The Advent Of Energy Efficient Led Traffic Lights Engineering Essay

The coming of energy efficient LED traffic visible radiations has produced an unanticipated job in parts that experience stop deading temperatures and snowfall during the winter months. LED traffic visible radiations do non give off plenty heat to battle snow accretion and stop deading like older ( and more inefficient ) incandescent bulbs. Traffic light faculties that use candent visible radiation bulbs generate plenty heat to warm the lens and melt the snow. LED modules emit less frontward heat therefore leting snow to roll up over the light lens. These obscured signals present risky intersections which have led to accidents and loss of life.

In an attempt to extinguish this job, we will develop an automated warming system, LED Traffic Lights 4000, to de-ice LED traffic visible radiations in an energy efficient and cost effectual mode. To implement said efficiency, we will integrate detectors and command logic to find when each of the visible radiations needs de-icing. In add-on to the aforementioned control logic, we will utilize solar panels to supply the power needed for the constituents of our system in order to keep the energy nest eggs of LED traffic faculties.

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Some of the benefits and characteristics of our system are listed below.


Eliminate accidents attributed to traffic light privacy

Allow for the continued incorporation of LED traffic faculties

Maintain energy efficient unity of LED traffic faculties

Reduce costs of LED traffic faculty care






In order for our undertaking to go a feasible solution for the job in manus, there are some demands that must be met. To minimise costs, our solution must be guaranteed to run as expected for the life-time of the LED traffic visible radiation it is attached to. Grid power should be kept to an absolute lower limit which means that the power facet of the undertaking must be feasible during drawn-out periods of small to no sunshine. It besides has to run right 100 % of the clip, uncluttering ice/snow and observing jobs during both twenty-four hours and dark. A elaborate block diagram for our system is included in the appendix.

Figure 1

Heating Component:

We will utilize a subdivision of Nichrome wire as our warming component. Nichrome has a really high opposition per pes and is besides corrosion resistant. Since we plan to run our system at 12V, attention had to be taken to guarantee the proper gage wire was chosen so as to minimise the current through the wire, while still obtaining a temperature warm plenty to run the accumulating snow. Excessively much current through the wire could potentially do the lens of the LED visible radiation to partly run and deform, which would non be acceptable. The Nichrome wire we have chosen to use as our heating component will bring forth adequate heat to run snow with about 1 As of current. The 20 gage Nichrome wire has a opposition of about 0.6 ohms per pes. Ideally, we would wish to restrict the deicer power ingestion to no more than 12 Wattss. If we are using 12V to the wire, we would necessitate to utilize about:

of wire per visible radiation to keep a sensible current draw of 1 A. If we raise the gage of the wire to 28, we will be working with about 4 ohms per pes of wire. We would so necessitate merely 3 pess of wire per visible radiation to restrict our current to 1 A. If we chose to raise the wire gage to 31, we would acquire about 8 ohms per pes and merely necessitate 1.5 pess to accomplish a draw of 1 As. We will be carry oning field trials to find the optimum length of wire to utilize on a individual LED signal.

Figure 2

Power Storage:

A Battery will be used to hive away energy collected by the solar cells, so that the warming elements can run throughout the dark as needed. The storage system will be required to keep adequate charge to maintain the system working without external power for at least 12 hours, with 16+ hours desired. Without extended information from a paradigm of the proposed design, we can merely presume worst instance scenario computations for power storage. We assumed a typical operating temperature of no colder than because partly melted snowfall appears to be the sort that causes the most jobs. This makes intuitive sense since the snow would adhere to the lens more easy if it were wet. At these comparatively higher temperatures, stop deading rain can besides happen which would add to the job. Hence, we assume that the chance of the job happening additions with temperatures closer to stop deading. If we assume snow accumulates on the traffic visible radiation at a rate of one inch per hr, the longest the deicer would run is 30 proceedingss in a 90 infinitesimal clip period. The signal will stay clear for 60 proceedingss after each defrosting. If the deicers consume 12W/h, the PIC consumes 1W/h, and the remainder of the circuitry dissipates 1W/h, we get:

Based on the above W hr demands, we can state our battery will necessitate to be rated at:

Due to the nature of the lead acid battery, we can non allow the battery discharge wholly or else it could stop dead. We will size the battery so that it should n’t dispatch past 90 % which is near the threshold at. Besides, the cold temperatures we operate at farther cut down the capacity of the battery to 80 % of its rated capacity. With these considerations, our needed battery amp-hour evaluation becomes:


Power Proctor:

The power proctor will command the charging of the batteries, utilizing the available power from the solar panels. It will besides provide power from either the solar panels or batteries to the remainder of our system. Furthermore, if the batteries have been depleted and no solar energy is available, this unit must be able to exchange to grid power to keep all faculties operational. This unit will be purchased or sourced from the lab harmonizing to our demands, in order to ease concentration on more advanced parts of the undertaking.

Figure 3

Solar Collection:

Solar cells will be installed to minimise the cost of operation of the system, avoiding the usage of grid power whenever possible. This will enable the system to hold minimum impact on the energy nest eggs that LEDs provide over incandescent bulbs. The solar panels will necessitate to be able to bear down the power storage system to a sensible degree during the class of an mean Illinois winter twenty-four hours. Solar sunstroke informations suggests we can anticipate about 5 hours of direct sunlight per twenty-four hours in the winter. To bear down our batteries, we would so necessitate a solar panel that can bring forth:

If we assume the overall efficiency of our power system is approximately 60 % , we will necessitate a panel that can bring forth at least:

We have acquired an 80W panel that was used in old semesters, which will accommodate our demands adequately.

LED Signals:

LED traffic signals are installed in many locations throughout the state, several of which experience risky winter conditions. Our de-icing system will non necessitate particular traffic faculties ; it will be able to be attached to bing installings with minimum alterations. The lone alterations needed to put in our system are the fond regard of the warming component to the visible radiations and the photodiode used for sensing to the goons.


Photodiodes will be employed to supply the control unit with the information needed to make up one’s mind whether or non to trip the de-icers. The photodiodes must be capable of observing partial obstructors to the traffic visible radiations during twenty-four hours and dark. These photodiodes will be placed on the bottom of the goons, presently installed to cut down solar blaze. Puting the photodiodes in this place will minimise sunlight intervention and give them the best position of the traffic visible radiation as practically possible. The photodiodes invariably end product a electromotive force when the visible radiation is on and unobstructed. If snow accumulates in forepart of the traffic visible radiation, the electromotive force on the photodiode drops. Our circuit will utilize a comparator to signal the PIC when this alteration in electromotive force happens. Once the value drops below a threshold, the microcontroller will direct a indicant to the corresponding warmer to get down operating.

Control Logic:

The control unit will implement logic to accept input from the photodiodes and make up one’s mind if informations reported by them warrants de-icer activation or non. Accuracy is of import because the de-icer has to trip merely when needed and stay off all other times in order to salvage power. The control unit will take as an input a multiplexed signal from the traffic control faculty located near the intersection. The traffic control unit sends digital signals to the light faculties to turn them on or off. We plan to stop this control in order to merely look into our photodiodes merely in the event that the visible radiation to which it is attached to is on. A basic flow diagram for the control unit ‘s operation is shown in figure 4.

Figure 4

Figure 5

Performance Requirement

Our design undertaking must be able to execute its desired map while keeping the cost nest eggs associated with LED traffic visible radiations. It should besides be able to unclutter snow obstruction from traffic visible radiations before they become obstructed. This means observing early plenty, frequently plenty, and uncluttering the snow rapidly plenty to travel on to the following visible radiation if more than one is obstructed. The cost of the undertaking is besides of import because harmonizing to a 2003 study by the Consortium for Energy Efficiency, a ruddy LED traffic visible radiation costs about $ 300 dollars less over the expected seven twelvemonth life-time of the LED visible radiation. This sum does non include care. If we can maintain our solution cost below one hundred dollars per visible radiation, we believe the solution would be economically feasible.


The testing of our system will be done harmonizing to the undermentioned program for each faculty.


We will verify that the deicer works by imitating a covered traffic visible radiation and triping the deicer. We will mensurate the current and clip it takes to unclutter the snow from the lens of the traffic visible radiation to verify that both are below or at the specified thresholds. Snow rates have been known to make or transcend one inch per hr during snowstorms, so we will establish our worst instance scenario on that snowfall rate. Assuming the LED traffic visible radiation is coated with an inch of snow, we will prove how long it would take for the Nichrome wire to run approximately one inch of snow, utilizing different current values and/or different diameters of Nichrome. We will presume that the lowest temperature where the system needs to be operational is, and do certain the system can take snow at any temperature above that.

Power Storage

The power storage will be tested as lineation in the tolerance subdivision. We will imitate operating conditions, chiefly current draw at dark, and verify that it will work through a 14 hr dark.

Solar Panel

The solar panels will be given 5 hours to bear down our batteries in full sunshine, and the degree the batteries have been charged to must be at least 70 % ( maximal speedy charge degree ) .


Day/night sensing will be tested by imitating the operating conditions and detecting the behaviour of the system. The sensing circuit must be able to observe between A? and 2/3 obstructor and trip the defroster decently and quickly. This will be tested by imitating different degrees of light obstructor and doing certain the de-icers activate right.

Power Monitoring

To verify that backup exchanging plants, we will execute the trials described in the tolerance analysis. If batteries are depleted, the system draws power from the grid for every bit long as needed. This will be tested by unpluging the battery and detecting whether the system switches to grid power ( simulated in the power lab ) . This trial will look into the shift mechanism, which includes the comparator and relay.

Charge accountant

We will buy a commercial charge accountant to command the charging of the batteries. This portion of the system ensures that the batteries are being charged whenever needed if power from the solar panels is available. It besides avoids soaking the battery, which could do overheating and harm to the storage system. This part of the circuit will be tested by dispatching the battery with the charge accountant connected and so verifying that the charge accountant right disconnects the burden and charges the batteries via the solar panel.

Control Logic

We will verify that the control unit works decently and under assorted. We will prove it by imitating the inputs expected from the traffic visible radiation and detect the behaviour of the plan and circuit.

Tolerance Analysis

There are three parts to our tolerance analysis. First, we must vouch that the shift mechanism is performed such that the PIC public presentation is non affected. We are utilizing one of two comparators that are on the PIC. The end product of the comparator is used to trip the transistor which in bend allows plenty current to flux to the relay weaving to exchange to grid power. If the switch happens excessively easy, the PIC may lose power and the system would be away until the battery recharges. To prove the public presentation of the shift mechanism, we will imitate the battery being disconnected and observe the power inputs to the PIC. This will verify that the capacitance is of the proper size to keep a electromotive force above 4.5V for long plenty to let the shift to take topographic point. Another critical facet of our undertaking is doing certain we have adequate battery capacity to minimise grid use during expected operating environments. If the battery capacity is excessively little to back up expected conditions throughout the dark, the cost nest eggs associated with LED traffic visible radiations could be significantly reduced. We plan on verifying that our system battery capacity is satisfactory by imitating operation with the charge accountant disconnected, and greater than expected use. In this mode, we can verify that they battery can back up the burden throughout the dark. Finally, operational temperature extremes will run from -10 to +3 grades Celsius. The system constituents must be able to prolong temperature extremes from -40 to +50 grades Celsius without prolonging lasting harm. Manufacturers provide informations sheets for purchased parts stipulating operating tolerances for temperature and electromotive force degrees. Operation of the completed circuit will be analyzed in temperatures every bit utmost as can be practicably simulated.

Cost and Agenda:

A simplified cost analysis for our undertaking was done to gauge the cost of parts and labour for the completion of this system. It is shown below.

Assuming a wage of $ 50 per hr, per applied scientist, and 150 hours to finish the undertaking, the labour cost is estimated to be:


Part Number



Solar Panel



$ 329.99




$ 42.30

PIC Microcontroller



$ 4.75

Heating Component


9 foot

$ 0.20 / foot




$ 1.73




$ 0.10




$ 1.01




$ 10.49

Capacitor 2200MFD



$ 1.15




$ 1.13

Voltage Regulator



$ 1.25




$ 0.46

5 Ohm Resistor



$ 1.07

20 Ohm Resistor



$ 0.98

Charge Controller

Steca Solsum 8.0f


$ 20.95

The proposed agenda for the completion of this undertaking is detailed below. We estimate to hold the undertaking completed about 2 hebdomads before the official deadline.




1 ( 02/08 )



2 ( 02/15 )

Parts/Components needed


Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

3 ( 02/22 )

Purchase of parts needed, Design Review

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

4 ( 03/01 )

Constructing / Coding

Order PCB ( s )

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

5 ( 03/08 )

Constructing / Coding

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

6 ( 03/15 )

Testing / Debugging, Individual Reports

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

7 ( 03/22 )

Testing / Debuging

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

8 ( 03/29 )

Integration of faculties, Mock-Up Demos

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

9 ( 04/05 )

Integration of faculties, Mock-Up Presentation

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

10 ( 04/12 )

Finish Debugging and Project polish

Adan – Power Storage, Power Sources

Antonio – Detection, Power proctor

Chris – Snow Removal, Logic

11 ( 04/19 )

Individual Reports


12 ( 04/26 )



13 ( 05/03 )




Masters, Gilbert M. Renewable and Efficient Electric Power Systems. New Jersey: John Wiley & A ; Sons, Inc. , 2004.



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