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Density Sensed Street Light Intensity Controller – An Energy Saving ApproachDENSITY SENSED STREET LIGHT INTENSITY CONTROLLER – ANENERGY SAVING APPROACHSMRUTI RANJAN JAGADEB 1 , NALINI PRASAD MOHANTY 2 & RANJIT JENA 31,2&3 M. Tech. Scholar, Dept. of Electrical Engineering, National Institute of Technology, Silchar, Assam, INDIA.Abstract—High-intensity Discharge (HID) Lamps presently used for urban street light are based on principle of gasdischarge, thus the intensity is not controllable by any voltage reduction method as the discharge path is broken. White LightEmitting Diode (LED) based lamps are soon replacing the HID lamps in street light. Thus intensity control is now possibleby pulse width modulation based on sensing the movement and density of vehicles. The pulse width becomes very narrow onsensing no movement of vehicles. As the vehicle moves, the intensity goes on increasing for few lights ahead and as it passesaway, the intensity goes on reducing. Here, an attempt is taken to control the intensity of street light dynamically to saveenergy. A programmable microcontroller is engaged to provide different intensities at different density conditions.Keywords-LED; Microcontroller; Sensor; Voltage Regulator.I. INTRODUCTIONPhoto diodes (PD) are used at one side of the road.One switching transistor (ST) is meant for each PD.Each reversed biased PD is connected to the base ofthe ST. One infra-red (IR) diode faces each PD on theother side of the road. When no vehicle obstruction isthere, the IR ray falls on the PD forcing it to go intoconduction. So it biases the ST that conducts fromcollector to emitter like a switch. One variable resistoris used to control adequate base current of ST, asparameters of each conducting PD may be differentfrom each other, while IR rays fall upon. Theconducting ST develops a logic zero state at itscollector that feeds one of the Microcontroller (MC)pins that acts as an input. Eight such inputs are madeby above arrangement.II. DESCRIPTION OF COMPONENTSA. TransformerTransformers convert AC from one voltage toanother with little loss of power. Step-up transformersincrease voltage, step-down transformers reducevoltage. Most of the power supplies use a step-downtransformer to reduce the dangerously high mainsvoltage to a safer low voltage. The input coil is calledprimary coil and the output coil is called secondarycoil. The primary and secondary coils are linked byan alternating magnetic field created in the soft-ironcore of the transformer. Transformers waste verylittle power, so the power output is almost equal tothe power input.A step-down transformer has a large number ofturns on its primary (input) coil which is connected tothe high voltage main supply and a small number ofturns on its secondary (output) coil to give a lowoutput voltage.B. Voltage Regulator 7805The KA78XX/KA78XXA series of three-terminalpositive regulators are available in the TO-220/D-PAK package and with several fixed output voltages,making them useful in a wide range of applications.Each type employs internal current limiting, thermalshut down and safe operating area protection, makingit essentially indestructible. If adequate heat sinking isprovided, they can deliver over 1 amp output current,although designed primarily as fixed voltageregulators. These devices can be used with externalcomponents to obtain adjustable voltages and currents.The specifications of TO-220 are tabulated in Table I.TABLE I. ABSOLUTE MAXIMUM RATINGS OF TO-220ParameterSymbol Value UnitInput Voltage: (for V= 5 V to 18V)(for V = 24 V)Thermal Resistance Junction-Cases (TO-220)Thermal Resistance Junction-Air(TO-220)Operating Temperature Range(KA78XX/A/R)Storage Temperature RangeVIVI3540VVR JC 5 °C/WR JA 65 °C/WT OPRT STG0 ~+125-65 ~150LM7805 voltage regulator is a linear regulatorwhich comes in several types of packages. For outputcurrent up to 1A there may be two types of packages:TO-220 (vertical) and D-PAK (horizontal).With proper heat sink these LM78xx types canhandle even more than 1 A current. They also havethermal overload protection and short circuitprotection. In case, the design does not exceed 0.1amp current, then regulator LM7805 may be chosenwith smaller packages and lower maximum current upto 0.1 A. They come in three main types of packagesSO-8, SOT-89 and TO-92. LM7805 has an inputrange of 7-25 V and output of 5 V. Decoupling°C°CInternational Conference on Advanced Research in Mechanical, Electrical and Computer Engineering, 24- 26 th March 2013, Bangkok13

Density Sensed Street Light Intensity Controller – An Energy Saving ApproachTABLE II.Port PinFUNCTIONS OF PORT 3 OF THE AT89C51Alternative FunctionsP3.0 RXD (serial input port)P3.1 TXD (serial output port)P3.2 INT0 (external interrupt 0)P3.3 INT1 (external interrupt 1)P3.4 T0 (timer 0 external input)P3.5 T1(timer 1 external input)P3.6 WR (external data memory write strobe)P3.7 RD (external data memory read strobe)RST: It is an active high input pin. The high pulsemust be high at least 2 machine cycles.ALE/PROG: ‘’Address Latch Enable’’ output pulsefor latching the low byte of the address duringaccesses to external memory. This pin is also theprogram pulse input (PROG) during Flashprogramming. In normal operation, ALE is emitted ata constant rate of 1/6 th of the oscillator frequency andmay be used for external timing or clocking purposes.ALE is active only during a MOVX or MOVCinstruction; otherwise the pin is weakly pulled high.If the microcontroller is in external execution mode,ALE-disable bit has no effect.PSEN: Program Store Enable is the read strobe tothe external program memory. When the AT89C51 isexecuting code from external program memory,PSEN is activated twice in each machine cycle,except that two PSEN activations are skipped duringeach access to external data memory.EA/VPP: External Access Enable (EA) must bestrapped to GND in order to enable the device tofetch the code from external program memorylocations starting at 0000H up to FFFFH. EA shouldbe strapped to VCC for internal program executions.This pin also receives the 12-volt programmingenable voltage (VPP) during Flash programming, forthe parts that require 12-volt VPP.CRYSTAL1: Input to the inverting oscillatoramplifier and input to the internal clock operatingcircuit.CRYSTAL2: Output from the inverting oscillatoramplifier.D. LEDsLEDs are semiconductor devices like transistorsand other diodes. LEDs are made out of silicon. Thesmall amounts of chemical impurities that are added tothe silicon such as gallium, arsenide, indium, andnitride makes an LED lightened. When current passesthrough the LED, it emits photons as a by-product.LEDs produce photons directly; not via heat. An LEDis usually a small area (less than 1 mm 2 ) light source.The color of the emitted light depends on thecomposition and condition of the semiconductingmaterials.LEDs have a dynamic resistance that depending onhow much current passes through them. Amongthe specifications for LEDs, a "maximum forwardcurrent" rating is usually given. LEDs consume acertain voltage, known as the "forward voltage drop".A voltage source and a resistor are connected in seriesto drive an LED.E. Light SensorsLight sensors often use an infrared LED as a lightsource. Infrared LEDs have a greater intensity thanLEDs that emit visible light. When infraredphotodiodes are used in the sensors, they becomerelatively insensitive to ambient light. Photoelectriclight sources are often modulated at a givenfrequency to prevent interference from ambient light,but flashes or reflections can still full light-activatedsensors. This problem is solved by using a modulatedreceiver. Here the detector is synchronized to thelight source frequency. Photoelectric sensors are thedevelopment of modular devices. Sensor heads can becombined with a separate base and power supply andwith various logic options. Also the logic options canbe changed in the field without disturbing wiring orbeam alignment. This minimizes downtime andallows unskilled personnel to repair equipment.Fiber-optic cables are small, some are only about1/16 inch diameter and the fiber-optic head is usuallyjust a little larger. As a result, it can fit into tightspaces. Fiber optics can also be used in explosiveenvironments because all electrical signals areremote. Reflective light sensors (RLSs) are frequentlyemployed to sense an object's presence because theyare easy to use. An RLS differs from other lightsensors in that the target does not simply break a lightbeam but reflects light to a detector. RLSs are lesssensitive to ambient light and can detect minute ortransparent objects. Some devices can even determinethe distance between sensor and object, therebyoffering an alternative to ultrasonic systems. While ingeneral, RLSs are becoming smaller, two divergenttrends are emerging as well. One group of sensors isbecoming simpler, basically containing only a lightsource and detector. Sensor output is a simple on/offsignal, and users provide the power supply and signalprocessing circuitry. The other group is becoming fullfeatured. These devices contain a power supply andlogic. Users programmed the devices by settingswitches or with a PC. Sensor manufacturers areintegrating advanced devices like solid-state lasers.Usually the power supply for the laser and anamplifier for the signal output are contained in aseparate unit. An advantage of placing systemfunctions in different packages is that the sensor iskept small.F. IR transmitterIR Transmitter carriers at around 40 kHz carrierfrequencies are widely used in TV remote controlling.The circuit can be controlled using any TTL or RS-232C level control signal which makes the interfacingvery simple.International Conference on Advanced Research in Mechanical, Electrical and Computer Engineering, 24- 26 th March 2013, Bangkok15

Density Sensed Street Light Intensity Controller – An Energy Saving ApproachFigure 3. (a) Circuit Diagram of IR Transmitter (b) IRTransmitterThe circuit can be used for computer to generate IRremote control signals or experimental IR datatransmission. The circuit diagram and figure of IRtransmitter are shown in Fig.3. The componentswhich are used for IR transmitters are listed below:C1 1 nFC2 10 nFC3 220 nFD1 D2 1N4148D3 TIL31B (or other suitable IR LED)R1 1 kΩR2 22 kΩ trimmerR3 120 ΩU1 NE555, LM555 or similarIII.CONSTRUCTION AND WORKINGFourteen Bright White LEDs (WL) representing asstreet light are fed from the MC output pins thatnormally provides 10% duty cycle pulses (while no IRray is blocked, simulating a no vehicle movement)that glows dim. As the vehicle reaches the first IR, itblocks the ray falling on the PD that deprives the STbias to result in off condition at its pulled-up collectorthat sends a logic high to the corresponding MC input.The program then takes effect inside MC in making itsoutput of few WLs ahead to get 99% duty cycle pulsesto glow brighter. As the vehicle advances to block thenext IR ray, so advances the WLs and so on it followsahead while the trailing IR one is unblocked to resumeto 10% duty cycle to glow dim.Figure 4. Block DiagramWhenever vehicles enters into the road, the photosensors which are placed on either sides of the roadwill detect and the 7 LEDs from the sensing point outof 14 LEDs which acts as street light will go high toglow in one mode and will change from dimmed tofull glow in another mode according to program. Theblock Diagram of the total arrangement is shown inFig. 4. First, 230 volt AC main is converted to 12 voltAC through a step-down transformer. The 12 volt ACis then fetched to the rectifier, which convert the ACvoltage to DC voltage. This 12 volt DC voltage isunregulated, so called as pulsating DC. For obtaining5 volt fixed DC, a voltage regulator (LM7805), whichconvert the pulsating DC to fixed DC is used. The 5volt DC (fixed) is given to the microcontroller. Anappropriate program is written in C or Assemblylanguage, which is converted into machine language.The same is loaded to the microcontroller in HEXformat with the help of a programmer. There are suchnumber of IR receivers and IR transmitters, which areplaced on both sides of the road. There are someLED’s, which are run by the program that is loaded inthe microcontroller. The LED’s are treated as thestreet light. The street light is based on whatever theposition of the vehicle. When the road is obstructed bythe vehicle, LEDs from 1 to 7 start glowing as per theprogram. When the vehicle crosses the first streetlight, then the next seven LEDs i.e. from 2 to 8 startglowing and the first LED glows dim because of noobstruction. The process continues to run in the samemanner.IV. WORKINGEach line of an assembly program can containonly one control, directive or instruction statement.Statements must be contained in exactly one line.Multi– line statements are not allowed. Statements inx51 assembly programs are not column sensitive.Controls, directives and instructions may start in anycolumn. Indentation used in the programs in this workis done for program clarity and is neither required norexpected by the assembler. The only exception is thatarguments and instruction operands must be separatedfrom controls, directives and instructions by at leastone space.V. CONCLUSIONIt is apparent from the current set up that tworobust approaches can lead to save energy as far as thearrangement of street lights in the highways areconcerned. Firstly, the replacement of currentfluorescent lamps by LEDs are cost effective and lesspower consuming with equivalent intensity and lessvoltage requirement. Secondly, the arrangement canbe achieved by low investment and in turn saves moreenergy by automatically dimming of LEDs in notraffic situation. Depending upon the easy visibility ofInternational Conference on Advanced Research in Mechanical, Electrical and Computer Engineering, 24- 26 th March 2013, Bangkok16

Density Sensed Street Light Intensity Controller – An Energy Saving Approachthe driver and average positioning of the lamps in thehighways, the present arrangement considers that outof 14 LEDs, 7 LEDs are simultaneously glow to avoidaccident. However, due to flexibility of the circuit, themicrocontroller can be reprogrammed to control anynumber of lamps at a time.REFERENCES[1] Chun-ling Fan and Yuan Guo “The Application of a ZigBeeBased Wireless Sensor Network in the LED Street LampControl System”, International Conference on imageAnalysis and Signal Processing (IASP), 2011, pp. 501 – 504.[2] C. M. De Dominicis; A. Flammini; E. Sisinni; L. Fasanotti;F. Floreani; “On the development of a wireless self localizingstreetlight monitoring system “, Sensors ApplicationsSymposium IEEE, pp. 233 - 238 ,2011.[3] E. Tetri, L. Halonen, Future trends of energy efficientlighting, Proceedings, 26th Session ofthe CIE, Beijing, China,4-11 July 2007, pp. 45-48[4] F. Argatu, C. Cepisca, Modeling dynamic high intensitydischarge lamp characteristics, U.P.B. Sci.Bull., Series C,Vol.72, Iss.3, 2009[5] Gustavo W. Denardin, Carlos H. Barriquello, AlexandreCampos, Rafael A. Pinto, “Control Network for ModernStreet Lighting Systems”, IEEE symposium on IndustrialElectronics (ISIE), (2011), pp. 1282 – 1289.[6] J. L. Huang, Z. F. Wang, L. G. Li, and L. H. Wang ” Basedon Zig Bee smart wireless lighting wall controller design“Chinese Journal of Scientific Instrument, vol. 30, no. 6, June2009.[7] John M. Anderson “First Electric Street Lamps” IEEE PowerEngineering Review, pp.39-40, Mar. 2000.[8] L. Guo, M. Eloholma, L. Halonen, Luminance monitoringand optimization of luminance metering in intelligent roadlighting control systems, Lighting Engineering, Vol. 9,2007,pp. 2440.[9] M. A. D. Costa, G. H. Costa, A. S. dos Santos, L. Schuch andJ. R. Pinheiro (2009), “A high efficiency autonomous streetlighting system based on solar energy and LEDs”, BrazilianPower Electronics Conference (COBEP 2009), Bonito, 27September-1 October, pp. 265-73.[10] R. Caponetto, G. Dongola, L. Fortuna, N. Riscica and D.Zufacchi (2008) “Power consumption reduction in a remotecontrolled street lighting system”, International Symposiumon Power Electronics, Electrical Drives, Automation andMotion (SPEEDAM 2008), Ischia,une, pp. 428-33.[11] Wu Yue; Shi Changhong; Zhang Xianghong; Yang Wei;“Design of new intelligent street light control system “,, 8thIEEE international Conferences on Control and Automation(ICCA), ( 2010) , Page(s): 1423 – 1427..International Conference on Advanced Research in Mechanical, Electrical and Computer Engineering, 24- 26 th March 2013, Bangkok17