EEE4036C - Group Assignment (Beta Version)

8/4/2019 EEE4036C - Group Assignment (Beta Version)

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Faculty of Engineering and the Built Environment

Department of Electrical Engineering

EEE4036C Electrical Engineering Design

Group Assignment

Prepared By:

Michael Rainey (RNYMIC001)

Jesse Dicks (DCKJES003)

Shana Peters (PTRSHA019)

1 September 2011


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Table of ContentsDesign Specifications .................................................................................................................................... 5

Functional Characteristics ......................................................................................................................... 5

Safety Characteristics ................................................................................................................................ 5

Quality Assurance ..................................................................................................................................... 5

Timescale .................................................................................................................................................. 5

Economic Factors ...................................................................................................................................... 5

Ecological Factors ...................................................................................................................................... 5

Aesthetic Factors....................................................................................................................................... 5

Life-Cycle ................................................................................................................................................... 6

Design Context .............................................................................................................................................. 6

Macroeconomic Factors ........................................................................................................................... 6

Social ..................................................................................................................................................... 6

Technical ............................................................................................................................................... 6

Environmental ....................................................................................................................................... 6

Economic ............................................................................................................................................... 7

Political .................................................................................................................................................. 7

Microeconomic Factors ............................................................................................................................ 7

The Market ............................................................................................................................................ 7

Resources .............................................................................................................................................. 7

The Customer ........................................................................................................................................ 8

Corporate Factors ..................................................................................................................................... 8

Corporate Enviroment .......................................................................................................................... 8

Corporate Structure .............................................................................................................................. 8

Corporate Systems ................................................................................................................................ 8

Corporate Strategy ................................................................................................................................ 8

Shared Values ........................................................................................................................................ 8

Managment Style .................................................................................................................................. 8

Management skill .................................................................................................................................. 8

Management skill .................................................................................................................................. 8

Project proposal and task clarification ......................................................................................................... 9


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Interested parties ...................................................................................................................................... 9

Client ..................................................................................................................................................... 9

User ....................................................................................................................................................... 9

Eskom .................................................................................................................................................... 9

Conflict Resolution .................................................................................................................................. 10

Competitors ............................................................................................................................................ 10

Design Task ............................................................................................................................................. 10

In the following section, we discuss all the aspects of our design in relation to this project. ............... 10

Magnitude ........................................................................................................................................... 10

Complexity .......................................................................................................................................... 10

Novelty ................................................................................................................................................ 10

Production Quantity and Quality ........................................................................................................ 10

Technical Risk ...................................................................................................................................... 10

Delivery Time Constraints ................................................................................................................... 10

Requirements of Stakeholders ................................................................................................................ 11

Client ................................................................................................................................................... 11

User ..................................................................................................................................................... 11

Project Proposal (Scope of Work) ........................................................................................................... 12

Phases and Tasks: ................................................................................................................................ 12

Timeline ............................................................................................................................................... 14

Design review meetings ...................................................................................................................... 15

Decision points .................................................................................................................................... 16

Acceptance Test ...................................................................................................................................... 16

Systems Diagram of Design Tasks ........................................................................................................... 19

Design Concept ........................................................................................................................................... 20

Concept Idea 1 ........................................................................................................................................ 20

Concept Idea 2(Sci-Fi) ............................................................................................................................. 21

Concept Idea 3 ........................................................................................................................................ 22

Cost Estimate .......................................................................................................................................... 23

Embodiment design .................................................................................................................................... 24

Description of Solar hot water Systems .................................................................................................. 24

Description of the electrical back up system .......................................................................................... 24


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Heating Element & Thermostat .......................................................................................................... 25

Temperature Sensors .......................................................................................................................... 25

Digital Controller ................................................................................................................................. 26

Micro controlled Relay circuit ............................................................................................................. 28

Power Supply ...................................................................................................................................... 28

Failure Modes ......................................................................................................................................... 29

Design and Safe life time estimates ........................................................................................................ 29

Worst Case Design .................................................................................................................................. 30

Standards and Codes .............................................................................................................................. 31

Detailed Design - Digital Controller Subsection .......................................................................................... 33

Schematic Circuit Diagram ...................................................................................................................... 33

Description of the equipment and principals involved ....................................................................... 33

The implementation............................................................................................................................ 33

PCB board layout..................................................................................................................................... 37

Description of the equipment and principals involved ....................................................................... 37

The implementation............................................................................................................................ 37

Pseudo code ............................................................................................................................................ 38

Program flow chart ................................................................................................................................. 38

Detail Design worksheet Digital controller .......................................................................................... 39

Design quality assessment worksheet .................................................................................................... 40

Manufacturing of Digital controllers ....................................................................................................... 41

Testing procedure for digital Controllers ................................................................................................ 41

User manual ............................................................................................................................................ 42

Detailed Cost Estimate ............................................................................................................................ 42

Appendix A .................................................................................................................................................. 44

References .................................................................................................................................................. 45


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Design Specifications

The Department of Electrical Engineering requires the design of an electrically powered backup for a solar water

heater, which will be installed into an existing 200 litre capacity solar water heater system. The electrically

powered backup system may be incorporated in the main storage cylinder or it may be provided in one or moreseparate components between the solar water heater and the points of use of hot water. The completed product

needs to adhere to the following design specifications.

Functional Characteristics

Small in size No moving parts Heating element to integrate directly into solar water heating tank Temperature and pressure sensor Controller is multi-functional with temperature and pressure inputs Controller can be set for fixed water temperature output Auto-circulate, freeze protection and clock function

Safety Characteristics

Proper electrical insulation Auto-leak detection and over-heat detection with corresponding shut-off function No environmental hazards or safety concerns

Quality Assurance

Must conform to SABS, ISO and IEC standards Must undergo and pass an extensive testing period Must perform reliably

Timescale

Design period 1 month Development period 6 months Production period 6 months Delivery period 1 month

Economic Factors

Market analysis potential to save huge amount of money by user on electrical bills Design cost R10000 Development, manufacturing, distribution cost per unit R2000

Ecological Factors

No ecologically hazardous or damaging materials or liquids to be usedAesthetic Factors

Low profile unobtrusive in appearance


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Life-Cycle

Have an approximate life time of 20 years Requires minimum maintenance when used within normal operating parameters Can be disposed of as normal electronic waste

Design Context

Macroeconomic Factors

Social

Effect on the community in which the product will be:Designed;Manufactured;Recycled

Job creationThe design will be simple enough to install so that it creates jobs for skilled and unskilled workers. It shall

ensure work for at least 1 electrician, 1 plumber and 1 unskilled aid per installation

Occupational safetyThe insulation and earthing will be according to industry standards to ensure maximum safety against

electrocution. The design shall come equip with visual aid warning such as: danger of electrocution;

correct use of personal protection equipment when installing, warning against storage of flammable

material near the vicinity of the system. The design will be encased in such a way as to prevent injury to

people (especially children) and vandalism.

Community attitudes to the projectThe community will have a positive attitude towards the project as it will save them money. It will also

revive a much needed culture of electricity saving that has been deteriorating since load shedding ceased.

Technical

Life cycle of technologyThe research and development stage should be kept as short as possible in order to see returns on the

clients investment as well as other interested parties.

Whole life-of-project technology issuesThe product can be deemed useless if newer technologies arrive. The design should thus be flexible

enough to incorporate newer technologies.

Appropriateness to other steep factors..

Environmental

Resource usage and manufacturing cost to environmentThe design should ensure minimal to no water wastage by using sealing. During the manufacturing phase

care should be taken to ensure environmentally safe resources are used to minimise the cost to the

environment.

End of project life issuesThe design should, as far as reasonably practicable, use recyclable material. Disposal information should

be given to the customer indicating the safest method of disposal of non-recyclable materials.


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Economic

Financial backgroundThe design should not use unnecessarily expensive technologies and materials. This will ensure our final

product is cost effective and financially viable.

Sensitivity analysis,Tax/legislation......

Globalization issuesThe design should use, as far as reasonable practicable, South African products in order to stimulate

economic growth in our country. Capacity building

Community issuesThe cost of the product should be reasonable enough so that is pays itself back in at least one year

Political

InterestConsidering the recent electricity crisis in South Africa, citizens would respond positively to a government

that supports projects aimed at improving electricity utilization. The government would thus have a

vested interest in this project as it would stimulate more efficient use of electricity.

Impending political change

Microeconomic Factors

The Market

Demand for productSolar water heaters are in high demand for financial reasons as electricity tariffs are becoming

increasingly expensive. Solar water heaters are also becoming more popular as the green approach is

being adopted both locally as well as globally. In South Africa, especially Cape Town, weather varies

rapidly and one cannot rely on the sun alone for water heating. This makes the demand for a back up

systems for our heaters very high. Competitors

Our competitors are existing manufacturers of backup systems as well as other designers who look to

improve on existing designs. It can be assumed that the competition is high. Some competitors include

amongst others: Haining Fadi Solar Energy Co; Foshan Shunde Jnod Electrical Appliance Co; Jiangsu

Audary New Energy Co etc.

Financial Risk and market stageThere is a certain level of concern with the financial return on the product as not many people have yet

embraced the idea of greener products or more effective electricity usage. The market is however in its

early adopters stage and growing bigger as the country is constantly encouraging energy saving.

Resources

Human ResourcesThe designers are 3 electrical engineering graduates qualified to produce the most optimum design. If the

tender is awarded technical staff will be employed to manufacture and distribute the design. We will also

ensure that an employee is constantly liaising with the cl ient to ensure no miscommunication.

Documentation

Financial ResourcesThe University of Cape Town will finance the project if the tender is awarded. No finances are necessary

during the design phase.


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Design information, technology and materials availabilityInformation regarding components and existing designs is readily available on the internet. Appropriate

technology and materials exist for an optimum design

Energy RequirementThe energy requirement for the design is reasonable as it would use mains electricity to operate

The Customer

The Department of Electrical Engineering at UCT are the primary customers. Based on the request forproposal it is evident that the customer does understand the need for this product. The customer expects

a full design proposal by the 1st

of September. It is vital that this due date be met so that manufacturing

can commence if approved.

Corporate Factors

Corporate Enviroment

Corporate Structure

Corporate Systems

Corporate Strategy

Shared Values

Managment Style

Management skill

Management skill


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Project proposal and task clarification

Interested parties

Client

The Electrical engineering department at the University of Cape Town is the client.Requirements

The client has put in a request for proposal for a design of an electrical back up for a solar water heater with the

following specifications:

o Functionality: It must work in such a way as to conserve as much electricity as possible while still beingfunctional. It must be able to heat a tank of size no less than 200 litres. It must be easy to use by the

householder

o Safety: It must be safe to use for both the installer as well as the usero Quality: It must be in accordance with all the appropriate standardso Manufacturing:o Timing: It must be complete by the 1st of September 20o Economic: It must be cost effectiveo

Ergonomic:o Ecological: It must be environmentally friendlyo Aesthetic:o Life-cycle:o Other:

User

The users of our product will be homeowners that wish to have hot water.

Requirements

We have assumed requirements that the user might have for the product:

o Functionality: It must be easy to useo Safety: It must be safeo Quality:o Manufacturing:o Timing:o Economic: It must save the user a considerable amount of money on electricityo Ergonomic:o Ecological: It must be environmentally friendlyo Aesthetic: If it is not hidden (in the roof, basement etc.) it must be aesthetically pleasingo Life-cycle:o Other:

Eskom

Eskom will also be a stakeholder in this project as it is an electrical appliance that aims at to saving electricity.

Requirements

o Functionality: It must work in such a way as to conserve as much electricity as possible. It must run at thestandard 60 Hz frequency. It must not dissipate too much power (maximum..)o Safety: It must be safe to use for both the installer as well as the usero Quality: It must be in accordance with all the appropriate standardso Manufacturing:o Timing:o Economic:o Ergonomic:o Ecological: It must be environmentally safe


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o Aesthetic:o Life-cycle:o Other:

Conflict Resolution

Conflicting needs will be resolved by assuring open communication between us and the stakeholders. Weekly

meetings will be held with the clients to ensure no issues are left unresolved. Users will be able to contact us via

internet, email, or telephonically to discuss any discrepancies that they might have with the product. Eskom...

Competitors

Our competitors might put forward a better proposal if there design concept is more original than ours or

designed with a better price. .....

Design Task

In the following section, we discuss all the aspects of our design in relation to this project.

Magnitude

Our project can be classified as medium, in terms of size and scope, for our three person team of engineers. We

should be able to handle all areas involved with the design with little to no difficulty.

Complexity

As our team consists of three f inal year electrical engineering students, we are more than able to understand all

aspects involved with this project, and hence to create the required proposal and final design.

Novelty

The general technology involved with electrically powered backup is not new or novel. However, we will be

examining different possible design concepts and finally recommend one of these as the optimal choice. Some of

these designs may incorporate some novel ideas which could add time and complexity to the design, if it turns out

to be the concept of choice.

Production Quantity and Quality

As we are a small team, we will start our venture on a small scale. Once our design is completed, we plan to build

only a few systems of high quality, and then to gradually increase our production rate as the venture expands.

Technical Risk

As already mentioned, we are experts in regards to electrical systems, and the general technology is well

understood and developed. We will also be choosing our recommended design based on using the best, safest andmost reliable technology. Hence, we foresee no serious technical risks.

Delivery Time Constraints

As we are consistently working on our design, we are assured it will be completed in time. Once production starts,

as only a few systems will be built initially, we believe we will be able to conform to all the necessary time

constraints.


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Project Proposal (Scope of Work)

In this design project the specific requirements are to prepare a design report of an electrically powered backup

for a solar water heater. The backup heating and controller design is only required for the scope of the design

project.

The scope of work required is only design report, and not testing, manufacturing and production of the detailed

design. The design report includes the project identification, the design context, the project proposal and task

clarification, design concepts, embodiment design, and finally the detailed design.

The specific detailed scope of work carried out by our design team will be described in detail below, including the

phases and tasks, timescales, design review meetings, and the decision points discussed throughout the project.

The scope of work will only entail everything required to produce the design report and nothing more.

Phases and Tasks:

All the tasks below were compiled in this report

Phases: Tasks:

Project identification and the design context Determining the client and the key performancedetails of the product/system.

Prepare a specification list (client requirement) forthe design task for this new product/system.

Determine the macroeconomic, microeconomic,corporate factors/issues that might be considered

in choosing the best solution. Show how these

factors/issues are relevant and important to your

design.

Project proposal and task clarification

Identify the interested parties and theirrequirements for the project. (Client, users, and

other stakeholders)

Determine how the conflicting needs of theinterested parties can be resolved.

Determine how competitors can produce a betterproposal.

Assess the design specification based on theinterested parties needs, and how well it defines

the design task needed.

Produce a statement of the scope of work.Including the phases and tasks, timescale, design

review meetings, and decision points.

Prepare an acceptance test for the design stage. Produce a systems diagram of the main

components of the design task and its context.

Design concepts Develop four concept designs for the project.Including all the main components of the system

and diagrams. Discuss the benefits of each concept

design.

A complete evaluation of the concepts, including


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the weak points.

Selection of the concept recommended for thedesign with reasons.

A cost estimation of the selected concept.Embodiment design Description of selected concept design (including

diagrams, circuits, etc.)

List of the possible failure modes, withprobabilities, consequences and the required

actions to alleviate the problem.

Description of the design life limit with the safe lifelimit, and what factors will limit it.

A detailed worst-case calculation on one or morecomponents or sub-systems of the design.

A description of at least one standard or code thatapplies to our design.

Detailed design Preparation of the detailed design for one sub-system, including the following:

A description with details of the design (diagrams,drawings, circuit diagrams, calculations, etc.)

Produce a detailed design checklist Complete the design quality assessment

worksheet.

Description of the manufacture process to be takenfor the product or sub-system.

Description of the testing process to be taken forthe product or sub-system, during or after the

manufacture/installation.

Create a table of contents for the user/installationmanual or help files.

Create a detailed cost estimate for the supply ofthe product/system, including all costs. (Design,manufacture, delivery, salaries, etc.)

Design review: Compare the design with therequirements of the initial design specification.

Produce the acceptance test for the design activity.


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Timeline

StartMon 8/1/11

FinishThu 9/1/11

Mon Aug 1Thu Aug 4Sun Aug 7Wed Aug 10Sat Aug 13

Fri Aug 19Mon Aug 22Thu Aug 25Sun Aug 28Wed Aug 31

Design Group FormationMon 8/1/11 - Sun 8/7/11

Project identification and the design

contextMon 8/8/11 - Fri 8/12/11

Project proposal and task clarificationSat 8/13/11 - Mon 8/15/11

Design conceptsTue 8/16/11 - Thu 8/18/11Embodiment design

Fri 8/19/11 - Mon 8/22/11

Detailed designTue 8/23/11 - Mon 8/29/11

Design review and hand inTue 8/30/11 - Thu 9/1/11


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Design review meetings

At end of every project phase we met for a design phase review meeting. During which we discussed the tasks and

the problems encountered by each project member. Further we discussed the next step to take, the decisions and

choices we had to make, and allocated the work evenly and accordingly to match the strengths of each member.

The table below shows the meetings scheduled.

Meetings: Date & Time: Purpose:

Group formation 8/1/2011

13h00

To form a dynamic project team, and to assess our

strengths and weaknesses.

Phase 1 8/8/2011

13h00

To discuss the design task presented to us (i.e. the scope of

work, structure, initial tasks for phase 1 and allocation of

work).

Phase 1 review 8/12/2011

13h00

Review of phase 1 by assessing the issues that came to

light, and compiling phase 1 in the report document.

Further to discuss the tasks for phase 2, along with

allocating the work.


13h00

Review of phase 2 by assessing the tasks and making

decisions on rectifying the problems encountered, and

compiling phase 2 in the report document. Further to

discuss the next phase tasks, and allocating the work.


13h00

Review of phase 3 by assessing the problems that arose

and rectifying them, and compiling phase 3 in the report

document. Decisions were made on proposed concept for

phase 4. Further to discuss the next phase tasks, and

allocating the work.


13h00


decisions on rectifying the problems encountered, and

compiling phase 4 in the report document. Further to



13h00


decisions on rectifying the problems encountered, andcompiling phase 5 in the report document. Further to


Complete Design review and hand in 8/31/2011

13h00

Review of the design project as a whole, assessing how

well it fits the initial design specification. Proof reading the

final draft document and submission.


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Decision points

The decision points discussed were the concept design to be chosen, the functionally of the detailed design, how

well the detailed design meets the clients specifications, how well the design meets the design context, design life

time and the safe life time of the system to be chosen, whether found codes or standards is applicable to our

design, and finally the software coding to be implemented.

Decision No. Description of the decision to be made: Chosen decision:

Decision 1: Design concept to be chosen. Design concept 4, as it is the most likely concept to

work and is most cost and power efficient design.

Decision 2: Functionally of the detailed design. The functionally meets the specifications

requirements and also allows for future

development of the product.

Decision 3: How well does the detailed design meet

the clients specifications?

Very well, it fits the specification almost perfectly.

Decision 4: How well the design meets the design

context.

Very well, it fits the design context in all

microeconomic, macroeconomic and corporate

factors.

Decision 5: Design life time and the safe life time of the

system to be chosen.

It was chosen accordingly; refer to the relevant

section in the embodiment design.

Decision 6: Whether found codes or standards are

applicable to our design.

They are very applicable; refer to the relevant

section in the embodiment design.

Decision 7: The software coding to be implemented. This was chosen based on the three principle

modes of operation, deluxe, energy efficient, anduser defined mode. Refer to embodiment design

on specific details of these modes.

Acceptance Test

Once the design is complete the client will overlook the following check list to assure that the design has met the

specifications. If a specification is not met the design will be revisited until it satisfies all conditions. An example of

what to do when a specification is unmet is marked in red.


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Specification Complete

(Y/N)

If No, Give details and specify

remedial action to be taken

Re-evaluation

Date:

Functional:General

Is the size 20x400?

N The design is 30x40. Re-design

to meet specification

03-09-2011

Are there any moving parts?

Is the heating element integrated inside the

water tank?

Sensors

Are the temperature sensors situated on the

appropriate places

Are the pressure sensors situated on the

appropriate places?

Controller

Is the controller is multi-functional withtemperature and pressure inputs?

Can the controller be set for fixed

temperature outputs?

Does the controller have Auto-circulate,

freeze protection and clock function?

Safety

Special features

Does the design include auto-leak and over-

heat detection with corresponding shut-off

function?

Does a battery backup exist?

Standard complianceIs the electrical insulation according to

standard.....?

Is the electrical supply according to

standard.....?

Is the battery back up according to

standard....?

Environmental Safety

Are there no environmental concerns?

Quality Assurance

Is the design in accordance with SABS

standard.....?

Is the design in accordance with ISOstandard....?

Is the design accordance with IEC standard...?

Time

Was the design submitted by the 01-09-

2011?

Economic

Is the design cost less than/ equal to R10000

Is the unit price estimate less than/equal to

R2000?

Ecological

Are there no ecologically

hazardous/damaging materials /liquids used?


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Aesthetic

Is the design unobtrusive in appearance?

Life-Cycle

Is it designed to have an approximate life

time of 20 years?

Does it require minimum maintenance when

used within normal operating parameters?Can it be disposed of as normal electronic

waste?


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Systems Diagram of Design Tasks

y y y y

y

n nn

n

Initial Client Request

Design Specification

Desi n 1 Desi n 2 Desi n 3 Desi n 4

Best

Best

Best

Best

Final Design Concept

Test and Refine Final Design

Procure, Assemble, Prepare

Assemble, Manufacture, Prototype

Satisfactory?

Test Prototype

Deliver Product

Working Product

Assemble, Manufacture, Product


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Design Concept

The following section contains four developed ideas as possible design concepts of the electrically powered backup

system for a solar water heater, to be installed into an existing 200 litre capacity solar water heater system.

Concept Idea 1

This concept of the electrically powered backup system consists of an electronic controller incorporated into the

main storage cylinder of an existing solar water heater. The controller turns on an electric heating element, if the

water temperature in the main cylinder drops below the desired level. The controller will be multi-functional

consisting of an input pad with which one can set the threshold temperature, a timer, etc. It will contain

temperature and pressure sensors to monitor the state of the water at all times, as well as an alarm and auto shut

off.

Components:

230 V AC Supply Cables Electric heating element Sensors Electronic controller

o Multi-functional programmable coreo Digital displayo Keypado RS232 port for installing upgrades

Advantageous:

Meets all requirements, plus extra features Non-intrusive installation Ease of use Most efficient use of energy Most efficient in terms of monetary savings Onboard safety systems such as auto shut off

Disadvantageous:

More complex circuitry More expensive components More programming


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Concept Idea 2(Sci-Fi)

This concept of the electrically powered backup system, consists of a highly advanced electronic controller,

incorporated into the main storage cylinder of an existing solar water heater (same general setup as for Idea 1),

with a sensitive EM-field generator and sensor. The solar system has a confined water flow system that heats upthe useable water of the main storage cylinder. The confined water of the solar heating system contains 0.5%

specially constructed nanites, and 25% of a specially designed Carbon-Argon-Indium compound, by mass. These

nanites have been created using the biological microorganismEscherichia coli. If the water temperature in the

main cylinder drops below the desired level, the nanites can be controlled with a special EM-field, to cause the

slow gradual breakdown of the compound, which releases enormous amounts of heat in the water, as well as safe

and inert molecular by-products. Thus by varying the EM-field, the rate of molecular breakdown can be controlled,

and hence the change in temperature of the water.

Components:

230 V AC Supply Cables EM-field generator EM-field sensor 1kg of JX027-ECOLI Nanites 40L of (Cx-Ary-Inz) liquid compound Controller Battery Backup Electronic controller

o Multi-functional programmable Quad-Core processoro Digital displayo Keypado USB3 port for installing upgrades

Advantageous:

Meets all requirements Least-intrusive installation Most savings on electricity (only used to

control nanites)

Can heat water even when there is a power outage (battery controls EM-field)Disadvantageous:

New technology that hasnt been tested extensively Most complex circuitry Most expensive components Most complex programming required Nanites needs to be replaced every 5 years (Cx-Ary-Inz) liquid compound needs to be replaced every year
http://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_coli


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Concept Idea 3

The electrical back up system for a solar water heater designed here consists of two heating element units, two

temperature sensors, a digital controller key pad, and the wiring to these components.

The heating element unit is tubular steel unit with built in heating and sensing components. The unit screws

directly into the copper piping, allowing water to flow through it while getting heated. These units are located on

both sides of the storage tank, as illustrated in the diagram below. The heating element components consists of

two built in temperature sensors located on the ends of the unit, one flow rate meter, one a heating element coil

located within the centre of the tube covering a large surface area of the waters flow path, and finally a thermostat

for control of the heating element.

The temperature sensors are also located on the solar collectors input and output pipes. The sensors units consist

of small housings that are bolted around the copper piping and the temperature sensor embedded within the

housing.

The final component is the digital controller. This consists of 8 ADC inputs, 3 DAC outputs, 16 button keypad, LCD

display, Pic32 and Pic18 microcontrollers, USB connectors, wireless communication sender/receiver, and an

internet/telephone jack.

The benefits of this system are that the installation of the system fairly easy, any qualified plumber can do the job.

It requires minimal alterations to the existing solar water heating system, and has no interference with the storage

tank at all. It can have additional digital control algorithms programmed into the system; it can be updated,

monitored and controlled by remote access from the utility company. The down side to this system is that it

required two heating elements and relays, a more complicated microcontroller with more sensing equipment

required, thus twice the power and cost requirements.


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Cost Estimate

Category Main

Components

Sub - Components Component Cost No. of

Components

Total Cost

ProductComponent

Cost

Hot watercylinder

components

Heating element(3KW) R218 - 59 1 R218 - 59

Element gasket R8 - 95 1 R8 - 95

Thermostat with

fuse

R165 - 00 1 R165 - 00

Thermo sensor -

screw in (for hot

water cylinder)

R60 - 00 1 R60 - 00

Digital Controller

+ sensing +

wiring

components

Variable fit pipe

mounted temp

sensor

R60 - 00 2 R120 - 00

Digital Controller

Unit

R300 - 00 1 R500 - 00

Wiring for temp

sensors (10m) 2

core

R4 00/m 3 R120 - 00

Wiring for pump

motor (10m) 3

core

R6 00/m 1 R60 - 00

Wiring for heating

element (10m) 3

core

R8 00/m 1 R80 - 00

Relay for heating

element control

R65 - 00 1 R65 - 00

Wiring for digital

controller powersupply (5m) + plug

R6 00/m + R5

(for plug)

1 R35 - 00

Wiring for heating

element (5m) 3

core

R8 00/m 1 R40 00

Manufacturing and packaging costs Manufacturing of

digital controller

R200 - 00 1 R200 - 00

Acquiring all other

components

R30 - 00 1 R30 - 00

Packaging of final

product

R50 - 00 1 R50 - 00

Design and administration costs R247 - 46 1 R247 - 46

Total Product Cost R2000 - 00


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Embodiment design

Description of Solar hot water Systems

The electrical backup system for the solar water heater is designed to operate on the two most common solar

water heating systems available. These systems will be described below so that sufficient knowledge is understood

in order to design the electrical back up system for these topologies.

The first system is the passive open loop system. This system is commonly called the thermo siphon. It operates by

solar collectors being either placed on the roof or on the ground where sufficient sunlight can be absorbed. The

storage tank is placed directly above the solar collector this so that the hot water produced from solar will rise

directly into the storage tank, while pushing the cold water at the bottom of the tank through the bottom of the

solar collectors. [1]

The second system is the active solar water system. This system has two variations, the first is the active open loop

system, and second is the active closed loop system. The active open loop system consists of the solar collectors

been placed on the roof of a house while the storage tank placed inside the house. The cold water at the bottom of

the storage tank is pumped up into the bottom of the solar collectors, and the hot water leaving the top of thecollectors is circulated back into the top of the storage tank. [2]

The active closed loop system works similarly to the open loop. The major different is that the fluid circulating

through the solar collectors run through a different system compared to before when the water in the storage

tank circulated through the solar collectors. This hot fluid from the top of the solar collector passes through a heat

exchanger inside the storage tank, and is then circulated back into the bottom of the solar collector via an electric

pump. This is to prevent freezing/boiling of water in the solar collectors during extreme conditions. Thus in the

isolated system, antifreeze mixture can be added to the fluid preventing it from freezing/boiling. This prevents

damage to the solar collectors. [2]

Description of the electrical back up systemThe electrical back up system that has been chosen consists of the following components: A heating element &

thermostat, three temperature sensors, digital controller, power supply, a micro controlled relay, and various

wiring connecting the heating element, pump, and temperature sensors to the digital controller.


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Heating Element & Thermostat

The heating element is mounted horizontally into storage tank. The dimensions of the element are 56mm by

127mm deep, where 56mm is the screw in thread size. A pre allocated location for a heating element half way up

on the wall of the storage tank is designed into all of the common solar water heating systems. This was designed

for the option to install a heating element for back up. The elements were not pre-installed as it would increase

the overall cost of their product. However the option for additional installation is simple. The heating element

screws into the location with gasket that will be provided. A typical thermostat used in all geysers will be provided

as a secondary fail-safe backup to prevent overheating of the tank. The primary fail-safe backup for overheating

will be the control of the relay using the digital controller. The heating element is connected to a relay controlled

by the digital controller. It is further connected via DAC outputs on the controller. This controller controls when the

heating element will switch on and off depending to the conditions of the system to maintain an efficient use of

electrical energy.

Temperature Sensors

An immersion temperature sensor is installed into the side of

the storage tank via one of the heating element ports. (See

appendix A for details on the storage tank [3]). The heating

element port is a 56mm female thread, so for the

temperature sensor to be installed a bushing is needed to

reduce the size from 56mm to 27mm (refer to figure 4). Once

the thread is reduced to 27mm the pocket housing can be

screwed in (see figure 3), and followed by the immersion

sensor (see figure 2). The temperature is measured accurately

and its value is read to the digital controller via the ADC inputs.

Two further temperature sensors are installed on to the inlet and outlet

of the solar collectors and are linked to the digital controller via the ADC

inputs. The sensors are exterior pipe mounted temperature sensors

obtained from certain suppliers. These sensors are able to accurately

measure the temperature of the fluid flowing inside the pipe. These

sensors provide valuable information of the current state of the system

to the controller. The use of the information these sensors provide will


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be discussed in the detail functionally of the digital controller, as it directly relates to the efficient use of the

heating element and pump.

Digital Controller

The digital controller is designed to control the heating element and the variable speed drive pump efficiently to

maximize the output of hot water from the solar water system. The controller consists of two microcontrollers, an

LCD display, a 16 button keypad, three ADC inputs, two DAC outputs, a wired communication RJ-45 jack, and a USB

port.

The microcontrollers that are going to be used are the PIC32MX360F512L and PIC18F4550QFN. The reason for two

microcontrollers being used is that the Pic32 chip (that has superior processing power, memory and functionality)

does not have a USB interface for programming. The Pic18 chip has this functionally so these two chips are linked

together via the JTAG ports, so the Pic32 chip can be programmed through the USB interface on the Pic18 chip.

The ADC inputs are set up with adjustable gains so the voltage can be adjusted between (3V 18V) on the input of

the ADC. This allows for compatibility with the temperature sensors that will be connected to the ADC inputs. The

DAC outputs have the exact same setup, as 12V is required for the micro controlled relay for the heating elementand even less (between 3V 12V) for the chopper circuit on the variable speed drive DC pump.

The variable speed drive DC motor commonly used in solar water heaters is controlled by the microcontroller by

connecting the PWM output to the gate of the IGBT in a DC chopper circuit. It will be a class A chopper only which

will only operate in one quadrant (forward motoring).

The wired communication interface is setup so that the software on the microcontrollers can be automatically

updated providing the latest and best control methods to obtain the most energy efficient system through the

internet site created for this purpose. Its also created for the possibility to be connected to the utility company

through the internet, so that the solar water systems can be controlled remotely. This is to provide even greater

savings to the users by using energy when the tariffs are low, and also to help reduce the peak load on the national

grid by using energy at alternative times of the day when the load is low.

There are two pre-defined modes programmed into the controller, and a manually setup control mode to meet the

users exacts needs from the solar water system. The Pre-defined modes are the deluxe mode and the energy

efficient mode.

For the control scenarios the following variables have been defined:

Temp1 Outlet solar collector temperature sensor Temp2 Inlet solar collector temperature sensor Temp3 Storage tank temperature sensor

Pump Variable speed drive DC motor Element heating element

The deluxe mode is for users who want hot water at any time of the day while still saving some money when the

solar collectors are transferring heat to the tank. The system is to maintain a temperature of 60 degrees in the

storage tank at all times. The control system will continuously be reading the three temperature sensors. The

following scenarios can occur and the control system must be programmed accordingly.


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Scenario 1: If temp3 < 60 and temp1 = temp2. Control systems response: pump off; element on till temp3 = 60.

Scenario 2: If temp3 < 60 and temp1 > temp2. Control systems response: pump on (flow rate will depend on the

difference between temp1&2, large difference in temp1&2 will have a larger pump flow rate);

element off.

Scenario 3: If temp3 < 60 and temp1 < temp2. Control systems response: pump off; element on till temp3 = 60.

Scenario 4: If temp3 > 60 and (temp1 < temp2, temp1 > temp2, temp1 = temp2). Control systems response:

pump off; element off.

Energy efficient mode is for users whose main interest is saving energy and money. This control mode will only

provide guaranteed hot water at 55 degrees during certain times of the day (5:30am 8:00am and 5:00pm

9:00pm). These times are based on times when most people are awake and at home, thus majority of the users

who only use hot water at these times will not notice any difference to their hot water supply. The following

scenarios can occur and the control system must be programmed accordingly.

Scenario 1: If temp3 < 55 and temp1 = temp2 and time within intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump off; element on till temp3 = 60.

Scenario 2: If temp3 < 55 and temp1 > temp2 and time within intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump on (flow rate will depend on the difference betweentemp1&2, large difference in temp1&2 will have a larger pump flow rate); element off.

Scenario 3: If temp3 < 55 and temp1 < temp2 and time within intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump off; element on till temp3 = 60.

Scenario 4: If temp3 > 55 and (temp1 < temp2, temp1 > temp2, temp1 = temp2) and time within intervals

(5:30am 8:00am and 5:00pm 9:00pm). Control systems response: pump off; element off.

Scenario 5: If temp3 < 55 and temp1 = temp2 and time not within intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump off; element off.

Scenario 6: If temp3 < 55 and temp1 > temp2 and time not within intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump on (flow rate will depend on the difference between

temp1&2, large difference in temp1&2 will have a larger pump flow rate); element off.

Scenario 7: If temp3 < 55 and temp1 < temp2 and time within not intervals (5:30am 8:00am and 5:00pm

9:00pm). Control systems response: pump off; element off.Scenario 8: If temp3 > 55 and (temp1 < temp2, temp1 > temp2, temp1 = temp2) and time not within intervals

(5:30am 8:00am and 5:00pm 9:00pm). Control systems response: pump off; element off.

Manual mode is for users who want hot water at certain times of the day, and at a certain temperature. The users

will push the button for manual mode, and will then be asked to enter the start time of interval (in 24h00 mode)

followed by the enter button. It will then ask user to enter the end time of interval followed by enter. It then asks

for the temperature of the hot water they would like. Then the controller will ask if the user would like to enter

other interval, and the user will be faced with an option (Yes press 1, No - press 2), and if no is pushed the setting

will be saved and implemented, otherwise it will begin to setup the next interval by asking the user to enter the

time of the next interval start, etc.

The display on the digital controller will display the time in the top right hand corner, the storage tanks

temperature in the top left, the mode that is running (deluxe, energy efficient, or user defined mode) in the top

middle. If the system detects a fault it will display the fault type in the center of the display, faults types will be

explained in user manual.


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Micro controlled Relay circuit

The heating element is controlled by the digital

controller and therefore to control it the system

will require a relay to open and close the heating

element circuit which is connected to the mains

(230VAC). The low voltage side of the relayoperates at 12V. This voltage is adjusted down to

3.3V by the variable gain op amp circuit connected

to the DAC pins. See figure 6 below for the relay

circuit.

Power Supply

The power required for the digital controller is 15V DC. This voltage will then get regulated to -15V, 5V and 3.3V on

the main circuit board. This is the entire power requirement for the digital controller. The 15V DC will be rectified

from the mains supply, using an instrument transformer with voltage ratio 230VAC: 16.4VAC and a full bridge

rectifier with a smoothing capacitor.

Figure 7: Power supply, taken from [7].


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Failure Modes

Failure Mode Probability Consequence

Sensors

Failure to detect/ give in correctreadings

medium The system would turn on/off incorrectly or not at all.Over heating

Power supply

Short circuiting medium Equipment could break. Possible electrocution if the user

is touching the power supply

Overload medium Equipment could break. Possible electrocution if the user


Controller

False outputs to the heating

element

low The system would turn on/off incorrectly or not at all.

Over heating

Display might indicate incorrect

measurements

low User might switch the device on/off unnecessarily

Keypad could fail to work low ....

Low power supply to the controller medium The controller will switch on thus the system will not

work

High power supply to the

controller

low The controller will over heat and break

Heating element

Corrosion of the heating element high Water contamination.

Battery

Short circuiting medium Equipment could break. Possible electrocution if the user


Battery acid leakage low Equipment can break.

Seals

Leakage through the seals high Loss of water and possible flooding of the surrounding

area.

I NEED TO SEE FULL DESIGN IN ORDER TO SEE WHAT OTHER COMPONENTS EXIST

Design and Safe life time estimates

The design life as well as Safe life of the system is estimated at 20 years. The safe life would decrease if any of the

above failure modes occur and is not attended to.


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Worst Case Design

Our electrically powered backup system requires electricity to work. This electricity will be supplied via 230 V AC.

The controller itself however requires an input of 15V DC. This input is then further voltage regulated to supply 5V

DC and 3V DC. An important component then to consider when doing worst case calculations is the subsystem thatchanges the AC voltage to the desired DC voltage.

To convert the AC voltage to DC voltage, you firstly need a transformer (to step down the 230V AC), then a full -

wave rectifier (consisting of 4 diodes for uncontrolled or 4 thyristors for controlled rectification), and finally a low

pass filter (consisting of a resistor and a capacitor).

Figure 1 Rectifier

One can now use the general rectifier equation to find the value of, which will be the midpoint voltage on thesecondary side of a single tap transformer, for , which is the desired output.

Thus,

So the primary side voltage is 230 V and the secondary side is approximately 16.6 V. The turns ratio of the

transformer is then,


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Now for a worst case calculation, suppose the AC voltage delivered is not exactly 230 V. Assume a maximum of 240

V and a minimum of 220 V. What will be the corresponding voltage delivered to the controller ()? The previouscalculations are now performed in reverse order and the results are summarized in the next table.

220 V 15.7 V 7.85 V 14.1 V

230 V 16.6 V 8.3 V 15 V

240 V 17.1 V 8.57 V 15.4 V

Hence, from this its clear that the incoming DC voltage which the controller receives may be as low as 14 V and as

high as 15.5 V. Our system therefore needs to be designed to handle these possible fluctuations. One approach is

through the careful selection of the capacitor for the low pass filter that is in parallel with the voltage source. If the

voltage source is higher than the capacitor voltage, the capacitor will pull the voltage down, and if it is lower, the

capacitor will pull the voltage up, essentially smoothing out the voltage to some average. There is also a resistor

between the voltage source and capacitor to prevent too much current from flowing into the capacitor.

Standards and Codes

Since we are designing an electrically powered backup for a solar water heater, which will be installed into an

existing 200 litre capacity solar water heater system of a household, the following seems to be the most relevant

standards: SANS 60730-2-8 and 60335-2-21

The following table are copied in its entirety (to give a detailed outlook of the standard) from the following

website:https://www.sabs.co.za/webstore/standards/product.php?id=14012228

SANS 60730-2-8

Title Automatic electrical controls for household and similar use Part 2-8:

Particular requirements for electrically operated water valves, including

mechanical requirements

Date Approved 10-10-2003

Edition 1.01

Amendments 1A: International:03/10/2003

Abstract Applies to electrically operated water valves for use in, on or in

association with equipment for household and similar use that may use

electricity, gas, oil, solid fuel, solar thermal energy, etc. or a combination

thereof, including heating, air-conditioning and similar applications.International Relatedness IEC 60730-2-8

Date Reaffirmed 12-12-2008

Issued By STANDARDS

Price (ZAR, excl. VAT) 194.00

Shipping Costs (Hardcopy) SeeTerms & Conditionsfor more details.

Stage Code 91.60: Standard Reaffirmed

Stage Date 2009-02-16
https://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/user/Webstore_Terms_and_Conditions.pdfhttps://www.sabs.co.za/webstore/user/Webstore_Terms_and_Conditions.pdfhttps://www.sabs.co.za/webstore/user/Webstore_Terms_and_Conditions.pdfhttps://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/standards/product.php?id=14012228https://www.sabs.co.za/webstore/user/Webstore_Terms_and_Conditions.pdfhttps://www.sabs.co.za/webstore/standards/product.php?id=14012228


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Committee 72

ICS Number 97.120

ISBN 0-626-14898-7

Collection This standard is not part of a collection

Cross-reference

Standards Alert Service Register now, to receive notifications about this standard.

The following table are copied in its entirety (to give a detailed outlook of the standard) from the following

website:https://www.sabs.co.za/webstore/standards/product.php?id=14009025

SANS 60335-2-21

Title Safety of household and similar electrical appliances Part 2-21: Particular

requirements for storage water heaters

Date Approved 08-08-2000

Edition 1.00

Abstract Deals with the safety of electric storage water heaters for household and

similar purposes and intended for heating water below boiling

temperature, their rated voltage being not more than 250 V for single-phase appliances and 480 V for other appliances. Covers appliances

intended to be used by laymen in shops, in light industry and on farms.

Deals with the common hazards presented by appliances which are

encountered by all persons in and around the home.

International Relatedness IEC 60335-2-21

Replaces SANS 60335-2-21( SABS IEC 60335-2-21 edition 1.000 of 1998)

Use In Conjunction With SABS IEC 60335-1

Issued By STANDARDS

Price (ZAR, excl. VAT) 159.00

Shipping Costs (Hardcopy) SeeTerms & Conditionsfor more details.

Stage Code 60.60: Standard Published, in use

Stage Date 2000-08-04

Committee 72

ICS Number 91.140.65

ISBN 0-626-12585-5

Collection This standard is not part of a collection

Cross-reference Shoppers buying this also bought:

SANS 151

SANS 1307SABS IEC 60335-1

Standards Alert Service Register now, to receive notifications about this standard.
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Detailed Design - Digital Controller Subsection

Schematic Circuit Diagram

Description of the equipment and principals involved

Eagle Cad v5.10 PIC32MX360F512L-80I/PT - Microchip PIC32 32bit microcontroller PIC18LF4550-I/ML - Microchip PIC18 USB microcontroller RJ45 Jack SN74HCT541 - Octal line driver 2* LM317 - 1.5A adjustable voltage regulator LCD - 16 character 2 line LCD PIC32MX3XX-4XX+Family+datasheet Various other datasheets for required components Various resistors, capacitors, leds, and crystals.

The implementation

It began by reviewing the datasheet for the pic32 microcontroller, and connecting up all the basic connection

requirements for the microchip on eagle cads schematic layout. This involved choosing/connecting the two

crystals (8 MHz and 32 KHz) for the pic32 microchip, setting up the decoupling capacitors, setting up the capacitor

on the internal voltage regulator, and setting up the master clear pin with a reset button. (See figure 10)

Connection for the pic18 and pic32 microchips were implemented next via the JTAG ports; this was to enable USB

communications to the pic32 chip which did not have the functionally. Next connecting up the LCD display was

done via the octal line driver chip to the pic32 microchip this also included a potentiometer for adjusting the

display brightness. Connection of the 16 button key pad which was connected directly to the ports on pic32 chipwas done next. (Refer to figure 8, 9 and 10 for implementation.)

Next setting up the ADCs and DACs was implemented, using two inverting opamps for each I/O so the voltage

gain could be varied between 3V - 18V. (One with unity gain and the other with variable gain using a

potentiometer). The push buttons were then connected next via the ports. The USB port was connected to the

pic18 microcontroller. (Refer to figure 8 and 9 for implementation.)

Finally the power supply for the microcontrollers, octal line driver is set up using the 15V rail rectified to a 5V rail

and further rectified to a 3.3V rail. I did this done by using an adjustable regulator. The various connections were

made for the components power needs (5V and 3.3V). (Refer to figure 8 to see how the power supply was set up.)


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PCB board layout

Description of the equipment and principals involved

Eagle cad v5.10

PIC32MX3XX-4XX+Family+datasheet PIC18F2455-2550-4455-4550+data+sheet

The implementation

Components were placed in various locations across the board in Eagle CAD, keeping in mind that the RJ- 45 and

USB connectors need to be at the edge of the board. The microcontrollers (pic18 and pic32) have restrictions on

how far the decoupling capacitors can be located from the chips, thus review of the datasheets was needed to find

out the maximum distance. Once the capacitors were placed within the maximum distance to the microchips, the

placement of the rest of the components was done using both sides of the board. The design settings were chosen

specifically to meet the requirements of the machine that cuts the tracks and drills the holes in the board in the

department. Drill sizes, minimum clearance between tracks and the track width, etc. was all chosen. (See f igure 11)

Figure 11: PCB layout of digital controller ready for printing.


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Pseudo code

1. Initialize all start conditions (variable name indicated in parenthesis)

Set heating element off ( Heat_el) Set the desired temperature to 60C (Set_temp) Set the delay to 5 seconds (delay)

Initialize a variable for the actual temperature, reading taken from the temperature sensor, andinitially set it to 60C (Act_temp)

2. Delay for 5 seconds before taking the first reading

3. Take the reading from the temperature sensor

4. Is the temperature sensor reading smaller than the set temperature?

5. Is the heating element off?

If 4 and 5 are both true switch on the heating element and repeat from step 2 If 4 and 5 are both false switch off the element and repeat from step 2 If 4 is true and 5 is false repeat from step 2 If 4 is false and 5 is true repeat from 2

Program flow chart

b) Detail design checklist

Act_Temp


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Detail Design worksheet Digital controller

Requirements Contributing factors Current

status

Required

action

Functional Geometery:

Is the circuit board 20x40mm?

Motion of parts:Are all the parts firmly connected to the circuit board?

Energy needed:

Is there a 3v supply/transformer

Materials:

Does the hardware include:

1. Apic32 chip2. USB system for communications to PC, including

programming

3. Keypad and/or pushbuttons4. Display (LCD that displays either text or bits)5. Analog inputs (12 bits with two or more channels)6.

Analog output (12 bits)Control system:

Is the controller reset compatible?

Informational flow:

Is the program logical?

Forces involved

Safety Operational:

Human:

Does the controller have overvoltage protection?

Environmental:

Are the materials used able to withstand harsh temperature

conditions?

Quality Quality assurance:

Quality control:

Reliability:

Manufacturing Production of components:

Are the components that are produced in working order?

Are the components that are produced according to standard?

Purchase of components:

Are the components that are purchased in working order?

Are the components that are purchased according to standard?

Assembly:

Is the assembly according to the design?

Timing Has the design been completed on time?

Economic Has the design been completed within budget?Ergonomic

Ecological Are there any materials used that are harmful to the environment?

Aesthetic Is the circuit board neat?

Is the casing compact and neat?

Life-cycle


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Design quality assessment worksheet

very clueless


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Manufacturing of Digital controllers

All electronic hardware will be ordered from local manufactures (e.g ). The choice of which manufacturer will

demand on price and quality of the components. We will then use EAGLECAD to construct our schematics of the

circuit board. We will use FR-4 laminate for our printable circuit board. The laminate is flame retardant and

constructed from glass fabric impregnated with epoxy resin and copper foil .We will use LPKF Protomat S42 system

to create our printable circuit board. This machine will etch our schematic onto the laminate creating a working

circuit board.

Figure:LPKF Protomat S42

The laminate will then be coated with a green solder mask. All the components (resistors, capacitors, IC mounts

etc.) will be soldered onto the circuit board. After testing a conformal coating will be added in order to protect

against environmental impact. The circuit board will then be fully enclosed in a Perspex housing.

Testing procedure for digital Controllers

The following testing procedure has been laid out for the digital controller. After manufacturing and assembly of

the digital controller the electrical circuit will be tested. This will be done in the following manner. The digital

controller will be powered up, and an oscilloscope will be used to test and measure the following below, these

results will be checked to see whether they lie within their spec value range:

The DC voltage on the power supply to see whether it is in the correct range (14.5 15.5 with the DCripple less than 1V.

The regulated voltages will be tested next, +/-15V, 5V, and 3.3V rails. Various power rail pins will then be tested on the microcontrollers and ICs across the board.

The digital controllers that pass the previous testing phase will then be factory programmed with the software

code required for operation. Finally these digital controllers will be connected to the testing rig. (the complete

system) They will then be check rigorously in the system for controller functionally, correct operation, and how the

controller handles its self during fault conditions. Once the digital controller passes all these tests it will be qualitycontrol accepted and then be ready for packaging.


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User manual

1. Introduction1.1. Operational procedure1.2. Initializing

2. Components2.1. Hardware

2.1.1.Push button operation2.1.2.Display2.1.3.Printed circuit board2.1.4.Casing

2.2. Software2.2.1.Operational flow2.2.2.Memory Map2.2.3.Default settings

2.3. Power Supply3. Installation

3.1. Mounting3.2. Wiring4. Safety4.1. Safety warnings4.2. Fault detection4.3. Troubleshooting

5. Regulatory Requirements5.1. Standard compliance

6. Contact Information7. GlossaryDetailed Cost Estimate

All of the materials were sourced for other companies, so delivery of the materials required is incorporated into

the cost. The only parts manufactured are the power supply, digital controller and the DC chopper drive. All onlyparts were sourced from various companies. The pricing for delivery of materials is done on a per unit basis, and

normally 200 500 units will be manufactured at a time.

Category Main

Components

Sub -

Components

Basic -

Components

Component

Cost

No. of

Components

Total Cost

Product

Component

Cost

Hot water

cylinder

components

Heating

element (3KW)

Heating element R217 - 59 1 R218 - 59

Supply delivery/

unit

R1 00 1

Element gasket Element gasket R8 00 1 R8 - 95

Supply delivery/

unit

R0 - 95 1

Thermostatwith fuse

Thermostat withfuse

R164 - 00 1 R165 - 00

Supply delivery/

unit

R1 00 1

Thermo sensor

-screw in (for

hot water

cylinder)

Thermo sensor R55 - 00 1 R60 - 00

Supply delivery/

unit

R5 1


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43 | P a g e

Wiring for temp

sensors (10m)

2 core

Wiring (10m) R40 00

(R4 00/m)

1 R41 00

Supply delivery/

unit

R1 - 00 1

Wiring for

heating

element (10m) 3 core

Wiring (10m) R7 90/m 1 R80 - 00

Supply delivery/unit

R1 - 00 1

Relay for

heating

element control

Material Costs R64 - 00 1 R65 - 00

Supply delivery/

unit

R1 - 00 1

Digital

Controller

Digital

Controller Unit

Material Costs R350 - 00 1 R437 - 00

Wiring for digital

controller power

supply (5m) +

plug

R6 00/m +

R5 (for

plug)

1

Supply delivery

for materials

R10 00 1

Power Supply

Unit (230VAC to

15VDC)

Material Costs R40 00 1

Supply delivery

for materials

R2 - 00 1

Solar Collector

temperature

Sensors

Wiring for temp

sensors (10m)

2 core

Wiring(10m) R40 00

(R4 00/m)

2 R82 - 00

Supply delivery/

unit

R1 - 00 2

Variable fit pipe

mounted temp

sensor

Temp sensor R58 - 00 2 R120 - 00

Supply delivery/

unit

R2 - 00 2

DC Motor(Pump) Drive

DC ChopperDrive

Material Costs R20 - 00 1 R22 - 00Supply delivery/

unit

R2 - 00 1

Wiring for

Pump (10m) 2

core

Wiring (10m) R6 00/m 1 R61 00

Supply delivery/

unit

R1 - 00 1

Product manufacturing and

packaging costs

Manufacturing

of digital

controller

- R100 - 00 1 R100 - 00

Manufacturing

of Power Supply

and DC

Chopper

- R30 - 00 1 R30 - 00

Packaging of

final product

- R20 - 00 1 R20 - 00

Design and administration costs - R388 - 46 1 R388 - 46

Delivery of product to client R100 +

(R1/product

delivered)

1 R101 - 00

Total Product Cost R2000 - 00


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45/45

References

[1]http://solarheatcool.sustainablesources.com/#PASSIVEDHW

[2]http://solarheatcool.sustainablesources.com/#ACTIVEDHW

[3]http://www.bradfordwhite.com/images/shared/pdfs/manuals/238-47073-00C.pdf

[4]http://www.omniinstruments.co.uk//images/downloads/2523.pdf

[5]http://www.samallen.com.au/sinks.pdf

[6]http://www.iq3.cn/trend/UploadFile/SENSORS/ds_tpi.pdf

[7]http://www.kpsec.freeuk.com/powersup.htm

[8]http://csalarmsystems.com/faq.html
http://solarheatcool.sustainablesources.com/#PASSIVEDHWhttp://solarheatcool.sustainablesources.com/#PASSIVEDHWhttp://solarheatcool.sustainablesources.com/#PASSIVEDHWhttp://solarheatcool.sustainablesources.com/#ACTIVEDHWhttp://solarheatcool.sustainablesources.com/#ACTIVEDHWhttp://solarheatcool.sustainablesources.com/#ACTIVEDHWhttp://www.bradfordwhite.com/images/shared/pdfs/manuals/238-47073-00C.pdfhttp://www.bradfordwhite.com/images/shared/pdfs/manuals/238-47073-00C.pdfhttp://www.bradfordwhite.com/images/shared/pdfs/manuals/238-47073-00C.pdfhttp://www.omniinstruments.co.uk/images/downloads/2523.pdfhttp://www.omniinstruments.co.uk/images/downloads/2523.pdfhttp://www.omniinstruments.co.uk/images/downloads/2523.pdfhttp://www.samallen.com.au/sinks.pdfhttp://www.samallen.com.au/sinks.pdfhttp://www.samallen.com.au/sinks.pdfhttp://www.iq3.cn/trend/UploadFile/SENSORS/ds_tpi.pdfhttp://www.iq3.cn/trend/UploadFile/SENSORS/ds_tpi.pdfhttp://www.kpsec.freeuk.com/powersup.htmhttp://www.kpsec.freeuk.com/powersup.htmhttp://www.kpsec.freeuk.com/powersup.htmhttp://csalarmsystems.com/faq.htmlhttp://csalarmsystems.com/faq.htmlhttp://csalarmsystems.com/faq.htmlhttp://csalarmsystems.com/faq.htmlhttp://www.kpsec.freeuk.com/powersup.htmhttp://www.iq3.cn/trend/UploadFile/SENSORS/ds_tpi.pdfhttp://www.samallen.com.au/sinks.pdfhttp://www.omniinstruments.co.uk/images/downloads/2523.pdfhttp://www.bradfordwhite.com/images/shared/pdfs/manuals/238-47073-00C.pdfhttp://solarheatcool.sustainablesources.com/#ACTIVEDHWhttp://solarheatcool.sustainablesources.com/#PASSIVEDHW

Documents

EEE4036C - Group Assignment (Beta Version)