Theory Mod 8-11 Flashcards
1
Q
In lead acid batteries what is the cathode anode and electrolyte comprised of?
A
Anode plate is made of lead
Cathode plate is made of lead dioxide
Electrolyte is sulfuric acid and water
2
Q
Are lithium ion batteries rechargeable?
A
Yes
3
Q
What are advantages of lithium ion batteries?
A
High energy density
Lightweight
Long life span
Good long-term performance
Temperature tolerant
Low self-discharge
Fast charge time
Customizable technology
4
Q
A fuel cell is an example of EMF production using what?
A
Chemicals
5
Q
One cubic centimeter of quartz with two kilonewtons of correctly applied force can produce a voltage of…?
A
12,500 volts
6
Q
What kind of material does a piezoelectric effect occur in?
A
Non-conductive
7
Q
What type of device is a Van de graaff generator?
A
Electrostatic
8
Q
What is a Seebeck effect?
A
When the magnitude and direction of the current is a function of the temperature difference between the junctions of a thermocouple
9
Q
The voltage generated by a thermocouple is approximately_______ to the temperature difference between the two cold junctions.
A
Proportional
10
Q
What is piezoelectricity?
A
The voltage generated by the pressure applied to certain materials
11
Q
What is the best known piezoelectric material?
A
Quartz
12
Q
A solar cell generates electricity using light what is this effect called?
A
Photoelectric effect
13
Q
When a conductor is moved through a magnetic field or when the field is moved across a conductor the EMF developed is called……?
A
Electromagnetic induction
14
Q
What is Faraday’s law of induction?
A
Faraday’s law of induction states that the magnitude of the voltage induced in a conductor is directly proportional to the rate at which the conductor cuts lines of force
15
Q
What is the approximate ratio of time and lines of force cut?
A
100 million lines of force cut per one second is equivalent to 1 volt being induced across a conductor
16
Q
What are three factors affecting the value of induced voltage
A
Flux density or strength of the field
Length of the conductor within the magnetic field
The rate at which lines of force are cut by the conductor
17
Q
What is the charge of a balanced atom?
A
Net charge zero
18
Q
What is the charge of an atom with a deficiency of electrons?
A
Net positive charge
19
Q
What is the charge of an atom with excess of electrons?
A
Net negative charge
20
Q
What is an example where a Van de graaff generator is used?
A
Particle accelerators
21
Q
What is tribocharging?
A
The separation of electric charges that occur when two materials are brought together into contact and separated
Much like rubbing your feet on a carpet
22
Q
A basic battery cell May consist of an electrolyte and two:
A
Dissimilar metal plates
23
Q
Can a primary or secondary battery cell be recharged?
A
Secondary
24
Q
What is the formula for calculating the voltage inside of a battery circuit?
A
V = E - IR
25
What are the three main types of lead acid batteries?
Flooded cell
Gelled electrolyte cell
Absorptive glass mat or AGM
26
How many volts per cell can a lead acid battery produce?
2.1
27
For a lead acid battery how many volts per cell should it never drop below?
1.75
28
Are the gases released during recharge of a lead acid battery dangerous?
Highly dangerous and can cause explosions
29
What does vrla stand for?
Valve regulated lead acid
30
What is the number of volts per cell for a gelled electrolyte battery
1.2
31
Are gelled electrolyte batteries maintenance free?
Yes
32
What are the cathode and anode and electrolyte made out of in nickel cadmium batteries?
Cathode or positive plate is made out of nickel hydroxide
Electrolyte is made out of potassium hydroxide
Anode or negative plate is made out of cadmium hydroxide
33
What is the open circuit voltage of nickel cadmium batteries?
1.2
34
What are some advantages of nickel cadmium batteries?
High energy to weight ratio
Low internal resistance
Fast recharge
Long storage life
Reliable operation in high or low temperatures not susceptible to freezing
Long life cycle
Capable of complete discharge and recharge with no damage
Low maintenance
The main downside however is that nickel cadmium batteries are carcinogenic and extremely toxic to aquatic environment
35
What is the voltage produced in lithium batteries?
1.5 to 3 volts
36
How much can a lithium battery store in terms of Watts?
150 watt hours of electricity in 1 kg of battery
37
What does the positive temperature coefficient or PTC switch do?
Stops current flow keeping the battery from overheating
38
Does a lithium battery include an alkaline cell?
Yes
39
How many volts can a typical alkaline cell produce?
1.5
40
What are some advantages of lithium batteries?
Lightweight
Highly reactive so more energy
Hold their charge
Can go through hundreds of charge and discharge cycles
41
If a completely discharged cell is connected in parallel with one that is fully charged what could happen?
Kaboom
42
When two batteries are connected in series is it the voltage or the capacity that remains the same between the two of them?
The capacity remains the same the voltage increases
43
With two batteries connected in a parallel configuration is it the voltage or the capacity that remains the same?
The voltage remains the same the capacity increases
44
In a series parallel configuration what remains the same as the voltage or the capacity?
Trick question nothing remains the same because this configuration allows for higher voltage and capacity
45
Is a modular configuration maintenance and management free?
No. it does however simplify maintenance and management. it is critical to the longevity and optimal performance
46
What CEC code section would you be able to find the installation of equipment in battery rooms?
Section 64-800
47
How do you calculate an ampere hour rating?
Amps multiplied by hours
Current multiplied by time in hours
48
What is the minimum given time that you can calculate an ampere hour for if not provided a Time?
At least 0.5 hours or 30 minutes
49
Terminal voltage must never be lower than______ percent of the rated voltage of a battery.
91%
50
What is cranking amps or CA?
Cranking amps indicates the current that can be drawn from a fully charged battery for 30 seconds at 0° c without the cell voltage falling below 1.2 volts per cell
51
What is cold cranking amps?
The rating that indicates the current flow that can be drawn from a fully charged battery for 30 seconds at a temperature of minus 17.8° c or 0° f without cell voltage falling below 1.2 volts per cell
52
How is reserve capacity performance rating measured?
Minutes
53
What does reserve capacity performance rating state?
Maintaining a current of 25 amps at 25° c before the voltage drops to 1.75 volts per cell
54
Solar modules consist of how many photovoltaic cells?
36
55
What type of semiconductor material produces the most efficient photovoltaic cells?
Gallium arsenide
56
What is the particle of light that gives off energy called?
Photon
57
Is the polarity of the top of a photovoltaic cell positive or negative?
Negative
58
Photovoltaic cells use what type of energy from the Sun to produce electrical energy inside the cell?
Electromagnetic radiation in the form of photons
59
What component of a photovoltaic system converts direct current voltage into alternating current voltage?
An inverter
60
By how much can a single axis solar tracking system improve the total amount of power produce in a photovoltaic system?
20%
61
The conversion of sunlight into electrical energy is a process called:
Photovoltaic action
62
what is the default or standard material used as a semiconductor for photovoltaic cells?
Silicon
63
Is voltage directly or inversely proportional to the temperature of silicon?
Inversely
64
Is current directly or inversely proportional to the photovoltaic cell surface area and level of light intensity?
Directly
65
What is the most common output of silicon cells
0.5Vdc
66
When photovoltaic cells are connected in series what will happen to the voltage?
Increase, however current output will remain the same
67
When photovoltaic cells are connected in parallel what will happen to the voltage?
Voltage will remain the same however current output will increase
68
What does a typical module of photovoltaic cells connected in series consist of in terms of quantity of photovoltaic cells and voltage produced?
36 photovoltaic cells can produce anywhere from 12 to 18 volts for direct current
69
In the surface area of a cell what would happen to current and Power by increasing the cell size?
Current and power also increase
70
What does the intensity of light striking the cell do to the current and Power?
Hire some light levels are equivalent to higher generated values of current and Power
71
What is the ideal angle of light striking the cell?
90°
72
What are three main components in a photovoltaic system?
Photovoltaic panels
Inverters
Electronic components
73
What percentage can solar trackers increase the total of power produced in Watts for a single axis system?
20%
74
Solar trackers can increase the total amount of power to produced in Watts by what percent for dual axis systems?
30%
75
How are batteries used in photovoltaic systems?
Both standalone and hybrid photovoltaic systems May utilize storage batteries to store and or supply energy to critical loads.
76
What are a few hazards when working with photovoltaic systems?
Hazards include:
Fall from Heights
Working on ladders
Working outdoors
Contact with energized electrical components
Heavy lifting
Slips trips and falls
77
The lines of force set up around a magnet is referred to as:
Flux
78
Current flow in a conductor produces:
A magnetic field
79
What determines the polarity of an induced voltage in a current when it is moved through a magnetic field?
Faraday's law
80
What will happen to the voltage if the length of a conductor moving through a magnetic field is increased?
Voltage will increase
81
What occurs when a change of current in one circuit induces a voltage in another circuit?
Mutual induction
82
Slip rings on a simple generator provide a means of:
Connecting the load conductors to the generator
83
What are some examples of ferromagnetic materials
Ferromagnetic materials are metals that can be easily magnetized
Iron nickel Cobalt and manganese
84
What are some examples of paramagnetic materials?
Metals that can be magnetized but not as easily as ferromagnetic materials:
Platinum titanium chromium
85
What are some examples of diamagnetic materials?
Diamagnetic materials are metals or nonmetals that cannot be magnetized
Copper brass and antimony
86
What are permanent magnets found in a natural state in a mineral called?
Magnetite
87
If there is a repelling action between magnetic lines of force why is this?
Like poles repel North and North or South and South
88
Lines of force around a magnet are collectively known as the....
Magnetic flux or simply flux
89
What is flux density?
Flux density relates to the concentration of lines of force around or within a magnet
90
What is permeability?
It is a material property that determines the ease with which magnetic flux magnetizes that material
91
In the same way that materials in an electric circuit resist electric current materials offer_____ to magnetic flux
Reluctance
92
Any material brought near a magnet will behave like a magnet this is the act of:
Residual magnetism
93
What are three factors affecting electromagnet strength?
The amount of current in the coil
The number of turns on the coil
The type of core that is part of the magnetic circuit
94
The strength of the magnet is_______ proportional to the number of turns
Directly
95
When a conductive material such as the iron core of an electromagnet device is subject to changing magnetic fields. As a result currents flow within the core, what is this called?
Eddy currents
96
When heat is produced and subsequent energy is lost due to circulating currents what is it called?
Eddie current loss
97
If a device is operated from an AC supply and magnetic domains keep changing causing friction which in turn produces heat what is it known as?
Hysteresis loss
98
As current is increased the magnetism will ________
Increase
99
If the current in a conductor is switched off what happens to the magnetic field around the conductor
Collapses
100
A generator is a device that converts_____ energy into _____ energy.
Mechanical energy into electric energy
101
When the wire loop is rotated through the magnetic lines of force in the magnetic field an EMF or voltage is induced in the conductor this is known as....
Faraday's law of induction
102
What part of a generator comprises the magnetic circuit?
The field yoke or frame
Pole cores also known as a stator
The armature also known as the rotor
An air gap
103
What are the electrical components of a generator?
The field coils or windings
The armature coils or windings
The brushes
104
For Fleming's left hand rule for generators, what does your first finger second figure and thumb show?
Thumb points in the direction of the movement of the conductor
First finger points in the direction of the magnetic field from north to south
Second finger points in the direction of current flow from negative to positive
105
For the production of voltage across magnetic lines of force, what direction would produce:
Total magnetic force
Fewer magnetic force
Zero magnetic force
Total magnetic force is measured directly across
Fewer magnetic force is measured diagonally
Zero magnetic force is measured straight down
This is all looking at a magnet from top to bottom standing vertically
106
When looking at the positions on a generated waveform
Point a is far right
Point b is top
Point c is far left
Point D is bottom
On a generated waveform what is the voltage?
Point a is zero
Point b is maximum
Point c is 0
Point D is minimum
107
What are factors affecting the value of generated voltage?
The speed at which a conductor is passed through the magnetic field
The flux of the magnetic field
The length of conductor
108
What is the purpose of slip rings?
Slip rings supply an alternating current to the external circuit
109
In an AC circuit with an armature loop at position 0°, how much voltage is being produced?
0
110
In an ac voltage with the armature loop position from 0° to 90°, what is the voltage produced?
Max
111
In an AC circuit with the armature loop position from 90° to 180°, what is the voltage produced?
0
112
With the armature position from 180° to 270° and an AC circuit what is the voltage produced?
Minimum
113
In an AC circuit with the armature loop from position 270° to position 360°, what is the voltage produced?
Zero
114
A split ring is also referred to as a:
Commutator
115
What is the difference with split rings between an alternating current and a direct current generator?
Alternating current uses two split rings, direct current generator uses one
116
Armature loop at position 0° on a direct current circuit will produce how many volts?
0
117
Armature loop position from 0° to 90°, will result in how much voltage on a direct current?
Max
118
Armature loop position from 90° to 180°, will result in how many volts induced in a direct current?
0
119
How much are loop position from 180° to 270°, will result in what voltage across a DC circuit?
Max
120
