SuPER PROJECT WIRING AND SYSTEM …jharris/research/...SuPER PROJECT WIRING AND SYSTEM PROTECTION by Jennifer Cao Senior Project ELECTRICAL ENGINEERING DEPARTMENT California Polytechnic

SuPER PROJECT WIRING AND SYSTEM PROTECTION

by

Jennifer Cao

Senior Project

ELECTRICAL ENGINEERING DEPARTMENT

California Polytechnic State University

San Luis Obispo

2006

ii

TABLE OF CONTENTS

Section Page

List of Figures and Tables…………………………………………………….iii

Acknowledgements…………………………………………………………….v

Abstract………………………………………………………………………..vi

I. Introduction……………………………………………………………………1

II. Background…………………………………………………………………....3

III. Requirements………………………………………………………………….7

IV. Design………………………………………………………………………..11

V. Testing………………………………………………………………………..19

VI. Conclusions and Recommendations…………………………………………30

VII. Bibliography…………………………………………………………………32

Appendices

A. Parts List and Cost……………………………………………………………….33

B. Time Schedule Allocation………………………………………………………..36

iii

LIST OF FIGURES AND TABLES

Figures Page

1. Simplified SuPER System Block Diagram…………………………………………5

2. SuPER System Wiring Diagram…………………………………………………..13

3. SuPER System Combiner Box and Load Outlets…………………………………16

4. SuPER System Switchboards Junction Box……………………………………....17

5. SuPER System Wiring, Rearview……..……………………………………….….18

6. Motor Current Draw vs. Torque…………………………………………………..21

7. Motor Power vs. Torque…………………………………………………………..22

8. Motor Speed vs. Torque…………………………………………………………...22

9. Motor Voltage vs. Torque…………………………………………………………23

10. Motor Efficiency vs. Torque……………………………………………………..23

11. Operational Motor Current Draw vs. Torque……………………………………25

12. Operational Motor Power vs. Torque……………………………………………26

13. Operational Motor Speed vs. Torque…………………………………………….26

14. Operational Motor Voltage vs. Torque…………………………………………..27

15. Operational Motor Efficiency vs. Torque………………………………………..27

16. Motor Speeds vs. Torque Comparison…………………………………………...28

Table Page

I. SuPER System Daily Use……….…………………………………………………..4

II. SuPER System Currents……………………………………………………………7

iv

III. SuPER System Load Currents…..………………………………………………...8

IV. DC Motor Characteristics………………………………………………………..21

V. Operational DC Motor Characteristics…………………………………………...24

VI. Price List and Cost……………………………………………………………….33

VII. Estimated Time Schedule……………………………………………………….36

VIII. Actual Time Used………………………………………………………...……37

v

ACKNOWLEDGEMENTS

I would like to dedicate my senior project to my parents and friends for all of

their support and encouragement. I would like to give a special thank you to my

advisor, Dr. Ali Shaban, the SuPER team, and to my friend Kenneth Poulter for their

knowledge and assistance.

vi

ABSTRACT

This senior project focuses on connecting together the components of the

SuPER system prototype in a safe fashion, following the National Electrical Code as

much as possible. The prototype is a design of a 12V photovoltaic system that is to

provide 400WH/day to a domestic household in a third world country.

This senior project report will discuss the system parameters and

requirements, the design and implementation of the system, and the testing of the

system connections. It also includes the wiring diagram and parts list, which is the

groundwork to be built upon in the future. In addition, this report will include

recommendations for the next generation prototype.

1

I. INTRODUCTION

The Sustainable Power for Electrical Resources (SuPER) project came to life

due to a professor who had a vision of providing electricity to people in

underdeveloped areas of the world. According to Dr. James Harris, approximately

one third of the world’s population does not have access to electrical power [1]. His

idea was to provide low-cost, sustainable power for individual households with a 20-

year life cycle [2]. Using a photovoltaic source was the most logical way to provide

this energy, because solar energy is plentiful in third world countries. The

development of this low cost photovoltaic system will take some time, but using the

Moore’s Law method, the vision will be utilized by rural families in the near future.

The SuPER system uses a photovoltaic source and a battery for energy

storage. The battery will be used to provide power when the photovoltaic cannot

provide enough alone, such as during the night or on cloudy days. The system

provides direct current (DC) power to the loads. DC power is used instead of

alternating current (AC) power, because the photovoltaic cell and battery are

inherently DC. In addition, since the system is to provide energy to a single

household, and will not be connected to a grid, long distance transmission is not

necessary. Therefore, DC to AC conversion is not required. DC power is quite

useful and practical since LED lighting is more efficient than incandescent bulbs, and

there are many appliances on the market that use DC power.

2

My senior project was to design and implement the wiring and system

protection of the SuPER system. The wiring will connect all of the system

components together. The system consists of the photovoltaic array, the DC-DC

converter, and the combiner box, switch and controller boards, all of the sensors, the

battery, and the loads.

In this report, the process of my senior project from the background, to the

requirements, design, construction, testing, and my conclusion will be discussed.

There is a wiring diagram that is included that shows how all of the components are

connected, which type of protection devices are used, and the approximate lengths of

and types of conductors used.

3

II. BACKGROUND

With the diminishing amount of fossil fuels left and the growing knowledge

plus development of solar panels, many parts of the world are using photovoltaic

sources for their power needs. People are trying to not use the power from the utility

company’s grid, but instead powering their homes with their own solar panels.

Families are even selling back power to the utility companies. Sometimes a

distributed electrical power grid is not always available to connect to, in the case of

recreational vehicles (R.V.) that connect to the grid in order to use the AC power or

invert it to DC power, when they can. In other times when the grid is not available,

they use their charged batteries for use in the coach area of the vehicle. Although,

more and more of these R.V.s now have solar panels on their roofs. This allows them

to be in rural areas and not have to depend on the grid. In addition, many of the R.V.

appliances use DC power, which makes solar power the way to go. Such appliances

include overhead lights, the furnace fan, the fan over the range, the vent fan in the

bathroom, the water pump, LP gas leak detector, stereo, and the refrigerator when it is

in the LP gas mode [3]. These R.V.s also have a power distribution system and panel

with system protection devices such as circuit breakers and fuses. There are also

companies such as SunWize Technologies that have developed a portable power

generator. This generator is a transportable source of battery power. It can generate

either AC or DC power to run small appliances like laptop computers, lights, small

4

power tools or televisions, and fans. The battery is recharged from photovoltaic

modules. This system is only meant for emergency power, farms, camping and

boating, or other like kind situations. This system also does not need fuel and

requires little maintenance [4]. This system sounds like what the SuPER project is

trying to achieve, however the system currently is retailed for $1,496. At this price,

the families we are trying to get electricity to cannot afford a system of this kind.

With the technology already in place, and will continue to develop, and as the

demand grows, the components of the system will become less expensive. That is

what we are planning for. That is where the SuPER system comes in. This system

will consist of a photovoltaic panel that will provide DC power into a DC-DC

converter that will then charge up a battery at 12-volt and provide the 12-volt to loads

such as a refrigerator, lights, a laptop computer, and a pump. The expected summary

of the daily use is noted in Table I [2]:

Table I: SUPER SYSTEM DAILY USE

Daily Source (Wh) Solar Energy Production 400Total Energy use Allocation 397 Lighting 60 Pump/motor 187 Computer/communications 100 Portable battery charging 50Energy storage: 12V AGM lead acid battery rated at 66 A h

The total cost goal of the system is to be under $500. This price includes the cost to

replace the battery every five years. This system is to have a life cycle of 20 years.

5

With this price, a family will only spend $2-3 per month, making this an affordable

system for a family in an underdeveloped country.

Since all of these systems have different components that work together, and

will be used by people to power up equipment that can be expensive, all of them need

to be wired and protected. That is what my goal was for my senior project, to do a

system wiring and protection of the SuPER system. The SuPER system’s simplified

block diagram is displayed below in Figure 1 [5]. The major parts of the system had

to be wired together following the National Electrical Code as much as possible.

Figure 1: Simplified SuPER System Block Diagram The photovoltaic panel that was used for the SuPER system was a prior

donation to the California Polytechnic State University. The panel is a BP-150SX.

6

The rated maximum power output voltage is 34.5V and rated current is 4.35A. The

battery, which is used to store the energy produced is a 12V deep cycle gel, made by

MK (MK-8G31DT). The battery that was actually purchased is rated for 98 Ah at

4.88 current draw. This is a good choice, since for a 400 Wh, 12V system, the

minimum battery capacity is 33 Ah and it is ideal to use a battery with at least double

the storage capacity required [5]. The DC-DC currently used is manufactured by

OutBack Power Systems. This will be replaced soon by a DC-DC buck converter,

designed by students. The DC-DC converter will convert the approximately 40V DC

from the solar panel to a useable 12V DC to charge up the battery and supply voltage

to the loads. The wiring to the different loads also is implemented. There were five

loads that were planned for, but only four loads were wired for. The fifth load does

have all of the equipment and protection ready for wiring. There are also some

switch printed circuit boards, a PIC, and sensor boards, which have voltage, current,

and temperature sensors on them that needed power supplied to them. The PIC is a

device that is connected to a PC, which is used to generate a PWM drive signal for a

DC-DC converter, in order to transfer energy from the photovoltaic panel to the

battery and loads. These are all of the major components of the SuPER system.

7

III. REQUIREMENTS

The goal was to link and power all of the different components of the system.

In order to achieve this goal, the different specifications of the components needed to

be tested and figured out. The most important specification was the current. This is

because these components will be connected together through conductors. Following

the NEC, conductors come in different sizes, which correspond to the ampacity they

can carry. The conductor length also comes into play for voltage drop. However, for

this system, all of the loads, meaning everything that would be wired, would be

connected within 50 feet or less of each other. The system is built on a moving cart,

therefore there would not be enough voltage lost to worry about. Therefore the

requirements were only based on the current. In discussing the other components and

their test results with the other members of the SuPER team, the currents that would

be flowing in the system were determined. These currents are listed in Table II.

Table II: SUPER SYSTEM CURRENTS

Component Current (A) Photovoltaic 4-8DC-DC Converter 15Battery 30

After having these currents determined, I had to figure out the currents for each of the

loads we were considering. These were the loads that would connect to the system

8

and use the energy that the system was providing. For these current requirements,

since we did not have the actual loads and their specifications, I looked at the system

expected daily use from Table I. Using this table and information Dr. Harris had

written in his NSF RUI proposal [6] about the expected usage time, I was able to

characterize/define some of the electrical loads. By using the following equations,

the expected currents were calculated:

][12][][

][][

][*][

VWPowerAI

WPowerheRunningTim

hHoursWWatt

=

=

The results of these calculations are in Table III below.

Table III: SUPER SYSTEM LOAD CURRENTS

Load Wh Hourscurrent

(A) Lights 60 4 1.25TV 8 1 0.67Refrigerator 50 6 0.69Pump/Motor 187 1 15.58Total 18.19

Each of these loads requires some sort of receptacle to connect to on the system cart.

These are the receptacles that the conductors would actually connect to so that they

could supply power to the terminals for a load to be plugged into. During the design

process, we also decided to research for and install components for, but not wire for, a

PC laptop. The reason we did not wire for such a laptop was that laptops run on 19V,

and not 12V. However, they are only expected to draw about 3.5A. With this

9

information, I was able to find and install the components for later use. With this

information and the information found in Table III, conductor sizes could be found

for the receptacles.

Besides finding the correct conductor to connect the system, my other

requirement was to find ways in order to protect the system. With the current

information, I was able to find the size of circuit breakers or fuses that needed to be

used. At first, I just used circuit breakers in my design. Although, after testing and

using the connected system, we found out that the circuit breakers did not act fast

enough in some situations. From this, the circuit breaker for the motor was removed

and switched out with a fuse. This fuse will act faster and help the components of the

system stay protected. In addition, all of the protection equipment that was used had

to be DC rated.

To further protect the system, the system should be grounded. Usually in DC

applications, there are only two conductors used, the positive and negative

conductors. Although, based on an article, To Ground or Not to Ground: That is Not

the Question, written by John Wiles, using a third, ground conductor, is the correct

and NEC code compliant way to protect a photovoltaic system. The system is only

then connected to a grounding electrode at one point in the system, usually in the

power center (a.k.a load center, combiner box). Therefore, all of the ground

conductors come together in the combiner box and that bus bar is connected to the

system ground. Proper grounding effectively reduces potential problems that can

result from surges and faults [7]. Reading the NEC codes, I found in article 250, that

10

for a system that is greater than 50V, but not greater than 300V, the system does not

need to be grounded [8]. Our system currently only goes up to 40V. However, in

order to ensure the safety of the people that will be handling the system and to protect

the equipment, I decided to ground the system.

11

IV. DESIGN

During the design process, the NEC Handbook was used to find as many

codes and regulations that could be found that applied to our system. However, some

codes were not followed due to cost and consideration that this is the first prototype.

The future prototypes and final product should follow all codes. These

recommendations will be mentioned in this and the conclusion sections.

The first step I took in the design process was to create a diagram that showed

where all of the parts were in the complete system. This diagram would show how

everything is connected to each other. It also showed information, such as the

expected voltage and current. The final diagram is shown in Figure 2. I decided to

use red for the positive (hot) conductor, black for the negative (neutral) conductor,

and green for the ground conductor. From there and using the currents calculated, I

used Table 310.16 from the NEC to find the conductor size for each of the

connections [8]. For most of the system we used size 10 AWG THHN/THWN

stranded copper conductor, which is rated for up to 40A. It is always a best idea to

overrate components in your system; however, this conductor size is overrated by

quite a bit. It is mainly the choice of the designer, especially when costs matter. For

the battery, although 10 AWG conductor is correctly rated, 6 AWG THHN/THWN-2

cable was used in order to best fit the connection to the terminals. For the loads,

12

however, we used 12 AWG non-metallic sheathed cable type NM-6 (romex) cable.

12 AWG copper conductor is rated for 30A. This cable type was used mainly

because they will need to be connected to the receptacles. Most receptacles fit 12

AWG conductor. Also, solid conductor, instead of stranded conductor, is normally

used due to the ease of attaching the conductor. The receptacles that I decided to use

are AC rated receptacles. There is no standard DC receptacle out in the market

currently, and the ones that are usually used are not practical or safe. The most

common receptacle is the cigarette lighter plugs, which are flimsy, and their

electrified terminals are exposed [9]. Ian Woofenden wrote in his article, “DC

Receptacles & Plugs: Unsafe Connectors?,” about there should be a standard plug for

DC applications out there. He discussed the various DC connector types out there

and stated that they are expensive, unsafe, or not as practical as the typical AC plugs.

He also mentions that the simplest and most common solution is the standard

120VAC receptacles. These are not tested or rated for DC and there is always the

possibility that someone may accidentally plug 120VAC appliances into these

receptacles that were wired for12VDC usage. He found that in these situations,

installers and homeowners rely on labels or different colored receptacles to

distinguish the receptacles. A more practical solutions, Woofenden says is using a

240VAC receptacle. These receptacles use a different configuration, as opposed to

the 120VAC receptacle, for the prongs. This is a more expensive solution, but it

allows for less confusion [9]. This article helped point me in the right direction in

deciding on which receptacles to use. It was difficult to find a 240VAC receptacle at

13

Figure 2: SuPER System Wiring Diagram

14

the time, therefore I choose to use 120VAC 15A and one 20A, used for the motor

outlet, for my design. Labeling was used to distinguish each outlet and what the

current ratings are and that the receptacles are meant for DC usage. For the loads that

we already obtained, some had to have their cords and/or plug adapters changed. The

portable DC television had a power adapter that would convert the AC power to DC

power for usage on an AC circuit. Consequently, the plug section was sliced off and

an adapter for the 15A receptacle was installed. The refrigerator and laptop (with an

adapter) had the cigarette lighter adapter. For these loads, a splitter and a cigarette

lighter adapter converter to two clamps were purchased. For this situation, the two

clamps were cut off and the conductors were connected to another 15A plug adapter.

This allowed the splitter to be connected to the converter, and the converter connected

to a receptacle. This was safe, since all of the conductors and receptacles were

overrated, the actual two loads combined would not reach the rating. This solution

worked out also because the outlet meant for the laptop had not been connected for

the first prototype. For the pump, a Dayton ¼ horsepower permanent magnet motor

(model 6MK98), was purchased in order to simulate it. This motor’s current is rated

at 21A, therefore we used 10 AWG conductor instead of the 12 AWG romex cable.

A 20A 120 VAC receptacle was used for this load however. Also, since the three

conductors were not already protected and combined in a sheath, a non-metallic type

LFNC-B conduit was used. This type of conduit is discussed in Article 356 of the

NEC. The conduit is liquid tight and flexible. In order to know what size conduit to

use, Table C.5 of the NEC is used. This table lists the type of conductor that would

15

go in the conduit and the conductor size and would then tell you what size conduit

you need for all of the conductors to fit. In our case, the ½ inch size conduit was

used. For the future prototype, all of the wiring and protection equipment storage

used should be weather resistant (UV protected and liquid tight). This means that the

conductors should be in some sort of protection, such as conduit, the entrance and exit

holes of the combiner boxes and the boxes itself should also be protected or rated for

weather resistance. In addition to creating an outlet for the motor, the motor needed a

cord to connect to this outlet receptacle. A 10 AWG, three wire cable (SJO) was used

for the cord and a 20A plug adapter was connected to the motor. The last set of wires

used is 18 AWG, which can carry 14A, for all of the circuit boards and sensors for the

system. These loads all needed to be powered up, but did not draw a lot of current.

After obtaining all of the conductors for the system, an area where all of the

conductors would go and combine had to be designed. This is also an area where the

system protection would be. Since the system is DC, these components needed to be

DC rated, and AC components could not be substituted. A PSPV Combiner Box and

circuit breakers from OutBack Power were purchased. The circuit breakers were

rated based on the currents found originally. The lights, television, and laptop are

using 10A circuit breakers. The refrigerator has a 15A breaker. The battery and

motor both have 30A circuit breakers, originally. The motor 30A circuit breaker later

was switched out with a 30A fuse for faster response time. Then an extra power bus

was connected to a 2A circuit breaker. This power bus bar is meant to power up the

circuit boards and sensors. Lastly, the photovoltaic is connected to a 10A circuit

16

breaker that is isolated from the loads power bus. This is due to the different voltages

that are involved. According to the NEC Article 720, if the voltages are less than

50V, two different voltages can be contained in the same combiner box.

In creating the design, I also had to pay attention to grounding all of the metal

enclosures. Basically, every component of the system had to have its enclosure

grounded. Then from the combiner box, the neutral bus bar had to be grounded, and

become the system ground. Once the design was together, which is Figure 2, the

construction process began. The following Figures 3, 4, and 5 show the final wired

and protected system.

Figure 3: SuPER System Combiner Box and Load Outlets

17

Figure 4: SuPER System Switchboards Junction Box

18

Figure 5: SuPER System Wiring, Rearview

19

VI. TESTING

The wiring system gets tested every time the system is turned on, since all of

the loads are now being supplied from components on the cart instead of an external

AC power source. All of the components get powered up and have not demonstrated

any abnormal behaviors, which indicate that the wiring is correct and functioning as

expected.

Further testing is done by using the DC motor. A dynamometer was installed

on the cart and connected to the motor in order to vary the torque and measure the

speed of the motor. Using the following equation, the maximum torque was found:

][1624.9

1800**1018.1)746(41

][*][*1018.1][

2

2

inlbT

Tx

rpmninlbTxWP

−=

=

−=

−

−

The rated speed of the motor, 1800 rpm, was found from the motor’s

manual/specification sheet [10]. Before this information was calculated, the motor

had been tested, by a SuPER project member, to a higher torque while connected to

the rest of the system. This caused solder on a couple of traces on the main

switchboard to melt, creating a short. The issue occurred partly due to the traces not

being able to handle large current, and because the circuit breakers did not trip. This

event led to the realization that the circuit breakers are meant only for fault currents

and work slower than fuses. Since then, the circuit breaker for the motor has

20

been replaced by a 30A fuse. Once this issue was fixed, further motor testing could

be done. Seeing as the main switchboard was still not functioning, this part of the

circuit had to be bypassed.

The motor was actually first tested isolated from the system by a SuPER

project member, in order to test if the motor was working according to specifications.

In order to perform this test, the motor was still connected to the dynamometer. A

shunt was connected in series with the motor; on the neutral conductor (the plug

adapter was disconnected). A voltmeter was connected across the shunt that

measured values in mV, with a maximum of 50mV, which corresponded to 30A.

This connection allowed the current to be measured. To find the current though,

since only voltage was measured across the shunt, the mV value found had to be

multiplied by 30A/50mV. Another voltmeter was connected across the neutral

conductor of the motor and the positive DC supply, from the school’s power lab, in

order to measure the voltage across the motor. This DC supply also was the source to

power up the motor.

Once, this configuration was connected, the torque, using the dynamometer,

was adjusted and all measurements, including the speed was collected. The results

are shown in Table IV.

21

Table IV: DC MOTOR CHARACTERISTICS

Torque [lb-in]

Speed [rpm]

Voltage [V]

Current [A]

Power [W]

Efficiency [%]

0 1840 12.26 5.1 62.526 0.0000.5 1734 11.74 6.6 77.484 13.226

1 1670 11.41 7.2 82.152 24.0281.5 1620 11.16 8.1 90.396 31.774

2 1588 11.08 9 99.72 37.6462.5 1500 10.64 9.9 105.336 42.080

3 1470 10.6 10.8 114.48 45.5333.5 1460 10.6 11.7 124.02 48.702

4 1425 10.4 12.6 131.04 51.4155 1270 9.7 15 145.5 51.5866 1140 8.9 16.2 144.18 56.0757 1060 8.7 18 156.6 56.0058 939 8.14 19.8 161.172 55.091

Figures 6 thru 10 show the effects of different parameters compared to the torque.

Motor Current Draw vs. Torque

0

5

10

15

20

25

0 2 4 6 8 10

Torque (lb-in)

Cur

rent

(am

ps)

Series1

Figure 6: Motor Current vs. Torque

22

Motor Power vs. Torque

0

2040

60

80100

120

140160

180

0 2 4 6 8 10

Torque (lb-in)

Pow

er (w

atts

)

Series1

Figure 7: Motor Power vs. Torque

Motor Speed vs. Torque

0200400600800

100012001400160018002000

0 2 4 6 8 10

Torque (lb-in)

Spee

d (r

pm)

Series1

Figure 8: Motor Speed vs. Torque

23

Motor Voltage vs. Torque

0

2

4

6

8

10

12

14

0 2 4 6 8 10

Torque (lb-in)

Volta

ge (V

)

Series1

Figure 9: Motor Voltage vs. Torque

Motor Efficiency vs. Torque

0.000

10.000

20.000

30.000

40.000

50.000

60.000

0 2 4 6 8 10

Torque (lb-in)

Effic

ienc

y (%

)

Series1

Figure 10: Motor Efficiency vs. Torque

24

These test results show that the motor is working according to specifications. This

allows us to eliminate the motor as a cause for a problem when later testing is done

on the system.

The next step in testing the motor was to use the motor while it was connected

to the SuPER system. For this case, the motor’s power is supplied from the

photovoltaic and the battery. For the most part, the connection configuration was

kept the same; however, the power supplied to the motor was now coming from the

parallel connection of the photovoltaic and the battery. An additional voltmeter was

also connected across the battery. The results from this test are in Table V.

Table V: OPERATIONAL DC MOTOR CHARACTERISTICS

Torque [lb-in]

Speed [rpm]

Voltage of

Battery [V]

Voltage of

Motor [V]

Shunt Voltage

[mV] Current

[A] Power

[W] Efficiency

[%] 0 1960 13.09 12.53 8 4.8 60.144 0.000

0.5 1925 13 12.34 10.5 6.3 77.742 14.6341 1895 12.93 12.25 12 7.2 88.2 25.396

1.5 1870 12.85 12.18 13.5 8.1 98.658 33.6062 1839 12.79 12.15 15.2 9.12 110.808 39.234

2.5 1809 12.72 12.05 16.75 10.05 121.1025 44.1413 1784 12.67 11.93 18 10.8 128.844 49.099

3.5 1760 12.64 11.86 19.5 11.7 138.762 52.4724 1719 12.5 11.78 21 12.6 148.428 54.7575 1676 12.49 11.8 24.5 14.7 173.46 57.1036 1622 12.37 11.78 27.4 16.44 193.6632 59.3987 1571 12.27 11.58 30.5 18.3 211.914 61.3388 1523 12.2 11.51 33.6 20.16 232.0416 62.064

25

Figures 11 thru 14 show the effects of different parameters compared to the torque,

while connected to the SuPER system.

Motor Current Draw vs. Torque

0

5

10

15

20

25

0 2 4 6 8 10

Torque (lb-in)

Cur

rent

(am

ps)

Series1

Figure 11: Operational Motor Current Draw vs. Torque

26

Motor Power vs. Torque

0

50

100

150

200

250

0 2 4 6 8 10

Torque (lb-in)

Pow

er (w

atts

)

Series1

Figure 12: Operational Motor Power vs. Torque

Motor Speed vs. Torque

0

500

1000

1500

2000

2500

0 2 4 6 8 10

Torque (lb-in)

Spe

ed (r

pm)

Series1

Figure 13: Operational Motor Speed vs. Torque

27

Motor Voltage vs. Torque

11.4

11.6

11.8

12

12.2

12.4

12.6

0 2 4 6 8 10

Torque (lb-in)

Volta

ge (V

)

Series1

Figure 14: Operational Motor Voltage vs. Torque

Motor Efficiency vs. Torque

0.000

10.000

20.000

30.000

40.000

50.000

60.000

70.000

0 2 4 6 8 10

Torque (lb-in)

Effic

ienc

y (%

)

Series1

Figure 15: Operational Motor Efficiency vs. Torque

28

The current draw remained pretty much the same; however the power started out

lower than before but went higher. The graph was also more linear. The speed was

faster during this test. The motor voltage was also higher than when the motor was

not connected to both the photovoltaic and battery. This affect may have occurred

due to the DC-DC converter constantly monitoring and maintaining the battery

voltage. These results tell us that when the photovoltaic is used, we are able to run

the motor at higher speeds. Figure 15 shows the speeds for the two different

conditions verses torque.

Motor Speeds vs. Torque

0

500

1000

1500

2000

2500

0 5 10

Torque (lb-in)

Spe

ed (r

pm) Operational Motor

SpeedCharacteristicMotor Speed

Figure 16: Motor Speeds vs. Torque Comparison

This conclusion is a good indication that the system works agreeably.

29

These tests prove that the motor function according to specifications and

properly and that the wiring of the system can handle the currents when the system is

operating. It also shows that the photovoltaic and battery can supply to a large load

for reasonable amount of time. This demonstrates that the SuPER system could

already be used to power loads.

30

VII. CONCLUSION AND RECOMMENDATIONS

The wiring and connection including the protection, after some renovations,

operate and function properly, and as intended. We have been able to use the system

to power up all of the loads necessary. The SuPER system no longer needs to rely on

an AC power source. Overall, the wiring and system protection is sufficient for the

first prototype.

As for recommendations for the future prototypes, the actual wiring scheme

does not have to change, however the parts used should. As mentioned earlier, all of

the parts should be protected from the environmental elements. The NEC code

should be referenced and used more. Some of the recommended codes that should be

looked at will be mentioned. Article 312 has a Table 312.6(B) that lists the minimum

wire-bending space at terminals. This table affects the conductor length that we use

due to the extra length needed to be used for the bending in and out of boxes. Article

314.16 mentions how many conductors can actually be in a box. As for entering

boxes, conduit bodies, or fittings, there are regulations for the conductors in Article

314.17. Eventually, these boxes, the combiner box and switchboard junction box,

should be manufactured by students. Articles 312.11 and 314 have construction and

installation specifications. Bus bars will need to be installed in these boxes and

Article 408.3 state how these should be arranged and supported. The system

grounding should be studied in more detail. Since the first prototype is a moving cart

31

and there is no great place to install a grounding electrode; there is no proper system

ground that the system can connect to. The article, To Ground or Not to Ground:

That is Not the Question, mentioned earlier has great information on grounding and

also refers to NEC code articles. These articles should be read in the current NEC

code book. However, overall continued research should be done in order to find more

codes and regulations that have not yet been identified.

32

VIII. BIBLIOGRAPHY

[1] Harris, James G. Graduate Seminar: Development of Sustainable Power for Electrical Resources. EE 563 Graduate Seminar presentation 9/30/05: Development of Sustainable Power for Electrical Resources – SuPER System. September 30, 2005.

[2] Harris, James G. White Paper for Sustainable Power for Electrical Resources-

SuPER. July 15, 2005. <http://www.ee.calpoly.edu/~jharris/research/super_project/white_paper_susper.pdf>

[3] Polk, Mark J. Basic RV Electricity.

<http://rveducation101.com/Articles/Basic_RV_Electricity_Savvy.pdf>. [4] SunWize Technologies. Portable Power Generator.

<http://www.sunwize.com/catalog/images/system_SW_PPG.pdf)>.

[5] Tal, Eran. SuPER System Prototype Design and Implementation. Master Thesis. San Luis Obispo: California Polytechnic State University, 2006.

[6] Harris, James G. NSF proposal. August 31, 2005.

[7] Wiles, John. To Ground or Not to Ground: That is Not the Question. Home

Power #72. August/September, 1999.

[8] Earley, Mark W., et al. NEC 2005 Handbook. 10th ed. Quincy: National Fire Protection Association, Inc., 2005.

[9] Woofenden, Ian. DC Receptacles & Plugs: Unsafe Connectors?. Home Power

#111. February/March 2006. [10] Dayton DC Motors. Operating Instructions and Parts Manual - 6MK98,

6MK99, and 6ML01 thru 6ML07.

33

Appendix A: Parts List and Costs

Table VI: PARTS LIST AND COSTS

Product

Price per unit Quantity Total

*Circuit breakers and combiner box are rated for DC usage

NEC Handbook and CD 258.75 1 258.75 2 A Circuit Breaker (Outback Power) 10.2 1 10.2 For circuit board 10 A Circuit Breaker (Outback Power) 10.2 4 40.8 PV, lights, TV, laptop 15 A Circuit Breaker (Outback Power) 10.2 1 10.2 Refrigerator

30 A Circuit Breaker (Outback Power) 10.2 2 20.4

Pump and Battery (Only one was used for Battery, Pump (motor) used fuse)

30A, 600VDC Touch Safe Fuse Holder (Outback-SGOBFH30) 18 2 36

For Motor and Battery (Only used one for Motor)

30A Midget Fuse (KTK30) 8.8 2 17.6


PSPV Combiner Box (Outback Power) 118.15 1 118.15

Service Panel/Load Center

Bus Bar kit (Outback Power) 16.15 1 16.15

For circuit board inside combiner box

15 A Outlet Receptacle 0.48 4 1.92 For Loads 20 A Outlet Receptacle 3.99 1 3.99 For pump/motor Metal Switch Box 1.57 5 7.85 Receptacle boxes Outlet Receptacle Cover 0.22 5 1.1

10/3 SJO Wire 1.26 10 12.6 To make cord for

34

motor with plug

15A connector adapter plug 1.99 2 3.98

Connector for TV and car cigarette lighter charger

20A 125V connector adapter plug 9.68 1 9.68

Connector for motor receptacle

10 AWG THHN stranded conductor (ft) 0.37 130 48.1

30 ft for Red and Black each, 70 ft for Green

6 AWG THWN-2 stranded conductor (ft) 0.68 6 4.08

3 ft for Red and Black each

20/2 Bell Conductor 0.18 35 6.3

Bell is a red and a white 20 AWG conductor, used to power up circuit boards and probes

12 AWG THHN romex non-stranded wire (ft) Donated ~35 0

From circuit breakers to receptacles

Romex connectors 1.38 4 5.52

For knockout holes in boxes

Non-metallic Conduit 0.95 10 9.5

Type LFNC-B (liquid tight), from circuit breakers to pump/motor

1/2" Conduit connectors 1.19 4 4.76

To connect conduit to combiner box and main switch box

Red Wire Connectors 1.59 1 1.59

To connect larger spliced wires

Yellow Wire Connectors 2.49 1 2.49

To connect smaller spliced wires

Cable Ties 7.92 1 7.92A large assortment of cable ties (zip ties)

1" Sticky Mount Pads for Cable Ties 1.39 1 1.39

To mount ground conductor to frame

Plywood (3/4 2x4 BC) 11.99 1 11.99

To mount panels and outlets

Lug 1 1 1 To connect ground

35

conductor to frame (had two)

Metal Junction Box 13.82 1 13.82

For Main Switch circuit board

Bushing 1.29 1 1.29For knockout holes with just conductor

Screws, washers, nuts 0.98 11 10.78

For plywood to cart, receptacles, lug, circuit boards in panel, etc.

Spacers 0.63 8 5.04

For circuit boards to be spaced in main switchboard box

Electrical Tape 1.97 3 5.91 Red, Black, Green

Plywood (3/4) 0.21 1 0.21Scrap piece to mount main switchboard

Pump 274.57 1 274.57

Dayton DC motor 6MK98, 1/4 hp, 12V, permanent magnet

Total 985.63*Prices do not include taxes or shipping

36

Appendix B: Time Schedule Allocation

Table VII: ESTIMATED TIME SCHEDULE

Estimated Time Task Hours

EE 463 Research and define connector, lead and grounding specifications 27Once SuPER cart with general components is built, implement loads on cart 27Design service panels 18Construct service panels 27Instrument cart with new service panels and ground protection 27EE 464 Research NEC for high voltage/low voltage service panel specifications 6Change service panels as needed 12Change plug adapters on all loads/get loads ready for testing 6Test loads and check wiring and ground protection 12Write Paper

37

Table VIII: ACTUAL TIME USED

Task Date Hours Notes EE 463 diagram (1st draft) 3.00 diagram (2nd draft) 2.00 diagram (3rd draft) 1.00 diagram (4th draft) 4/10/2006 2.00

Computer crashed and had to redo the changes

diagram (5th draft) 4/12/2006 1.00

Changed black conductor grounding location, changed black conductors to loads, added wall outlets to loads and grounded them

Home Depot trip 4/14/2006 1.00 Researched prices and products diagram (6th draft) 4/17/2006 2.00

Added specs, made excel sheet of products/prices

Research Load 4/20/2006 1.50

Researched 1/4 hp, 12V, permanent magnetic DC motor. Emailed company to see if could get a donation.

Installed NEC CD to computer 4/23/2006 0.50

Installed NEC CD and called tech support about installing/uninstalling for license


Added laptop load and changed pump circuit breaker from 20A to 40A. Added general bus to excel price sheet

Research Load 4/25/2006 0.50 Prices with shipping to order Figured out what to buy 4/25/2006 0.50

Figured out the lengths of conductors to buy, where to put panels, etc.

Figured out what to buy/Changed price/spec list 4/27/2006 0.75 Added items to buy, prices, notes, etc. Home Depot trip 4/28/2006 1.20 Purchased items, missing 40A single pole CB Researched NEC codes 5/1/2006 1.00

Tried to find wire stripping requirements, found other codes that should follow

Researched DC items 5/2/2006 3.50

Researched circuit breakers, panels, conductors, connections, gauges, etc.

Changed diagram a little (8th draft) 5/2/2006 2.50

Combined panels, rerouted conductors, made conductors sizes more clear

Changed diagram (9th draft), ordered items, 5/4/2006 1.50

Changed diagram to add circuit board, entered actual prices of items purchased, ordered parts/supplies

38

entered prices

Parts 5/8/2006 1.00Received parts, tried to install parts, read diagrams/instructions


Changed diagram to look more like PSPV Combiner box, moved circuit breakers and loads around

Returned items to Home Depot 5/10/2006 1.00

Returned AC circuit breakers, two AC panels, and wiring books

Home Depot trip 5/12/2006 0.75

Bought 35 ft 20 AWG/2 bell wire (red and white, used as hot and negative) to power up circuit boards and for current probes (for the other parts of the project.)


Bought UL Non-Metallic Conduit type LFNC-B (liquid tight), 1/2" plastic conduit connector, and water pipe ground clamp


Bought Carol 10/3 90 C UL water-resistant SJOOW CSA (-40C) FT-2 P-7K-123033 MSHA 300 V wire to create cable with plug for motor, screws, mount pads for zip ties, romex connectors, ground lug for PV ground conductor to metal frame

Construct panel and install load receptacles 5/14/2006 4.00

Mounted panel and receptacle boxes to wood, wired 3 loads + DC motor

Pacific Home and Garden trip 5/15/2006 1.00

Bought ground screws, receptacle plug for motor, grommets for metal punch-outs in panel, electrical tape

diagram (11th draft) and price/spec list 5/17/2006 3.00

Corrected red conductors going to and from PV and DC-to-DC converter, routed conductors for the circuit boards and probes, moved circuit board out of combiner box, added a box for conductors to run through circuit boards, ran all conductors through new box, added items/prices

Returned items to Pacific Home and Garden 5/19/2006 0.75

Exchanged receptacle plug for motor and grommets for correct ones (wrong sizes/fit)

diagram (12th draft) 5/23/2006 0.10 Added ground to switchboard metal box

39


Bought plastic rings for conductors to go through instead of grommets, electrical tape, asked about metal box for switchboards, tried to find plug to fit SO cable for motor

misc. store trips 4.50


Changed the diagram, conductors needed to be removed/reversed from the pv to dc-to-dc converter

Installation/Wired cart 6/4/2006 13.00

Installed switchboard box, wired everything up


Changed diagram after installation, removed some conductors from switchboard box, added ground conductor from PV again, changed some conductor specs

Prices 6/6/2006 Added prices, deleted items EE 464 Found NEC code for two different voltages in one combiner box 1.00 Art 720 Bought 15A plug adapter for DC TV 10/10/06 0.50 Worked on diagram (15th draft) 10/12/06 0.50 changed 1A circuit breaker to 2A Worked on cleaning up the wires on the cart and got 2 prong adapter installed for TV and for car charger 10/17/06 4.00 Cleaned up wires on the cart 10/18//06 1.00 Researched and purchased fuses 4.00 Installed fuse for motor 11/1/06 1.00 Ran motor test 11/7/06 3.00 With Solar Power and Battery Diagram (16th draft) 11/10/06 0.50

Changed the 30A Circuit Breaker for the motor to a 30A Fuse

40

Prices 11/10/06 0.50 Added items on price list Total 79.80

*Since many of the tasks fell into multiple categories picked for estimation, the actual tasks were not categorized.

41

Analysis of Senior Project Design

Summary of Functional Requirements: The SuPER system is to provide DC

electricity to a small family unit in an underdeveloped country. My portion of the

project is to wire the system together and provide system protection.

Primary Constraints: The main constraint for this project was the knowledge of the

National Electrical Codes. Having access to the codes were not the issue, but

knowing what to look for and how to understand the code is difficult. Unless I had

prior knowledge of certain codes and regulations, I would not have known to look for

them in the NEC. Other constraints were having the skills to easily assemble the

system. Power tools had to be used, and some tasks needed strength. The

construction of the project could have been done, however the ease and amount of

time spent would be varied according to prior skill level.

Economic: The estimated cost for the components of my project is listed in the

following table:

Estimate Circuit Breakers and Panels were all AC rated

Product Price per

unit Quantity Total Notes

Product Price per

unit Quantity Total NEC 300 1 300 15 A Circuit Breaker 3.19 4 12.76 3 Loads, 1 Panel for PV 20 A Circuit Breaker 2.99 1 2.99 1 Load 40 A Circuit Breaker 8.7 2 17.4 Pump and Battery

42

6 space outdoor 100A panel 22.49 1 22.49 Service Panel 2 space outdoor 70A panel 19.97 1 19.97 Panel for PV 4 ground bar (bus) 4.27 1 4.27 for DC-to-DC converter Outlets 0.5 6 3 for Loads 10 AWG wire (single wires) 0.9 130 117


6 AWG wire (estimate per foot) 0.9 6 5.4 3 ft for Red and Black each Plywood (30 x 18) 1 0 To mount panels and outlets 8 ft Ground Rod 1

Screws For plywood to cart, onto plywood, ground screw?

Water Pipe Clamp (Ground Rod) 3.52 1 3.52

Clamp onto water pipe to substitute ground rod

Pump 274.57 1 274.57Dayton DC motor 6MK98, 1/4 hp, 12V, permanent magnet

Total 783.37

However, the estimated prices were for AC rated components and not DC rated.

Also, as the construction went on, many more items needed to be purchased to put the

system together. The actual products purchased and prices are listed in the following

table:

43

Actual

Product Price

per unit Quantity Total

*Circuit breakers and combiner box are rated for DC usage

NEC Handbook and CD 258.75 1 258.75 2 A Circuit Breaker (Outback Power) 10.2 1 10.2 For circuit board 10 A Circuit Breaker (Outback Power) 10.2 4 40.8 PV, lights, tv, laptop 15 A Circuit Breaker (Outback Power) 10.2 1 10.2 Refrigerator

30 A Circuit Breaker (Outback Power) 10.2 2 20.4

Pump and Battery (Only one was used for Battery, Pump (motor) used fuse)

30A, 600VDC Touch Safe Fuse Holder (Outback-SGOBFH30) 18 2 36


30A Midget Fuse (KTK30) 8.8 2 17.6


PSPV Combiner Box (Outback Power) 118.15 1 118.15

Service Panel/Load Center

Bus Bar kit (Outback Power) 16.15 1 16.15

For circuit board inside combiner box

15 A Outlet Receptacle 0.48 4 1.92 For Loads 20 A Outlet Receptacle 3.99 1 3.99 For pump/motor Metal Switch Box 1.57 5 7.85 Receptacle boxes Outlet Receptacle Cover 0.22 5 1.1

10/3 SJO Wire 1.26 10 12.6To make cord for motor with plug

15A connector adapter plug 1.99 2 3.98

Connector for TV and car cigarette lighter charger

20A 125V connector adapter plug 9.68 1 9.68

Connector for motor receptacle

10 AWG THHN stranded wire (ft) 0.37 130 48.1


6 AWG THWN-2 stranded wire (ft) 0.68 6 4.08

3 ft for Red and Black each

20/2 Bell Wire 0.18 35 6.3

Bell is a red and a white 20 AWG wire, used to power up circuit boards and probes

12 AWG THHN romex non-stranded Donated ~35 0

From circuit breakers to receptacles

44

wire (ft)

Romex connectors 1.38 4 5.52For knockout holes in boxes

Non-metallic Conduit 0.95 10 9.5

Type LFNC-B (liquid tight), from circuit breakers to pump/motor

1/2" Conduit connectors 1.19 4 4.76

To connect conduit to combiner box and main switch box

Red Wire Connectors 1.59 1 1.59

To connect larger split wires

Yellow Wire Connectors 2.49 1 2.49

To connect smaller split wires

Cable Ties 7.92 1 7.92A large assortment of cable ties (zip ties)

1" Sticky Mount Pads for Cable Ties 1.39 1 1.39

To mount ground wire to frame

Plywood (3/4 2x4 BC) 11.99 1 11.99

To mount panels and outlets

Lug 1 1 1To connect ground wire to frame (had two)

Metal Junction Box 13.82 1 13.82For Main Switch circuit board

Bushing 1.29 1 1.29For knockout holes with just wire

Screws, washers, nuts 0.98 11 10.78

For plywood to cart, receptacles, lug, circuit boards in panel, etc.

Spacers 0.63 8 5.04

For circuit boards to be spaced in main switchboard box

Electrical Tape 1.97 3 5.91 Red, Black, Green

Plywood (3/4) 0.21 1 0.21Scrap piece to mount main switchboard

Pump 274.57 1 274.57

Dayton DC motor 6MK98, 1/4 hp, 12V, permanent magnet

Total 985.63

For the estimated time, I believe that I estimated more time for certain tasks than it

actually took and not enough time for tasks that ended up taking longer. My

estimated times are listed in the following table:

45

Estimated Time Task Hours

EE 463

Research and define connector, lead and grounding specifications 27

Once SuPER cart with general components is built, implement loads on cart 27

Design service panels 18

Construct service panels 27

Instrument cart with new service panels and ground protection 27 EE 464

Research NEC for high voltage/low voltage service panel specifications 6

Change service panels as needed 12

Change plug adapters on all loads/get loads ready for testing 6

Test loads and check wiring and ground protection 12 Write Paper

The actual time was difficult to categorize as I had done for the estimation, due to the

fact that many of the tasks occurred at the same time or had to do with each other.

Therefore, my actual time is a total of the time spent, and is shown in the following

table:

46

Task Date Hours Notes EE 463 diagram (1st draft) 3.00 diagram (2nd draft) 2.00 diagram (3rd draft) 1.00 diagram (4th draft) 4/10/2006 2.00 Computer crashed and had to redo the changes


Changed black wire grounding location, changed black wires to loads, added wall outlets to loads and grounded them

Home Depot trip 4/14/2006 1.00 Researched prices and products diagram (6th draft) 4/17/2006 2.00 Added specs, made excel sheet of products/prices

Research Load 4/20/2006 1.50

Researched 1/4 hp, 12V, permanent magnetic DC motor. Emailed company to see if could get a donation.

Installed NEC CD to computer 4/23/2006 0.50

Installed NEC CD and called tech support about installing/uninstalling for license


Added laptop load and changed pump circuit breaker from 20A to 40A. Added general bus to excel price sheet

Research Load 4/25/2006 0.50 Prices with shipping to order Figured out what to buy 4/25/2006 0.50

Figured out the lengths of wires to buy, where to put panels, etc.

Figured out what to buy/Changed price/spec list 4/27/2006 0.75 Added items to buy, prices, notes, etc. Home Depot trip 4/28/2006 1.20 Purchased items, missing 40A single pole CB Researched NEC codes 5/1/2006 1.00

Tried to find wire stripping requirements, found other codes that should follow

Researched DC items 5/2/2006 3.50

Researched circuit breakers, panels, wires, connections, gauges, etc.

Changed diagram a little (8th draft) 5/2/2006 2.50

Combined panels, rerouted wires, made wires sizes more clear

Changed diagram (9th draft), ordered items, entered prices 5/4/2006 1.50

Changed diagram to add circuit board, entered actual prices of items purchased, ordered parts/supplies

Parts 5/8/2006 1.00Received parts, tried to install parts, read diagrams/instructions


Changed diagram to look more like PSPV Combiner box, moved circuit breakers and loads around

Returned items to Home Depot 5/10/2006 1.00

Returned AC circuit breakers, two AC panels, and wiring books


Bought 35 ft 20 AWG/2 bell wire (red and white, used as hot and negative) to power up circuit boards and for current probes (for the other parts of the project.)

47


Bought UL Non-Metallic Conduit type LFNC-B (liquid tight), 1/2" plastic conduit connector, and water pipe ground clamp


Bought Carol 10/3 90 C UL water-resistant SJOOW CSA (-40C) FT-2 P-7K-123033 MSHA 300 V wire to create cable with plug for motor, screws, mount pads for zip ties, romex connectors, ground lug for PV ground wire to metal frame

Construct panel and install load receptacles 5/14/2006 4.00

Mounted panel and receptacle boxes to wood, wired 3 loads + DC motor

Pacific Home and Garden trip 5/15/2006 1.00

Bought ground screws, receptacle plug for motor, grommets for metal punch-outs in panel, electrical tape

diagram (11th draft) and price/spec list 5/17/2006 3.00

Corrected red wires going to and from PV and DC-to-DC converter, routed wires for the circuit boards and probes, moved circuit board out of combiner box, added a box for wires to run through circuit boards, ran all wires through new box, added items/prices

Returned items to Pacific Home and Garden 5/19/2006 0.75

Exchanged receptacle plug for motor and grommets for correct ones (wrong sizes/fit)

diagram (12th draft) 5/23/2006 0.10 Added ground to switch board metal box


Bought plastic rings for wires to go through instead of grommets, electrical tape, asked about metal box for switch boards, tried to find plug to fit SO cable for motor

misc. store trips 4.50 diagram (13th draft) 5/30/2006 1.00

Changed the diagram, wires needed to be removed/reversed from the pv to dc-to-dc converter

Installation/Wired cart 6/4/2006 13.00 Installed switchboard box, wired everything up


Changed diagram after installation, removed some wires from switchboard box, added ground wire from PV again, changed some wire specs

Prices 6/6/2006 Added prices, deleted items EE 464

Found NEC code for two different voltages in one combiner box 1.00 Art 720 Bought 15A plug adapter for DC tv 10/10/06 0.50 Worked on diagram (15th draft) 10/12/06 0.50 changed 1A circuit breaker to 2A

48

Worked on cleaning up the wires on the cart and got 2 prong adapter installed for tv and for car charger 10/17/06 4.00 Cleaned up wires on the cart 10/18//06 1.00 Researched and purchased fuses 4.00 Installed fuse for motor 11/1/06 1.00 Ran motor test 11/7/06 3.00 With Solar Power and Battery Diagram (16th draft) 11/10/06 0.50

Changed the 30A Circuit Breaker for the motor to a 30A Fuse

Prices 11/10/06 0.50 Added items on price list Total 79.80

If Manufactured on a commercial basis: The end product is estimated at around

$500 per unit for a life cycle of 20 years. This price also includes the replacement

battery every five years. Purchase price and the number of units sold per year are yet

to be determined. However, the estimated profit per year is about 5-10% of the

investment.

Environmental: This system is a photovoltaic power supply system, therefore should

be safe for the environment. The only part of our system that could be an

environmental impact is the battery when it is disposed of. The battery has to be

disposed of correctly and safely.

Manufacturability: The portion of the project that I am responsible for is possible to

manufacture and would not be difficult. However, manufacturing all of the

components, such as the conductors and circuit breakers or fuses, may not be cost

effective. The combiner box and switchboard junction boxes should be manufactured

49

though. I believe that these components are easy to manufacture and will cost less

than to purchase.

Sustainability: This project is very sustainable. The system is estimated to have a 20

year life cycle with little maintenance, besides replacing the battery every five years.

The system is also using a sustainable form of energy. As for future upgrades, the

final product will be of modular design, making the upgrades easy to do.

Ethical: This project is meant to provide power to families in underdeveloped

countries that currently do not have electricity. It also is not meant to make a large

profit; therefore this project is very ethical.

Health and Safety: Once the final design is manufactured, following all of the NEC

codes, this system should be safe for any person to use. The system does have current

flowing; therefore, users should be cautious when handling it. If users are being safe

around the system, then there are no other health and safety concerns.

Social and Political: The impact that this system will have to the families in

underdeveloped countries is huge. The families will not be able to use light at night

in order to work or read and get a better education. Also, they will be able to pump

clean water to use and refrigerate their vaccines or food. This will end up helping the

social and political state of these countries.

Development: This project taught me about DC systems and more about renewable

energy. I also learned how to use the NEC and got a better understanding of

grounding. Overall, I learned a lot of information about a power system by being

50

able to apply what I learned in school and finding out about what is used out in the

real world.

Documents

SuPER PROJECT WIRING AND SYSTEM …jharris/research/...SuPER PROJECT WIRING AND SYSTEM PROTECTION by Jennifer Cao Senior Project ELECTRICAL ENGINEERING DEPARTMENT California Polytechnic