ? Operating instructions ? Calibration ? Fault location TECHNICAL SPECIFICATIONS: Measuring range:0-13% fat Capacity:120-150 sample per hour Accuracy (sd):0-5% fat: 0. 06% 5-8% fat: 0. 10% 8-13%fat: 0. 20% Repeatability (sp):0-5% fat: 0. 03% 5-8% fat: 0. 04% 8-13% fat: 0. 08% Sample volume:0. 5ml. /test Diluent volume:6. 5ml. /test Caliberation :one calibration channel, adjustable independently within the range 0-13% Power supply :AC: 220/240v DC: 12v, motor car battery Ambient temp. :5-450C Dimension : 23*31*53 cm.

Weight :16 kg. (without diluents) PRINCIPLE OF MEASUREMENT: ? Electronic milk tester is based on photometric measurement of light scattered by the milk sample. The light is scattered by the flat globules, acting as small prisms. ? Not only flat globules in the milk contribute to the light scattering, but also the proteins may affect the measurement. To eliminate their influence, it is necessary to dissolve this. EDTA solution is used for this purpose. ? All the flat globules do not have the same size. The measuring system requires a constant globule size to provide a mixed relation between the amount of light scattered to the fat content.

The range of globule size is limited in the milk tester to a very narrow region outside the natural range. This is achieved by homogenizing and bringing the globules size into the range of 0. 5 to 1. 5 microns. ? Light rays from a photolamp passed through a layer of fluid in the cuvette and are scattered according to the size of fat globules in the sample. More the fat present in the cuvette, more is the light scattered and less light passes through the cuvette. The rays that do pass through the cuvette strike a photocell, producing a current proportional to light intensity. The current is fed to a digital readout unit which gives direct fat percentage readout. For better understanding of principle of measurement, photometer and its associated parts ar described below: 1) PHOTOMETER: The photometer consists of a lamp, lamp housing and detector assembly. The detector assembly includes the cuvette and photocell. 2) CUVETTE: It is made of two hardened glass discs. One has a ground depression of 0. 4mm the other has two small holes to provide inlet and outlet to the cuvette. 3) PHOTOCELL: It is a selenium barrier/ silicon detector photocell. Care should be taken not to expose this photocell to light when not in operation. 4) LAMP: 12 volts tungsten lamp PREPARATION OF DILUENT: ? Diluent is used to dilute the milk sample and dissolve the proteins. Chemicals required to prepare 10 litres of diluent are as follows: EDTA sachet52. 6 gms EDTA powder-45gm + di-sodium hydroxide-7. 6gm triton-x-1000. 5ml(10 drops) (emulsifier) Anti-foam0. 5ml(10 drops) ? PROCEDURE: Take a clean 10 liter plastic container and add one liter clean water. Add contents of EDTA sachet, containing diluent powder for 10 liters solution. Add 0. 5 ml (10 drops) of triton-x-100 and 0. 5 ml (10 drops) antifoam. Put the lid on the container and shake it until all the chemicals are dissolved, then add 9 liters clean water to prepare 10 litres solution and shake again to mix the solution. ? The ph of this solution should be between 9. 5 to 10. 1. iluent will remain good for 2 weeks before the antifoam becomes inactive. Diluent can be kept longer if antifoam is added to the solution from time to time (0. 5 ml for every 2 weeks) INSTALLATION: ? Place of installation should be such that there should be sufficient space for diluent container and battery also handle of EMT must be easy to reach. ? Check 1Amp. fuse is the mains fuse holder and 10 Amp. fuse is the battery fuse holder. ? Connect power cable on mains. ? Use only 12V motor car battery. Connect red lead of battery cable to ‘+’ pole of battery and black lead to ‘– ‘ pole. Connect other end of the cable of electronic milk tester. Set the select button to switch at LINE/ battery and mains switch at NO. power will now be supplied to EMT from battery. As battery will still be able to supply enough current for several hours of operation. Set the selector switch at LINE, if for any reason, the EMT is to be operated on the mains current without a battery. ? Prepare the diluent in the container as described earlier in chapter 5. ? Connect one end of plastic thick pipe to the INLET stub at the back of EMT and attach the filter unit to the other end which is then placed in diluent container. ? Connect one end plastic thin pipe to the OUTLET stub and place the other end in the waste container. Place empty beaker under milk intake tub and push ‘MILK IN’ and ‘MIX OUT’ buttons alternately until no bubbles are seen in the syringes. End by pushing ‘MIX OUT’ button. PREPARATION OF MILK SAMPLES: ? Sampling: The samples measured should be taken from milk in good condition, i. e. the milk should not have started to curdle or separate, and it should be free of dirt. Since milk fat is of lower density than other milk constituents it tends to rise to the surface. Gently stir the bulk milk just before sampling to make sure that the sample is true representative of the bulk. Fresh unpreserved samples must be sampled immediately. Just before sampling, turn the sample upside down a few times to mix it properly. ? Preservation

If measurement cannot be made immediately after sampling, then sample can be preserved maximum for 12 hours, without refrigeration, by adding 1 ml saturated potassium dichromate solution in 100 ml milk. If they are to be kept longer for measurement and if transportation is necessary, then cool the preserved sample to 5-10o C but never freeze them. Samples which have been cooled will be easy to mix if they are warmed up to 30-40o C before being measured. OPERATION ? Warm-up : If the instrument has been switched-off, then it must be allowed to warm-up before starting measurement. This is done by switching on the EMT half an hour to one hour before measurement. ? De-airings syringes : The flow system must be free of air bubbles to ensure proper measurement. Presence of any air bubble in the syringes must be removed as follows:

Place an empty mix beaker under milk intake tube and push ‘MILK IN’ and ‘MIX OUT’ buttons alternately until no air bubbles are seen in the syringes. End by pushing ‘MIX OUT’ button. ? Zero check : The ZERO setting button is used to set the readout to 0. 00 when the cuvette contains pure diluents and mirror showing below . 40. Press REPEAT button to get second decimal on the display. Place the clean, empty mix beaker under the milk intake tube and press ‘MILK IN’ and ‘MIX OUT’ buttons twice alternately to fill the mix beaker with diluent. Move the mix beaker to the mix intake tube and operate the handle six times up and down. Push the zero button to set the readout to . 00. after zero setting, press the REPEAT button to get one decimal readout. Measurement:

After Dearing and zero setting, measurement can begin. First result after zero check/zero setting should not be recorded as it will be little low. Therefore, measure the first sample after zero check twice and record any second result. Turn the milk sample gently upside down a few times. Place the sample under milk intake and fully press ‘MILK IN’ button. Slowly remove the sample without touching the milk intake tube. Place clean mix beaker under milk intake so that fits into the notch on the side of the EMT. Press ‘MIX OUT’ button in all the way to dispense milk and diluent it to the beaker. Move the mix beaker to the mix intake tube and position it so, that it rests in the notch.

Operate the homogenizer handle up and down three times in a steady measurement. When the handle is pressed down the third time, let it rest in bottom position and result will soon appear on the display. Empty the mix beaker completely and it is ready for the next sample. End of measurement : Place a clean, empty mix beaker under milk intake tube and press ‘MILK IN’ and ‘MIX OUT’ buttons twice alternately to fill mix beaker with diluent. Place the mix beaker under mix intake and operate the handle up and down six times to flush the cuvette. Switch off the EMT. Deairing the homogenizer : Air will enter the homogenizer if the handle is raised when there is no liquid present at the mix intake tube.

Place the mix beaker under milk intake tube and press ‘MILK IN’ and ‘MIX OUT’ buttons twice to fill the beaker with diluent. Now place the filled mix beaker under the ‘MIX INTAKE’ tube and raise the handle. Loosen the blader screw on top of milk intake valve. Let the handle drop by its own weight and tighten the blader screw again. Operate the handle three more times up and down to be sure that all air is out of the system REPEATABILITY: A check for repeatability is a simple way of making sure that the instrument is in proper working order, as leaks and poor connections will affect the repeatability. Take a large, well mixed sample and measure it repeatedly. Press the REPEAT button to set two decimal places on display. Note down the results and make-up table . alculate average result for the obtained readings. Compare each result to average and note difference. The difference for any result should not be more than the prescribed limits. CALIBRATION : The purpose of calibration is to adjust the instrument to give results over the whole measuring range. There are 2 steps in calibration, one to give a correct linearity and the other to give correct results when compared with the results of a reference method. If the milk samples of different fat content are measured, one expects the instrument to show these results within some small limit. If all results are too high or too low by the same proportion the linearity is all right.

Then test the known high fat reference sample on EMT and turn appropriate ‘ADJUST’ screw until correct value appears on display. If high fat results are too low and low fat results are too high or vice versa then linearity must be adjusted as follows: Take one sample of high fat content A= average result of half value B= average result of full value B-2A = C Cx-3 = D From B, adjust with CURVE screw up or down by D, then adjust with ADJUST screw down or up to give 2A. Full value : measure the sample in a normal way to get full value of measurement. Half value : place empty mix beaker under milk intake and press ‘MILK IN’ and ‘MIX OUT’ buttons to fill the mix beaker (i)Place milk sample under milk intake tube and press ‘MILK IN’ button.

Place mix beaker under mix intake tube and press ‘MIX OUT’ button to dispense milk and diluent into the mix beaker (i) Remove this mix beaker and place mix beaker (i), containing only diluent, under milk intake tube and press ‘MILK IN’ button and remove this mix beaker. Place the mix beaker(ii) once more under milk intake tube and press ‘MIX OUT’ button. This will give double volume of diluent, so that result should be half of that obtained in the normal way. USEFUL HINTS ON OPERATION OF EMT: ? The instrument should be kept clean. ? Half an hour to one hour warm up, deairing syringes and zero check must not be forgotten before starting the measurement. When pressing the ‘MILK IN’ and ‘MIX OUT’ buttons, use the ridge on the cabinet to support the fingers, and press the buttons, in, evenly with the thumb. This will improve your instrument’s performance. ? Chemicals must be stored in a clean and dry place. ? It is not necessary to clean the milk intake tube and mix intake tube between each sample instrument. If the milk intake tube reaches far into the sample, it may be necessary to wipe it between sampling and dispensing to avoid carry over. This happens if milk from one sample is left on the outside of the milk intake tube and is then mixed with the next sample. ? Place milk sample under the milk intake tube so that the tip of the tube is approximately 5mm below, the surface.

Though 5mm is not so critical but the tube should be dipped at the same distance below the surface in every sample. ? During storms with lightening, unplug the EMT from mains supply to avoid danger of damage to the instrument. ? EMT should be preferably be connected with battery and normal position of operation is: mains at ON and selector switch at LINE/BATTERY. If mains fails, battery will still be able to supply enough current for several hours of operation. If battery reserve is low, then set selector switch at CHARGE, with mains at ON. This switches off power supply to measuring circuit. A completely drained battery will be fully charged in 8-12 hours. Battery fuse will blow if leads are connected to wrong poles on the battery. ? Check the acid level of the battery once a fortnight and refill it if necessary with distilled water until plates are just covered PC[pic] BASED MILK COLLECTION STATION PC based Milk Collection Station is a specially designed integrated unit, which is a combination of several units viz; the AZ Electronic Milk Tester, Milk Weighing System & Personal Computer with 80 column printer. It measures the weight, fat content and gives the printout of payment slip to the supplier of milk in each shift. The system also facilitates storing ten days/monthly/yearly data and printing of cumulative summary of shift as and when needed.

This state of art equipment is able to perform120-150 operation in an hour. The sequence of operation requires pouring of milk in a weighing container, collection of milk sample at the time of pouring, entering the member’s code through keyboard, measuring of fat content, calculation of payment and printout of slips. FEATURES: Instant measurement of milk fat ? Centralized testing & payment ? Instant measurement of milk weight ? Test 120-150 milk operation in an hour ? Printout of shift end/ten days/monthly/yearly summary ? Instant calculation of amount payable ? Instant printout of weight, fat % and amount payable ? Fast, accurate & economical PC application for various other works at society TECHNICAL SPECIFICATIONS: MEASURING RANGE – Weight Measurement: 0 – 100 Kg. – Fat Measurement: 0 – 13% MEASURING CAPACITY: 120 – 150 OPERATION / HOUR POWER SUPPLY: AC: 220-240 V, 50 Hz [pic] SPV MODULES [pic] [pic][pic] FEATURES: High efficiency monocrystalline Silicon Solar Cells connected in series. ? Lamination using TEDLAR, Crane glass and EVA provides environmental protection. ? Solar cells laminated between UV resistant polymer (EVA) and high transmittivity toughened glass surface. ? Rugged weatherproof nylon terminal box for output connections. ? Anodized aluminum frame provides structural support for mounting and shock resistance. Manufactured to stringent quality standards and tested to withstand adverse environmental conditions. ? REIL Photovoltaic modules are approved by SEC, DoT and RDSO. APPLICATIONS: ? Domestic lighting systems ? Street lighting ? Water pumping ? Battery charging ? Community TV system ? Microwave repeater station ? Railway signalling and lighting systems ? Rural radio phones and exchanges Offshore platforms: ? Desalination plants ? Cathode protection systems ? Portable lantern ? Power pack for village electrification ? Crop sprayer ? Sign boards & Glow-signs TYPES OF MODULES [pic] [pic] Electrical specifications mentioned above are at standard test conditions of 100 mw / sq. cm. , AM 1. and at 25 degrees Centigrade cell temperature and are within normal production tolerance of +/- 10%. Due to continuous process innovations, the modules supplied may differ from those specified above. SPV STREET LIGHTING SYSTEM: This system provides un-interrupted light and is Completely noiseless, smoke-free and free from Fire hazards. The independent lighting system consisting of one PL-11 fixture, a storage battery charged by the SPV Modules and provides lighting during night hours. It automatically turns on in night and shuts off during the day. DEPLOYMENT [pic] REIL has supplied and installed over 9400 SPV Street Lighting Systems in various parts of the country.

These systems are working satisfactorily even under adverse climatic conditions of very high temperature, dust-storms, etc. APPLICATIONS: Street lights for areas away from grid supply ? As stand alone light at Farm Houses ? As warning signals at Railway crossings ? Out-of-the-way holiday locations ? Holiday cottages & caravans ? Campus Lighting SPECIFICATIONS Each SPV Street Lighting System comprises of following: Qty. 1. SPV Module 35 Wp – 2 2. 12 volts 80 AH Tubular Battery – 1 3. PL-11 Fixture, Dusk to Dawn operation – 1 with U. V. and O. C. protection 4. M. S. Structure for two modules (Set) – 1 5. Battery Box – 1 6. Interconnect wire-set – 1 7. M. S.

Pole – 1 8. Bend, pipe and hardware for frame (Set) – 1 SOLAR LIGHTING SYSTEM: [pic] The world cannot continue to rely for long on fossil fuels for its energy requirements. Fossil fuel reserves are limited. In addition, when burnt, these add to global warming, air pollution and acid rain. So solar photovoltaic systems are ideal for providing independent electrical power and lighting in isolated rural areas that are far away from the power grid. These systems are nonpolluting, don’t deplete the natural resources and are cheap in the long run. The aim of this circuit is to demonstrate how we can utilise solar light to electrify the remote areas, i. e. how we can store the solar energy and then use it for small-scale lighting applications. Solar cells generate direct current, so make sure that DPDT switch S1 is towards the solar panel side. The DC voltage from the solar panel is used to charge the battery and control the relay. Capacitor C1 connected in parallel with a 12V relay coil remains charged in daytime until the relay is activated. Capacitor C1 is used to increase the response time of the relay, so switching occurs moments after the voltage across it falls below 12V. Capacitor C1 also filters the rectified output if the battery is charged through AC power. The higher the value of the capacitor, the more the delay in switching.

The switching time is to be properly adjusted because the charging would practically stop in the early evening while we want the light to be ‘on’ during late evening. During daytime, relay RL1 energises, provided DPDT switch S1 is towards the solar panel side. Due to energisation of relay RL1, the positive terminal of the battery is connected to the output of regulator IC 7808 (a 3- terminal, 1A, 8V regulator) via diode D1 and normally-open (N/O) contacts of relay RL1. Here we have used a 6V, 4. 5Ah maintenance-free, lead-acid rechargeable battery. It requires a constant voltage of approx. 7. 3 volts for its proper charging. Even though the output of the solar panel keeps varying with the light intensity, IC 7808 (IC1) is used to give a constant output of 8V. Diode D1 causes a drop of 0. V, so we get approx. 7. 3V to charge the battery. LED1 indicates that the circuit is working and the battery is in the charging mode. At night, there will be no generation of electricity. The relay will not energise and charging will not take place. The solar energy stored in the battery can then be used to light up the lamp. A 3W lamp glows continuously for around 6 hours if the battery is fully charged. Instead of a 3W lamp, you can also use a parallel array of serially connected white LEDs and limiting resistors to provide sufficient light for even longer duration. In case the battery is connected in reverse polarity while charging, IC 7808 will get damaged.

The circuit indicates this damage by lighting up LED2, which is connected in reverse with resistor R2. However, the circuit provides only the indication of reverse polarity and no measure to protect the IC. A diode can be connected in reverse to the common terminal of the IC but this would reduce the voltage available to the battery for charging by another 0. 7 volt. There is also a provision for estimating the approximate voltage in the battery. This has been done by connecting ten 1N4007 diodes (D2 through D11) in forward bias with the battery. The output is taken by LED3 across diodes D2, D3, D4 and D5, which is equal to 2. 8V when the battery is fully charged. LED3 lights up at 2. 5 volts or above.

Here it glows with the voltage drop across the four diodes, which indicates that the battery is charged. If the battery voltage falls due to prolonged operation, LED3 no longer glows as the drop across D2, D3, D4 and D5 is not enough to light it up. This indicates that the battery has gone weak. Microswitch S1 has been provided to do this test whenever you want. If the weather is cloudy for some consecutive days, the battery will not charge. So a transformer and full-wave rectifier have been added to charge the battery by using DPDT switch S1. This is particularly helpful in those areas where power supply is irregular; the battery can be charged whenever mains power is available.