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 20year 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
Solar Energy Production
Total Energy use Allocation
Lighting
Pump/motor
Computer/communications
Portable battery charging
Energy storage: 12V AGM lead acid battery rated at 66 A h
(Wh)
400
397
60
187
100
50
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
Photovoltaic
DC-DC
Converter
Battery
Current (A)
4-8
15
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:
Watt[W ] * Hours[h]
= Power[W ]
RunningTime[h]
Power[W ]
I [ A] =
12[V ]
The results of these calculations are in Table III below.
Table III: SUPER SYSTEM LOAD CURRENTS
Load
Wh Hours
Lights
60
4
TV
8
1
Refrigerator
50
6
Pump/Motor 187
1
Total
current
(A)
1.25
0.67
0.69
15.58
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:
P[W ] = 1.18 x10 −2 * T [lb − in] * n[rpm]
1
(746) = 1.18 x10 − 2 * T *1800
4
T = 9.1624[lb − in]
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]
0
0.5
1
1.5
2
2.5
3
3.5
4
5
6
7
8
Speed
[rpm]
1840
1734
1670
1620
1588
1500
1470
1460
1425
1270
1140
1060
939
Voltage
[V]
12.26
11.74
11.41
11.16
11.08
10.64
10.6
10.6
10.4
9.7
8.9
8.7
8.14
Current
[A]
5.1
6.6
7.2
8.1
9
9.9
10.8
11.7
12.6
15
16.2
18
19.8
Power Efficiency
[%]
[W]
62.526
0.000
77.484
13.226
82.152
24.028
90.396
31.774
99.72
37.646
105.336
42.080
114.48
45.533
124.02
48.702
131.04
51.415
145.5
51.586
144.18
56.075
156.6
56.005
161.172
55.091
Figures 6 thru 10 show the effects of different parameters compared to the torque.
Motor Current Draw vs. Torque
25
Current (amps)
20
15
Series1
10
5
0
0
2
4
6
8
10
Torque (lb-in)
Figure 6: Motor Current vs. Torque
22
Motor Power vs. Torque
180
160
Power (watts)
140
120
100
Series1
80
60
40
20
0
0
2
4
6
8
10
Torque (lb-in)
Figure 7: Motor Power vs. Torque
Motor Speed vs. Torque
2000
Speed (rpm)
1800
1600
1400
1200
Series1
1000
800
600
400
200
0
0
2
4
6
8
10
Torque (lb-in)
Figure 8: Motor Speed vs. Torque
23
Motor Voltage vs. Torque
14
12
Voltage (V)
10
8
Series1
6
4
2
0
0
2
4
6
8
10
Torque (lb-in)
Figure 9: Motor Voltage vs. Torque
Motor Efficiency vs. Torque
60.000
Efficiency (%)
50.000
40.000
Series1
30.000
20.000
10.000
0.000
0
2
4
6
8
10
Torque (lb-in)
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]
0
0.5
1
1.5
2
2.5
3
3.5
4
5
6
7
8
Speed
[rpm]
1960
1925
1895
1870
1839
1809
1784
1760
1719
1676
1622
1571
1523
Voltage Voltage
Shunt
of
of
Battery Motor Voltage
[V]
[V]
[mV]
13.09
12.53
8
13
12.34
10.5
12.93
12.25
12
12.85
12.18
13.5
12.79
12.15
15.2
12.72
12.05
16.75
12.67
11.93
18
12.64
11.86
19.5
12.5
11.78
21
12.49
11.8
24.5
12.37
11.78
27.4
12.27
11.58
30.5
12.2
11.51
33.6
Current
Power Efficiency
[A]
[W]
[%]
4.8
60.144
0.000
6.3
77.742
14.634
7.2
88.2
25.396
8.1
98.658
33.606
9.12 110.808
39.234
10.05 121.1025
44.141
10.8 128.844
49.099
11.7 138.762
52.472
12.6 148.428
54.757
14.7
173.46
57.103
16.44 193.6632
59.398
18.3 211.914
61.338
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
25
Current (amps)
20
15
Series1
10
5
0
0
2
4
6
8
10
Torque (lb-in)
Figure 11: Operational Motor Current Draw vs. Torque
26
Motor Power vs. Torque
250
Power
(watts)
200
150
Series1
100
50
0
0
2
4
6
8
10
Torque (lb-in)
Figure 12: Operational Motor Power vs. Torque
Motor Speed vs. Torque
2500
Speed (rpm)
2000
1500
Series1
1000
500
0
0
2
4
6
8
10
Torque (lb-in)
Figure 13: Operational Motor Speed vs. Torque
27
Motor Voltage vs. Torque
12.6
Voltage (V)
12.4
12.2
12
Series1
11.8
11.6
11.4
0
2
4
6
8
10
Torque (lb-in)
Figure 14: Operational Motor Voltage vs. Torque
Motor Efficiency vs. Torque
70.000
Efficiency (%)
60.000
50.000
40.000
Series1
30.000
20.000
10.000
0.000
0
2
4
6
8
10
Torque (lb-in)
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
2500
Speed (rpm)
2000
1500
Operational Motor
Speed
1000
Characteristic
Motor Speed
500
0
0
5
10
Torque (lb-in)
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 ResourcesSuPER. July 15, 2005.
<http://www.ee.calpoly.edu/~jharris/research/super_project/white_paper_susp
er.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
NEC Handbook
and CD
2 A Circuit
Breaker (Outback
Power)
10 A Circuit
Breaker (Outback
Power)
15 A Circuit
Breaker (Outback
Power)
30 A Circuit
Breaker (Outback
Power)
30A, 600VDC
Touch Safe Fuse
Holder (OutbackSGOBFH30)
30A Midget Fuse
(KTK30)
PSPV Combiner
Box (Outback
Power)
Bus Bar kit
(Outback Power)
15 A Outlet
Receptacle
20 A Outlet
Receptacle
Metal Switch Box
Outlet Receptacle
Cover
10/3 SJO Wire
Price
per
unit
258.75
Quantity
Total
*Circuit breakers and
combiner box are
rated for DC usage
1 258.75
10.2
1
10.2 For circuit board
10.2
4
40.8 PV, lights, TV, laptop
10.2
1
10.2
2
10.2 Refrigerator
Pump and Battery
(Only one was used
for Battery, Pump
20.4 (motor) used fuse)
18
2
8.8
2
118.15
16.15
For Motor and Battery
(Only used one for
36 Motor)
For Motor and Battery
(Only used one for
17.6 Motor)
Service Panel/Load
1 118.15 Center
For circuit board
1 16.15 inside combiner box
0.48
4
1.92 For Loads
3.99
1.57
1
5
3.99 For pump/motor
7.85 Receptacle boxes
0.22
5
1.26
10
1.1
12.6 To make cord for
34
motor with plug
15A connector
adapter plug
20A 125V
connector adapter
plug
10 AWG THHN
stranded
conductor (ft)
6 AWG THWN-2
stranded
conductor (ft)
20/2 Bell
Conductor
12 AWG THHN
romex nonstranded wire (ft)
Romex
connectors
Non-metallic
Conduit
1/2" Conduit
connectors
Red Wire
Connectors
Yellow Wire
Connectors
Cable Ties
1" Sticky Mount
Pads for Cable
Ties
Plywood (3/4 2x4
BC)
Lug
1.99
2
9.68
1
0.37
130
0.68
6
0.18
35
Donated
~35
1.38
4
0.95
10
1.19
4
1.59
1
2.49
1
7.92
1
1.39
1
11.99
1
1
1
Connector for TV and
car cigarette lighter
3.98 charger
Connector for motor
9.68 receptacle
30 ft for Red and
Black each, 70 ft for
48.1 Green
3 ft for Red and Black
4.08 each
Bell is a red and a
white 20 AWG
conductor, used to
power up circuit
6.3 boards and probes
From circuit breakers
0 to receptacles
For knockout holes in
5.52 boxes
Type LFNC-B (liquid
tight), from circuit
breakers to
9.5 pump/motor
To connect conduit to
combiner box and
4.76 main switch box
To connect larger
1.59 spliced wires
To connect smaller
2.49 spliced wires
A large assortment of
7.92 cable ties (zip ties)
To mount ground
1.39 conductor to frame
To mount panels and
11.99 outlets
1 To connect ground
35
Metal Junction
Box
13.82
1
13.82
Bushing
1.29
1
1.29
Screws, washers,
nuts
0.98
11
10.78
Spacers
Electrical Tape
0.63
1.97
8
3
5.04
5.91
Plywood (3/4)
0.21
1
0.21
Pump
Total
274.57
1 274.57
985.63
conductor to frame
(had two)
For Main Switch
circuit board
For knockout holes
with just conductor
For plywood to cart,
receptacles, lug,
circuit boards in
panel, etc.
For circuit boards to
be spaced in main
switchboard box
Red, Black, Green
Scrap piece to mount
main switchboard
Dayton DC motor
6MK98, 1/4 hp, 12V,
permanent magnet
*Prices do not include
taxes or shipping
36
Appendix B: Time Schedule Allocation
Table VII: ESTIMATED TIME SCHEDULE
Estimated Time
Task
EE 463
Research and define
connector, lead and
grounding
specifications
Once SuPER cart
with general
components is built,
implement loads on
cart
Design service panels
Construct service
panels
Instrument cart with
new service panels
and ground
protection
EE 464
Research NEC for
high voltage/low
voltage service panel
specifications
Change service
panels as needed
Change plug adapters
on all loads/get loads
ready for testing
Test loads and check
wiring and ground
protection
Write Paper
Hours
27
27
18
27
27
6
12
6
12
37
Table VIII: ACTUAL TIME USED
Task
EE 463
diagram (1st
draft)
diagram (2nd
draft)
diagram (3rd
draft)
diagram (4th
draft)
diagram (5th
draft)
Home Depot trip
diagram (6th
draft)
Research Load
Installed NEC
CD to computer
diagram (7th
draft)
Research Load
Figured out what
to buy
Figured out what
to buy/Changed
price/spec list
Home Depot trip
Researched NEC
codes
Researched DC
items
Changed diagram
a little (8th draft)
Changed diagram
(9th draft),
ordered items,
Date
Hours
Notes
3.00
2.00
1.00
4/10/2006
4/12/2006
4/14/2006
4/17/2006
4/20/2006
4/23/2006
4/24/2006
4/25/2006
4/25/2006
4/27/2006
4/28/2006
Computer crashed and had to redo the
2.00 changes
Changed black conductor grounding location,
changed black conductors to loads, added wall
1.00 outlets to loads and grounded them
1.00 Researched prices and products
Added specs, made excel sheet of
2.00 products/prices
Researched 1/4 hp, 12V, permanent magnetic
DC motor. Emailed company to see if could
1.50 get a donation.
Installed NEC CD and called tech support
0.50 about installing/uninstalling for license
Added laptop load and changed pump circuit
breaker from 20A to 40A. Added general bus
1.50 to excel price sheet
0.50 Prices with shipping to order
Figured out the lengths of conductors to buy,
0.50 where to put panels, etc.
5/2/2006
0.75 Added items to buy, prices, notes, etc.
1.20 Purchased items, missing 40A single pole CB
Tried to find wire stripping requirements,
1.00 found other codes that should follow
Researched circuit breakers, panels,
3.50 conductors, connections, gauges, etc.
Combined panels, rerouted conductors, made
2.50 conductors sizes more clear
5/4/2006
Changed diagram to add circuit board, entered
actual prices of items purchased, ordered
1.50 parts/supplies
5/1/2006
5/2/2006
38
entered prices
Parts
5/8/2006
diagram (10th
draft)
Returned items to
Home Depot
5/10/2006
Home Depot trip
5/12/2006
Home Depot trip
5/13/2006
Home Depot trip
Construct panel
and install load
receptacles
5/14/2006
5/14/2006
Pacific Home and
Garden trip
5/15/2006
diagram (11th
draft) and
price/spec list
Returned items to
Pacific Home and
Garden
diagram (12th
draft)
5/8/2006
Received parts, tried to install parts, read
1.00 diagrams/instructions
Changed diagram to look more like PSPV
Combiner box, moved circuit breakers and
2.75 loads around
Returned AC circuit breakers, two AC panels,
1.00 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
0.75 other parts of the project.)
Bought UL Non-Metallic Conduit type
LFNC-B (liquid tight), 1/2" plastic conduit
1.00 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
1.50 conductor to metal frame
5/17/2006
Mounted panel and receptacle boxes to wood,
4.00 wired 3 loads + DC motor
Bought ground screws, receptacle plug for
motor, grommets for metal punch-outs in
1.00 panel, electrical tape
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
3.00 box, added items/prices
5/19/2006
Exchanged receptacle plug for motor and
0.75 grommets for correct ones (wrong sizes/fit)
5/23/2006
0.10 Added ground to switchboard metal box
39
Home Depot trip
misc. store trips
5/19/2006
diagram (13th
draft)
5/30/2006
Installation/Wired
cart
6/4/2006
diagram (14th
draft)
Prices
EE 464
Found NEC code
for two different
voltages in one
combiner box
Bought 15A plug
adapter for DC
TV
Worked on
diagram (15th
draft)
Worked on
cleaning up the
wires on the cart
and got 2 prong
adapter installed
for TV and for
car charger
Cleaned up wires
on the cart
Researched and
purchased fuses
Installed fuse for
motor
Ran motor test
Diagram (16th
draft)
6/6/2006
6/6/2006
Bought plastic rings for conductors to go
through instead of grommets, electrical tape,
asked about metal box for switchboards, tried
1.00 to find plug to fit SO cable for motor
4.50
Changed the diagram, conductors needed to
be removed/reversed from the pv to dc-to-dc
1.00 converter
Installed switchboard box, wired everything
13.00 up
Changed diagram after installation, removed
some conductors from switchboard box,
added ground conductor from PV again,
0.50 changed some conductor specs
Added prices, deleted items
1.00 Art 720
10/10/06
0.50
10/12/06
0.50 changed 1A circuit breaker to 2A
10/17/06
4.00
10/18//06
1.00
4.00
11/1/06
11/7/06
11/10/06
1.00
3.00 With Solar Power and Battery
Changed the 30A Circuit Breaker for the
0.50 motor to a 30A Fuse
40
Prices
Total
11/10/06
0.50 Added items on price list
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:
Circuit Breakers and Panels were all AC
rated
Estimate
Product
Product
NEC
15 A
Circuit
Breaker
20 A
Circuit
Breaker
40 A
Circuit
Breaker
Price per
unit
Price per
unit
300
Quantity
Total
Notes
Quantity
1
Total
300
3.19
4
12.76
2.99
1
2.99
1 Load
8.7
2
17.4
Pump and Battery
3 Loads, 1 Panel for PV
42
6 space
outdoor
100A
panel
2 space
outdoor
70A panel
4 ground
bar (bus)
Outlets
10 AWG
wire
(single
wires)
6 AWG
wire
(estimate
per foot)
Plywood
(30 x 18)
8 ft
Ground
Rod
Screws
Water
Pipe
Clamp
(Ground
Rod)
Pump
Total
22.49
1
22.49
Service Panel
19.97
1
19.97
Panel for PV
4.27
0.5
1
6
4.27
3
for DC-to-DC converter
for Loads
0.9
130
117
30 ft for Red and Black each, 70 ft for
Green
0.9
6
5.4
3 ft for Red and Black each
1
0
To mount panels and outlets
1
For plywood to cart, onto plywood, ground
screw?
3.52
1
3.52
274.57
1
274.57
783.37
Clamp onto water pipe to substitute
ground rod
Dayton DC motor 6MK98, 1/4 hp, 12V,
permanent magnet
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
NEC Handbook and
CD
2 A Circuit Breaker
(Outback Power)
10 A Circuit Breaker
(Outback Power)
15 A Circuit Breaker
(Outback Power)
30 A Circuit Breaker
(Outback Power)
30A, 600VDC Touch
Safe Fuse Holder
(OutbackSGOBFH30)
30A Midget Fuse
(KTK30)
PSPV Combiner Box
(Outback Power)
Bus Bar kit (Outback
Power)
15 A Outlet
Receptacle
20 A Outlet
Receptacle
Metal Switch Box
Outlet Receptacle
Cover
10/3 SJO Wire
15A connector
adapter plug
20A 125V connector
adapter plug
10 AWG THHN
stranded wire (ft)
6 AWG THWN-2
stranded wire (ft)
20/2 Bell Wire
12 AWG THHN
romex non-stranded
*Circuit breakers and
combiner box are rated
for DC usage
Price
per unit
Quantity
258.75
1
258.75
10.2
1
10.2
For circuit board
10.2
4
40.8
PV, lights, tv, laptop
10.2
1
10.2
Refrigerator
Pump and Battery (Only
one was used for Battery,
Pump (motor) used fuse)
Total
10.2
2
20.4
18
2
36
8.8
2
17.6
118.15
1
118.15
16.15
1
16.15
0.48
4
1.92
For Loads
3.99
1.57
1
5
3.99
7.85
For pump/motor
Receptacle boxes
0.22
5
1.1
1.26
10
12.6
1.99
2
3.98
9.68
1
9.68
0.37
130
48.1
0.68
6
4.08
0.18
35
6.3
Donated
~35
0
For Motor and Battery
(Only used one for Motor)
For Motor and Battery
(Only used one for Motor)
Service Panel/Load
Center
For circuit board inside
combiner box
To make cord for motor
with plug
Connector for TV and car
cigarette lighter charger
Connector for motor
receptacle
30 ft for Red and Black
each, 70 ft for Green
3 ft for Red and Black
each
Bell is a red and a white
20 AWG wire, used to
power up circuit boards
and probes
From circuit breakers to
receptacles
44
wire (ft)
Romex connectors
Non-metallic Conduit
1/2" Conduit
connectors
Red Wire
Connectors
Yellow Wire
Connectors
Cable Ties
1" Sticky Mount
Pads for Cable Ties
Plywood (3/4 2x4
BC)
Lug
Metal Junction Box
Bushing
Screws, washers,
nuts
1.38
0.95
4
5.52
10
9.5
1.19
4
4.76
1.59
1
1.59
2.49
1
2.49
7.92
1
7.92
1.39
1
1.39
11.99
1
11.99
1
1
1
13.82
1
13.82
1.29
1
1.29
0.98
11
10.78
Spacers
Electrical Tape
0.63
1.97
8
3
5.04
5.91
Plywood (3/4)
0.21
1
0.21
274.57
1
274.57
985.63
Pump
Total
For knockout holes in
boxes
Type LFNC-B (liquid
tight), from circuit
breakers to pump/motor
To connect conduit to
combiner box and main
switch box
To connect larger split
wires
To connect smaller split
wires
A large assortment of
cable ties (zip ties)
To mount ground wire to
frame
To mount panels and
outlets
To connect ground wire to
frame (had two)
For Main Switch circuit
board
For knockout holes with
just wire
For plywood to cart,
receptacles, lug, circuit
boards in panel, etc.
For circuit boards to be
spaced in main
switchboard box
Red, Black, Green
Scrap piece to mount
main switchboard
Dayton DC motor 6MK98,
1/4 hp, 12V, permanent
magnet
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
EE 464
27
Research NEC for high voltage/low voltage service
panel specifications
Change service panels as needed
Change plug adapters on all loads/get loads ready for
testing
Test loads and check wiring and ground protection
Write Paper
6
12
6
12
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
EE 463
diagram (1st draft)
diagram (2nd
draft)
diagram (3rd draft)
diagram (4th draft)
Date
Hours
3.00
4/10/2006
2.00
1.00
2.00
diagram (5th draft)
Home Depot trip
diagram (6th draft)
4/12/2006
4/14/2006
4/17/2006
1.00
1.00
2.00
Research Load
Installed NEC CD
to computer
4/20/2006
1.50
4/23/2006
0.50
diagram (7th draft)
Research Load
Figured out what
to buy
Figured out what
to buy/Changed
price/spec list
Home Depot trip
Researched NEC
codes
Researched DC
items
Changed diagram
a little (8th draft)
Changed diagram
(9th draft), ordered
items, entered
prices
Notes
4/24/2006
4/25/2006
1.50
0.50
4/25/2006
0.50
4/27/2006
4/28/2006
0.75
1.20
5/1/2006
1.00
5/2/2006
3.50
5/2/2006
2.50
5/4/2006
1.50
5/8/2006
1.00
Parts
diagram (10th
draft)
Returned items to
Home Depot
5/8/2006
2.75
5/10/2006
1.00
Home Depot trip
5/12/2006
0.75
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
Researched prices and products
Added specs, made excel sheet of products/prices
Researched 1/4 hp, 12V, permanent magnetic DC
motor. Emailed company to see if could get a
donation.
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
Prices with shipping to order
Figured out the lengths of wires to buy, where to put
panels, etc.
Added items to buy, prices, notes, etc.
Purchased items, missing 40A single pole CB
Tried to find wire stripping requirements, found other
codes that should follow
Researched circuit breakers, panels, wires,
connections, gauges, etc.
Combined panels, rerouted wires, made wires sizes
more clear
Changed diagram to add circuit board, entered
actual prices of items purchased, ordered
parts/supplies
Received parts, tried to install parts, read
diagrams/instructions
Changed diagram to look more like PSPV Combiner
box, moved circuit breakers and loads around
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.)
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Home Depot trip
5/13/2006
1.00
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
Home Depot trip
5/14/2006
1.50
Construct panel
and install load
receptacles
5/14/2006
4.00
Pacific Home and
Garden trip
5/15/2006
1.00
diagram (11th
draft) and
price/spec list
5/17/2006
3.00
Mounted panel and receptacle boxes to wood, wired
3 loads + DC motor
Bought ground screws, receptacle plug for motor,
grommets for metal punch-outs in panel, electrical
tape
Corrected red wires going to and from PV and DCto-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
5/19/2006
0.75
Exchanged receptacle plug for motor and grommets
for correct ones (wrong sizes/fit)
5/23/2006
0.10
5/19/2006
1.00
4.50
5/30/2006
1.00
6/4/2006
13.00
Returned items to
Pacific Home and
Garden
diagram (12th
draft)
Home Depot trip
misc. store trips
diagram (13th
draft)
Installation/Wired
cart
diagram (14th
draft)
Prices
6/6/2006
6/6/2006
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
Changed the diagram, wires needed to be
removed/reversed from the pv to dc-to-dc converter
Installed switchboard box, wired everything up
0.50
Changed diagram after installation, removed some
wires from switchboard box, added ground wire from
PV again, changed some wire specs
Added prices, deleted items
1.00
Art 720
EE 464
Found NEC code
for two different
voltages in one
combiner box
Bought 15A plug
adapter for DC tv
Worked on
diagram (15th
draft)
10/10/06
0.50
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
Cleaned up wires
on the cart
Researched and
purchased fuses
Installed fuse for
motor
Ran motor test
Diagram (16th
draft)
Prices
Total
10/17/06
4.00
10/18//06
1.00
4.00
11/1/06
11/7/06
1.00
3.00
11/10/06
11/10/06
0.50
0.50
79.80
With Solar Power and Battery
Changed the 30A Circuit Breaker for the motor to a
30A Fuse
Added items on price list
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
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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
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able to apply what I learned in school and finding out about what is used out in the
real world.