1
Q
What is a Magnet made out of and what does it exert?
A
-Iron Oxide or Special Alloy
-Exerts Invisible Force
2
Q
What type of metals will iron attract?
A
-Iron
-Cobalt
-Nickle
3
Q
What is a Magnetic Flux?
A
-Total Magnetic field passing through a surface.
-It shows how strong the Magnet is
4
Q
What is the Law of Charges? Explain what happens when + - and ++ make contact
A
-Positive and Negative attract
-Positive and Positive, Negative and Negative Repel
5
Q
In the Law of Magnetic Poles, what happens when the same and opposite poles make contact?
A
-N + N Repel
-N + S Attract
6
Q
When it comes to Retaining Magnetism, what happens when youre using soft and hard iron steel and removing it from a coil?
A
-Hard = Retains magnetism (power)
-Soft = Loses magnetism (power)
7
Q
How does Electromagnetism work to power your car, put a picture on a CRT screen turns a Shaft on a motor etc..
A
-Electromagnetism frees electrons to move through conductor
8
Q
What is a current in a conductor?
A
Free Electrons from Electromagnetism
9
Q
Does current flowing through a conductor produce Magnetic field?
A
Yes, around the conductor
10
Q
In Electromagnets, what happens to the Magnetic field if you increase the current flow?
A
Increase magnetic field strength
11
Q
What does turning loops of wire do to the Magnetic field strength?
A
Increase magnetic field strength
12
Q
What is an Ampere-Turn?
A
It’s the Current x Number of wire loops
2amps x 20 turns = 40 ampere-turns
13
Q
Is Magnetic field strength proportional to its ampere-turns? Explain.
A
Yes.
5 amps x 10 coil “turns” = 50
14
Q
What affects Electromagnetism strength?
A
-Size and material of Magnet block
-Number of coil turns
-Amount of Current
15
Q
Does winding the wire into a coil increase the strength of Magnetic Field?
A
Yes
16
Q
What is a Core Material in Electromagnetism?
A
It’s the base (block) that the wires are wound around
17
Q
What is a Core Material?
A
A base (Magnet block) that your wires are wound around
18
Q
What is a Core and are Cores made from a Magnetic material like Iron, greatly increase the field strength.
A
-Core material is the base that the wires wound around - Yes, it greatly increases the field strength
19
Q
What does winding the wire into a coil do to the Magnetic field and how?
A
-Increase the strength.
-The loops allow the magnetic field to focus a lot more in the middle allowing the magnetic field to stack up = stronger magnetic field
20
Q
What is the name for Non Magnetic Cores?
A
Air Cores
21
Q
What does Induced mean in Electrical?
A
-Electromagnetic Induction
-When a magnet and conductor pass each other, the magnetic field it creates forces electrons (electricity) to move through the conductor
22
Q
What is the term for when the a coil produces its own magnetic flux when current is running through it?
A
Magnetomotive Force (mmf)
23
Q
What happens when a Conductor Cuts through a Magnetic Line Flux? What does this mean?
A
-Conductor cutting means a wire passing
Magnetic Line Flux means a Magnetic field
-When a wire passes through a Magnetic field, it creates Voltage
24
Q
What is Voltage?
A
It’s electrical pressure that pushes electricity
25
How is voltage created and how does it interact with electrons(current)
-Voltage is generated by passing a conductor through a magnetic field or vice versa.
-That is called Electromotive Force (EMF)
26
What is Electromotive Force (EMF)?
Voltage.
-It is created by passing a conductor through a magnetic field
-It's the force
27
What is it called when Voltage (EMF) is generated and it moves electrons (current) through a conductor?
Induced Current
28
Explain how Iron, Cobalt and Nickle create their Magnetic field and why other metals are non magnetic
-Iron, Nickle and Cobalt have Magnetic domains
-these Magnetic domains all generate a Magnetic field but pointing in different directions
-when an outside Magnet interacts with another Magnet, their domains all line up to one direction
-this creates Ferromagnetism
-when all domains line up, it creates a stronger magnetic field.
-Iron, Nickle, cobalt have Magnetic domains that easily line up
-Other non metallic metals have a Magnetic field but their domains don't line up so they don't generate a noticable Magnetic field
29
What happens to the polarity of voltage when the conductor is moved the opposite way it was originally moving?
It reverses the polarity of the voltage
30
What happens to the polarity of the voltage when you reverse the polarity of the Magnet (N, S)?
Voltage polarity is reversed
31
What does Magnetic Induction mean and give an example.
Magnetic Induction: Moving a Magnetic field induces electricity in a wire
Example: moving a wire through a electroMagnetic Flux
32
What does a Transformer Circuit look like?
-Square Core (magnetic block)
-Coils wrap around the sides of the square
33
The two coils in a Transformer are called what and which ones are input and output?
-Primary Coil (input)
-Secondary Coil (output)
34
True or False: apply DC is a magnetizibg process? Why
True: DC is keeps the polarities the same therefore keeps the Magnetic field constant
35
What happens to the Magnetizing process when you introduce AC current?
It becomes a De-Magnetizing process because AC current constantly flips the polarities of the Magnet and coils
36
What 2 things can you do to De-Magnetizeban Object?
-Heating it
-Hitting it
37
Does the Magnitude and Direction of the Magnetic Field depend on the SHAPE of the wire?
Yes, the more coils the wire has the more Magnetic field it generates
38
Does the Magnitude of a current also play a role in the magnitude of the Magnetic field?
Yes. The more current, the more Magnetic field it generates. Both Magnetic field from current and Magnet combined = stronger Magnetic force.
39
What is a Solenoid?
A long coil (wrapped) of wire.
40
What happens to the Magnetic field inside the Solenoid (coil of wire) when it's tightly wrapped?
The Magnetic field becomes uniformed
41
What type of Current does a Transformer use and what does it do to Voltage and Current levels?
-AC
-It changes voltage and current levels
42
What is the purpose of using a Transformer?
-Long distance power distribution
-Power Supplies
-Automotive Ignition Systems
43
How does a Transformer work and is it AC or DC?
-AC current runs through the primary coil, coil generates Magnetic field that stimulates the Core to produce its own Magnetic field. Then both Magnetic field stimulate the Secondary Coil to induce current and voltage
44
What are Leads in a Transformer Terminal?
Leads are the wires that come out of the Primary and Secondary Coils
45
What's the difference between High voltage Lead and Low Voltage Leads?
-High Voltage Lead = Primary Coil
-Low Voltage Lead = Secondary Coils
46
What are the Functions of High and Low Voltage Leads?
-High Voltage Lead = Handles higher pressure of Voltage
-Lower Voltage Lead = Handles lower pressure of Voltage
47
In a Low Voltage Lead, the Voltage is much lower. What is a lot higher here compared to High Voltage?
Amps
48
What are the Letter Symbols for High and Low Voltage Leads?
H1, H2 = High Voltage Lead
X1, X2, = Low Voltage Lead
49
How do you know which one the Primary AND Secondary Coils are in a Transformer and why?
-Primary Coils: have more coils wrapping around tightly
-Secondary Coils: Less coils wrapping around and wrappings are more seperated.
Why:The more coils that are tightly wrapped the more it increases the Magnetic field which causes a stronger Magnetic field
50
What are the Primary and Secondary Coils connected to?
Primary Coil. : connected to Incoming power supply (Inlet)
Secondary Coil: connected to Driven Load (Outlet)
51
Each set of windings on Primary and Secondary form loops wrapped around the core. What are EACH of the loops called?
A Turn.
52
How do you determine the ratio of voltage on Primary and Secondary Coils?
-The voltage ratio depends on how many TURNS the coils have for both Primary and Secondary Coils
- Volts-Per-Turn
53
Is the volts-per-turn ratio the same on both Primary and secondary windings?
Yes
54
How do you know how many volts there is in a primary and Secondary Coil?
Each turn = 1 volts.
200 turns =200 volts etc..
55
True or False: Push Buttons are the most used symbols in Control Schematics?
True
56
Can Push Buttons be shown as Normally Open or Normally Closed and give an example?
-Yes
-Emergency Stops
57
Are most Push Buttons Momentary Contact Devices and what does that mean?
Yes. It means that the are spring loaded to go back to open circuit position
58
Is this Normally Open or Closed?
Normally Open
59
Is this Normally Open or Closed?
Normally Closed
60
What symbol is this?
Push-Pull Button
61
What do some Push-Pull Button's usually containt?
Normally open or Normally closed contacts
62
Do Push-Pull Buttons come in a variety of contact combinations?
Yes
63
What does a Lighted Push Button usually equipped with to reduce voltage?
Transformer
64
What do these basic symbols mean? "NO" and "NC"
NO= Normally Open
NC = Normally Closed
65
What do these basic symbols mean? "NOHC" and "NCHO"
NOHC = Normally Open Held Closed (just holding down a button to close circuit)
NCHO = Normally Closed Held Open (just holding down a button to cut circuit)
66
SENSING DEVICES
What do Sensing Devices determine?
Occurring Conditions (what is currently happening)
67
What is a Limit Switch and what does it do?
-Position Sensors
-They detect when something reaches a certain point
68
How does a Limit Switch work?
When something touches it, it either turns on or off
69
What is a Limit Switch's purpose?
To start, stop, or change the motion of a machine at a specific position
Ex. a motion are moves something, when it touches the limit switch, it stops.
70
How do you identify the symbol of a limit switch?
It has a wedge triangle on a straight line
71
What is this symbol?
Normally Closed Limit Switch
72
What is this symbol?
Normally Closed Held Open Limit Switch
73
What is this symbol?
Normally Open Held Closed Limit Switch
74
For Contact Symbols, what type of contact is this?
Normally Open Contacts
75
For Contact Symbols, what type of contact is this?
Normally Open Contacts
76
For Contact Symbols, what type of contact is this?
Normally Closed Contacts
77
For Contact Symbols, what type of contact is this?
Normally Closed Contacts
78
What is this symbol?
Normally Open Push Button
79
What is this symbol?
Normally Closed Push Button
80
What is this symbol and give an example?
Normally Closed and Normally Open Push Button
Ex. -Closes one Circuit and Opens Another
-STOP button (cuts the circuit but turns on a light)
81
What is this symbol and give an example?
ON/OFF
-Single Pole Selector
-Toggle Switch
Ex: Door Bell
-Press Button = Door Bell Rings
-Release Button = No Ring
82
What is this symbol and give an example?
2 Positions
-Single Pole Selector
-Toggle Switch
Ex: Light switch
-Switch Up = Lights on
-Switch Down = Lights off
83
What is this symbol and give an example?
3 Positions
-Single Pole Selector
-Toggle Switch
Ex:
-Switch up = Machine moves forward
-Middle = Machine is off
-Switch Down = Machine moves reverse
84
What is this symbol and give an example?
Time Delay
Close Switch
Ex: Fan Switch
-Press Button = It turns on after 5sec
85
What is this symbol and give an example?
Normally Open Foot Switch (Spring Return)
Ex: Sewing Machine Pedal
86
What is this symbol and give an example?
-Normally Closed Relay
-Contactor Contact
Ex: Safety Shut Down Circuit
87
What is this symbol and give an example?
-Normally Open Relay
-Contactor Contact
Ex: Motor Start Contact
88
What is this symbol and give an example?
Control Relay Coil
Ex: Relay Activating a Control Circuit
89
What is this symbol and give an example?
Pilot Light
Ex: Pilot Light Showing OFF
90
What is this symbol and give an example?
Pilot Light
:Pilot Light ON
91
What is this symbol and give an example?
Fuse:
Ex: Blows to protect circuit overload
92
What is this symbol and give an example?
Battery
Ex: Car Battery
93
What is this symbol and give an example?
Normally Open Limit Switch
Ex: Conveyor Stops when box hits switch
94
What is this symbol and give an example?
Normally Closed Limit Switch
Ex: Emergency Stop on Machine Guard
95
What is this symbol and give an example?
Fixed Resistor
Ex: Limiting current to LED
96
What is this symbol and give an example?
Normally Closed Foot Switch
Ex: Press to Stop Machine
97
What is this symbol and give an example?
Transformer
Ex: Stepping 120V down to 24V
98
What is this symbol and give an example?
Normally Open Fluid Level Switch
Ex: Turns Pump ON when tank is low
99
What is this symbol and give an example?
Full Wave Bridge Rectifier
Ex: Converting AC to DC in a power supply
100
What is this symbol and give an example?
Variable Resistor
Ex: Volume knob on a radio
101
What is this symbol and give an example?
Diode
Ex: Allows current one way in a circuit
102
What is this symbol and give an example?
Open on Rising Temp switch
Ex: Heater turns OFF when too hot
103
What is this symbol and give an example?
Close on rising temperature switch
Ex: Fan turns ON when hot
104
What is this symbol and give an example?
Open on rising pressure switch
Ex: Compressor shuts OFF at high pressure
105
What is this symbol and give an example?
Close on rising pressure switch
Ex: Pump turns ON when pressure increases
106
What is this symbol and give an example?
Circuit breaker
Ex: Trips when circuit overloads
107
What is this symbol and give an example?
Solenoid
Ex: Door lock actuator
108
What is this symbol and give an example?
Inductor reactor coil
Ex: Motor starter coil reducing surge
109
What is this symbol and give an example?
Capacitor
Ex: Helps start an electric motor
110
Unit 6 Relays & Contactors
111
What is the difference between a Relay Device vs a Limit Switch?
Relay Device = Push Button
Limit Switch = a Sensor/Button that an object interacts with to engage a cycle in a machine
112
Is a Relay operated Electrically or Manually?
Electrically
113
Can Relay devices be controlled remotely?
Yes
114
Do Relays contain an Auxiliary Contacts?
Yes
115
What is an Auxiliary Contact?
-A secondary contact for a Relay
-Ex. When you power on a machine, the light turns on
116
What are Auxiliary Contacts intended to be used for?
Small Applications
117
Can Auxiliary Contacts control Large amounts of current?
No
118
What is the Current ratings for most relays?
1-10 amperes
119
What is a Magnetic Relay similiar too?
a Solenoid
120
What is the difference with Clapper Type contact?
-Contains one moveable contact (Armature)
-2 stationary contacts
-Single Pole (Double Throw)
121
MECHANICALLY HELD CONTACTORS AND RELAY
Employs two electromagnets to operate?
-Latch Coil
-Unlatch Coil
122
What symbol is this?
SPDT
Single-Pole, Double Throw
123
Unit #7 Basice Control Circuits
Double Pole, Single Throw
124
Double Pole - Double Throw
125
How many wire types can Control Circuits be divided into?
-Two-Wire
-Three-Wire
126
What is a Two Wire Circuit Control?
2 wires that complete a pathway for electricity
127
What are the two types of wires that make up a Two-Wire Control Circuit?
-Hot wire
-Return (Neutral) wire
128
TWO WIRE CIRCUIT CONTROLS
Can a Two Wire Circuit Control be a simple switch that makes or breaks a motor connection?
Yes
129
How can a Two Wire Circuit Controls control a three-phase motor?
By controlling power applied to the motor starter
130
What are two device examples of where you can find a two wire control?
-Thermostat
-Float Switch
-Pressure Switch
131
Can a Two Wire Circuit contain any number of external sensing devices? Give examples
-A complete circuit will have branching out circuits to other devices
-Like a Series Circuit
-If main line is open, everything turns off
132
What does a Three-Wire-Circuit do?
Adds a 3rd wire to a 2 wire circuit
133
What's the benefit of adding a 3rd wire into a 2 wire circuit?
Allows machines/devices to continue working when stopping one
134
What is this Symbol and what does it do?
-Overload (heater element)
-Acts like a fuse to protect motor
135
UNIT#8 MOTOR CONTROLS
136
What does Motor Control do on motors that drive various pieces of equipment?
Motors:
-Starts
-Stops
-Reverse
137
Can a Motor Control be as simple as an On/Off switch for a Motor?
Yes
138
Can a Motor Control be as Complex as to control several motors?
Yes
139
What is a Manual Starter Single Phase example?
Circuit Breaker
140
A Single Circuit can start a ___ Phase Motor?
Single Phase Motor
Ex: Small motor,pumps, fans etc..
-Turn ON/OFF
141
How many Phases does a Three-Phase Starter usually start?
-Three Phase Motors
-Larger Motors, Conveyors, Compressors
-Turn ON/OFF a machine and it sometimes have overload protection
142
What does this symbol mean?
-Normally Open Circuit
-"M" This circuit means it belongs to Motor
143
What does the circle with a vertical line in this symbol mean?
0 with vertical line means = Phase
0|+ 3 = 3 Phase motor
144
What are some Motor Connections you should consider when connecting a motor?
-Horsepower
-Full Load Current Rating
-Voltage
-Marked Temperature Rise
-Service Factor
-National Electrical Manufacturers Association (NEMA)
145
What are the 3 types of Control Systems?
-Manual
-Semiautomatic
-Automatic
146
Give an example of a Manual control
Operator must go to the controller and operate.
Example: Hold a foot pedal to jog
147
Give an example of Semiautomatic control?
Operator pushes a button, limit switch etc.. magnetic contactor makes contact and or starter
Example: You push a button, gripper arm robot moves for you
148
Give an example for Automatic
Same thing as a Semiautomatic but without the operator
Example: Limit switch senses a box, an arm pushes box out to the Spur Conveyor
149
UNIT #9 JOGGING & INCHING
150
Jogging starts a motor with ______ of power at _____Voltage?
Short Jabs, Full Voltage
151
Inching starts a motor with _____of power at ______Voltage?
Short Jabs, Reduced Voltage
152
Where does Jogging Circuits prevent holding contact from sealing circuit around?
Start Push Button
153
Do both Jogging and Inching prevent holding contacts from sealing the circuit?
Yes, both prevent contact from sealing a circuit
154
Do you require a special motor starter rated for jogging duty?
Yes, an inching/jogging motor starter so the circuit does not maintain closed.
155
What type of push button does a Jogging control need?
Double Acting
156
When using a Push Button and a persons finger accidently slips off, could the spring reestablish connection (reconnect itself) with normally closed contacts? Explain what happen
Yes. The motor will continue running. This could be extremely hazardous
157
What happens when you add a control relay to a jog circuit?
It should delay/control the circuit
Level 3
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