TEST #1 Flashcards
1
Q
How does the MLITSD define trouble shooting?
A
Strictly visual, until you pick up a tool
2
Q
What does the MLITSD considerate if you are utilizing a tool such as a multi-meter when work testing for voltage on a circuit?
A
Energized work
3
Q
Have charges been laid against individuals that consider testing and troubleshooting that believed themselves to be exempt from the category of working energized?
A
Yes
4
Q
Does the Ministry of labour have laws regarding working around energized equipment? And what are they referred to as?
A
Yes, and Lock-out, and Tag out.
5
Q
What is the first consideration regarding situational awareness?
A
Safety of personal – is anyone in immediate harm, or am I putting myself in harm’s way.
6
Q
What should be assessed regarding the protection of property?
A
Is there any damage due to the malfunction, do I require to de-energize or make any other equipment at a zero energy state before I proceed.
7
Q
What is required for permission to de-energize circuits?
A
The ability to de-energize circuits must be granted by an owner responsible manager of a business in writing.
8
Q
What pressure might owners exert on electricians?
A
Companies will not want to shut down any aspect of the operations and may pressure you to work energized to minimize operational impacts.
9
Q
What is the duty to report for electricians?
A
If you are aware of a hazard and the owner will not give you permission to de-energize, you have an obligation to report the hazard to the Electrical Safety authority.
10
Q
What should be done if a hazard exists without the owner’s permission?
A
The Electrical Safety authority has the ability to disconnect a power source if a hazard exists.
11
Q
What is visual assessment in situational awareness?
A
Using your sense of vision allows you to detect deformities in electrical components, such as burn marks or tripped breakers.
12
Q
What does the sense of smell indicate in electrical components?
A
Electrical components such as coils give off a unique smell; a blown coil has a distinct odor indicating failure.
13
Q
How can temperature readings be taken safely?
A
Specialized equipment like thermal scanning tools can be used to take temperature readings without physical contact.
14
Q
What can electricians detect through sound?
A
Electricians can detect issues like under-voltage, strain, and mechanical problems by listening to how motors and devices sound.
15
Q
Why is operator or local knowledge important?
A
Asking those who operate the equipment daily can provide insights into issues that may not be apparent otherwise.
16
Q
What is manual actuation in troubleshooting?
A
Devices such as contactors can be manually actuated to help determine if the problem lies in the motor, field wiring, or control wiring.
17
Q
What constitutes a dangerous practice for electricians?
A
Speeding up troubleshooting by methods like dead shorting circuits or ignoring procedures can lead to unsafe conditions.
18
Q
What are safe practices for electricians?
A
Following all policies and procedures, wearing required PPE, and understanding equipment function are essential for safety.
19
Q
What is the human component in electrical work?
A
Electricians should acknowledge that they do not have all the answers and should seek help when uncertain.
20
Q
What are the two main types of circuits in motor control?
A
The two main types of circuits are the control circuit and the branch circuit.
21
Q
In terms of input vs output wiring, which circuit is considered the input?
A
The control circuit is considered the input.
22
Q
In terms of input vs output wiring, which circuit is considered the output?
A
The branch circuit is considered the output.
23
Q
What type of device opens or closes a contact based on parameters like temperature or light levels?
A
Such a device would most likely be found in a control circuit.
24
Q
Are devices that open or close contacts based on parameters considered input or output devices?
A
These devices are considered input devices.
25
What type of device receives a signal and closes contacts to allow current to flow?
This device would best be described as an output device.
26
Are devices that receive a signal and allow current to flow considered input or output devices?
These devices are considered output devices.
27
What type of circuit is a resistive or inductive device that performs a specific task?
This would be a branch circuit.
28
Are resistive or inductive devices that perform tasks considered input or output devices?
These devices are considered output devices.
29
What are the different types of switches?
Single pole, 3-way, 3-position, 4-way, motor starter switch, disconnect switch, and Hand-Off-Automatic switch.
30
Are the switches considered a manual or automatic device?
They can be considered both manual and automatic devices depending on the type.
31
Would the switches be considered an input device or an output device?
They can be considered input devices or output devices depending on their function.
32
In a diagram with both branch circuit and control circuit, where would you most likely find switches?
You would most likely find switches in the control circuit.
33
What are some examples of sensing devices?
Limit, float, pressure, flow, temperature, and timed contacts.
34
List 5 different sensing devices that do not have a standard symbol.
Examples include ultrasonic sensors, photoelectric sensors, inductive sensors, capacitive sensors, and magnetic sensors.
35
What is the purpose of a limit switch?
To detect the presence or position of an object.
36
Are limit switches considered a manual or automatic device?
Limit switches are considered automatic devices.
37
Would limit switches be considered an input device or an output device?
Limit switches are considered input devices.
38
In a diagram with both branch circuit and control circuit, where would you most likely find limit switches?
You would most likely find limit switches in the control circuit.
39
Give an example of a practical application for a limit switch.
Used in elevators to detect the position of the elevator car.
40
What is the purpose of a float switch?
To detect the level of liquid in a tank.
41
Are float switches considered a manual or automatic device?
Float switches are considered automatic devices.
42
Would float switches be considered an input device or an output device?
Float switches are considered input devices.
43
In a diagram with both branch circuit and control circuit, where would you most likely find float switches?
You would most likely find float switches in the control circuit.
44
Give an example of a practical electrical application for a float switch.
Used in sump pumps to control water levels, or suage tanks
45
What is the purpose of a pressure switch?
To monitor and control pressure levels in a system.
46
Are pressure switches considered a manual or automatic device?
Pressure switches are considered automatic devices.
47
Would pressure switches be considered an input device or an output device?
Pressure switches are considered input devices.
48
In a diagram with both branch circuit and control circuit, where would you most likely find pressure switches?
You would most likely find pressure switches in the control circuit.
49
Give an example of a practical application for a pressure switch.
Used in HVAC systems to control fan operation based on pressure.
50
What is the purpose of a flow switch?
To detect the flow of liquid in a system.
51
Are flow switches considered a manual or automatic device?
Flow switches are considered automatic devices.
52
Would flow switches be considered an input device or an output device?
Flow switches are considered input devices.
53
In a diagram with both branch circuit and control circuit, where would you most likely find flow switches?
You would most likely find flow switches in the control circuit.
54
Give an example of a practical application for a flow switch.
Used in water treatment plants to monitor water flow.
55
What are the components of the contractor labeled L1, T1 - L2, T2 – L3, T3 called?
They are called contacts.
## Footnote
Draw the symbols vertically, in a de-energized state, and label correctly using IEC symbols.
56
What do the #1 and #6 represent in L1 and T3?
#1 and #6 represent the specific terminals of the contactor.
## Footnote
We don’t include them in our drawings for simplicity.
57
What does the L and the T stand for?
L stands for line and T stands for terminal.
## Footnote
We attach our feeder or incoming wires to the L terminal.
58
Are L1 and T1 electrically or mechanically connected to the other 2 poles of the contactor?
They are mechanically connected.
59
How are L1 and T1 connected to each other?
L1 and T1 are connected through the contact mechanism of the contactor.
60
How does a contactor work?
A contactor functions as an electrically controlled switch that uses a coil to create a magnetic field, which opens or closes contacts to control power to a load.
61
Do contactors come with different coil voltages?
Yes, contactors can have different coil voltages, which can be either AC or DC.
62
What happens if 240Vac is applied to the coil?
Applying 240Vac to the coil may cause the contactor to operate, but it could also damage the coil if it is not rated for that voltage.
63
What happens if 24Vac is applied to the coil?
Applying 24Vac to the coil will typically allow the contactor to operate correctly, assuming it is rated for that voltage.
64
What is the maximum ampacity for resistive loads through the contactor's contacts?
The maximum ampacity depends on the contactor's specifications and is determined by the resistive load type, such as lighting or heating. 40A
65
Can this contactor control the motor shown on the nameplate?
Whether this contactor can control the motor depends on the motor's specifications and the contactor's ratings.
66
What is the horsepower rating for the motor?
To calculate the horsepower rating, divide the motor's wattage by 746.
## Footnote
Example: If the motor is rated at 1470 Watts, then 1470 / 735.499 = 2 Hp.
67
What is the maximum voltage that can pass through the contacts of the contactor?
The maximum voltage that can pass through the contacts is specified by the contactor's ratings.600v
68
What is the maximum FLA (Full Load Amps) that can pass through the contacts?
The maximum FLA is determined by the contactor's specifications, regardless of the voltage.
69
Can we run different voltages through each pole of our contactor?
Yes, as long as we don’t exceed the voltage rating down any one contact.
70
Can we run different ampacities through each pole of our contactor?
Yes, as long as we don’t exceed the amperage rating down any one contact.
71
Is it permissible not to use all poles of a contactor?
Yes, it is permissible as long as the ratings are not exceeded.
72
What does a set of contacts consist of?
1 common termination point and 1 NC, and 1 NC.
73
How many sets of contacts does an 11 pin control relay have?
3
74
What should the resistance be for a 24 Vac coil in an 8 pin relay?
75 ohms ± 15%
75
What should the resistance be for a 110 Vac coil in an 8 pin relay?
1700 ohms ± 15%
76
Using Ohm's law, how much current does the 24 Vac relay coil use?
0.32 A
77
Using Ohm's law, how much current does the 120 Vac relay coil use?
0.07 A
78
What is the best way to isolate which circuit the issue is in?
Manually actuate the relay or contactor; if the motor runs, the issue is in the control circuit; if it does not, it is likely in the field wiring.
79
Why take a different approach when commissioning a new motor circuit?
A new system has not been proven to be wired correctly, while a failed system has.
80
Is manually actuating the device while the circuit is energized considered energized work if the electrical cover is removed and a Dead Front exists?
No
81
Is manually actuating the device while the circuit is energized considered energized work if energized components are exposed?
Yes, you have passed the limited and restricted approach boundaries.
82
Should you follow company procedures and wear prescribed PPE when troubleshooting a failed circuit system?
Yes, it will eliminate half of the work and may find the problem.
83
How can you verify that all contacts and the relay base are functioning properly at a zero energy state?
Set your meter to continuity, put leads on either end of the NO or NC contacts, manually actuate. If the contacts change state, they are working.
84
How long does it take to verify a relay or contactor prior to installation?
Once you are competent, under 30 seconds.
85
A device that uses inductors to convert AC voltage from one value to another is known as what?
Transformer
## Footnote
Abbreviation: TX
86
What are the names of the inductors or windings given to a transformer (TX)?
Primary and Secondary windings
87
A TX that you apply a lower voltage to the Primary windings, and a higher voltage is expected from the secondary is known as what type?
Step-up transformer
88
A TX that you apply a higher voltage to the Primary windings, and a lower voltage is expected from the secondary is known as what type?
Step-down transformer
89
A TX that is designed to convert field voltage to a lower voltage to facilitate in the functionality of motors or lighting or other electrical devices, but does not feed the device directly. This description describes what type of TX?
Control transformer
90
A TX that is designed to convert a higher voltage to a lower voltage with the intended purpose of supplying a safer lower voltage for the utilization of branch circuits, is known as what type of TX?
distribution transformer
91
A TX that does not transform a voltage difference from the primary to the secondary, meaning it has equal turns ratio (1:1) in both sets of windings, with the sole purpose of reducing electrical noise in the AC waveform such as harmonics is known as what type of TX?
Isolation transformer or a filter
92
Why is it we can only use transformers to change the voltage of an AC source, and not a DC source?
Transformers rely on changing magnetic fields, which only occur in AC.
93
What is the turns ratio for a transformer with 600 VAC on the primary and 24 VAC on the secondary? Show your math.
Turns ratio = Primary Voltage / Secondary Voltage = 600 VAC / 24 VAC = 25
## Footnote
This is a step-down transformer.
94
What is the turns ratio for a transformer with 120 VAC on the primary and 24 VAC on the secondary? Show your math.
Turns ratio = Primary Voltage / Secondary Voltage = 120 VAC / 24 VAC = 5
## Footnote
This is a step-down transformer.
95
What is the power rating we use for larger branch circuit TX’s?
The power rating used for larger branch circuit transformers (TX’s) is typically higher than standard ratings.
## Footnote
Example: Larger branch circuit TX’s may have power ratings of 75 kVA or more.
96
What does CEC Section 26 starting at rule -240 outline?
It outlines the safe installation practices for transformers.
97
What type of transformers does the code book mainly focus on?
Power distribution transformers.
98
Why is there more focus on power distribution transformers?
More power means more potential for problems.
99
What must be followed for control transformers?
Manufacturers markings must be followed and values must not be exceeded.
100
What does the CEC refer to control transformers as?
Instrument voltage transformers.
101
What sections of the CEC should be read pertaining to transformers?
Sections 26-240 to 26-266.
102
Are the primary windings of SIEMANS and HAMMOND designed in the same configuration?
This question requires comparison of the two brands.
103
What TX must connect the secondary windings in the same manner as the primary?
This question requires specification of the transformer type.
104
Can we still get 12 volts on the SIEMANS TX when applying 120 vac?
This question requires an explanation.
105
What is the high voltage winding resistance for the Hammond PH50PG between terminals 1 and 3?
9Ω
106
What is the high voltage winding resistance for the Hammond PH50PG between terminals 2 and 4?
9.8Ω
107
What is the low voltage winding resistance for the Hammond PH50PG between terminals 1 and 3?
.3Ω
108
What is the low voltage winding resistance for the Hammond PH50PG between terminals 2 and 4?
.3Ω
109
What is the high voltage winding resistance for the Siemens MT0050C between terminals H1 and H2?
17.3Ω
110
What is the high voltage winding resistance for the Siemens MT0050C between terminals H3 and H4?
15.7Ω
111
What is the low voltage winding resistance for the Siemens MT0050C between terminals X1 and X2?
.3Ω
112
What is the low voltage winding resistance for the Siemens MT0050C between terminals 3 and 4?
.6Ω
113
What must be removed to measure the resistance of primary and secondary winding?
All wires
114
What law can be used to calculate total winding resistance when jumpers are installed?
Ohm's Law
115
What is needed to solve for total winding resistance (RT) with jumpers?
Knowledge of how the windings are connected (series or parallel)
116
What is the purpose for grounding the X2 Terminal of a control TX?
To ensure safety and proper operation of the control transformer.
117
What is the name used when we do not ground the Neutral?
floating Neutral.
118
Where is the only place in a circuit with a Neutral not grounded we will get a true voltage reading?
secondary side
119
What is a huge disadvantage the Jeff talked about when bonding and not grounding extra-low voltage circuits that supply electrical devices?
Increased risk of electrical shock and malfunction of devices.
120
What is a current limiting device, or commonly referred to as an overcurrent device?
1. automatically opening
2. predetermined overload
3. short circuit conditions
4. fusing of metal
5. electromechanical means
121
List the 2 main types of Overcurrent devices we use.
1. Circuit breakers.
2. Fuses.
122
I would use a ____pole breaker if I wanted single phase 240VAC.
2-pole breaker.
123
I would use a ____pole breaker if I wanted single phase 120VAC.
1-pole breaker.
124
I would use a ____pole breaker if I wanted 208VAC.
2-pole breaker.
125
I would use a ____pole breaker if I wanted three phase 120VAC.
N/A
126
I would use a ____pole breaker if I wanted three phase 208VAC.
3-pole breaker.
127
What are the two main types of fuses used in industry, and more specifically referred to in section 28?
1. timed delay fuses
2. on-time delay fuses
128
Overcurrent device is intended to protect?
the wires (the conductor)
129
What does Table 29 specify?
It is specific to the rating or setting of overcurrent devices that protect motors.
130
What is the allowable increase for a Time Delay Fuse?
For a Time Delay Fuse, I am allowed to go 175%
131
What is the allowable increase for a Non-Time Delay Fuse?
For a Non-Time Delay Fuse, I am allowed to go 300%.
132
What is the allowable increase for a Circuit Breaker?
For a Circuit Breaker, I am allowed to go 250%
133
Why do we need to use large overcurrent devices for motor circuits?
This is necessary to accommodate the starting current of the motor.
134
How do you size a conductor for a single phase AC motor?
We multiply the FLA of the motor by 125%, and that answer is the lowest allowable ampacity of the conductor.
135
What is the example for a motor with an FLA of 10A?
For a motor with an FLA of 10A, we would use a #14 AWG copper conductor at 75 degrees.
136
What is the maximum rating for the breaker in this example?
The breaker is allowed to be 25 amps according to Table 29.
137
How can we allow a larger overcurrent device than the conductor is capable of handling?
Overcurrent protection is intended to protect the wires, but larger devices accommodate motor starting currents.
138
What is one cause of a motor being overworked?
1. Excessive load on the motor
2. dirty blades
3. oil and grease
4. something gets stuck int it
5. thicker liquid
## Footnote
For example, when the motor is required to lift a weight beyond its capacity.
139
What type of overload uses an overload heater as the current sensing device?
A device that holds a spring down to close a set of contacts in the control circuit, allowing current to flow. When not in normal conditions, the overload heater heats up and releases the spring, opening the control circuit contacts.
140
What type of overload relay uses the warping of different metals when heat is applied?
matallic streaps
141
What type of overload relay uses lines of flux generated by current flowing through conductors?
magnetic overload
142
What is the abbreviation that we use for the word overload?
OL
143
Which type of overload has no adjustment?
melting pot
144
Which type of overload does not use heat?
magnetic
145
What are the 2 different types of Magnetic relays?
Electromagnetic relays and Solid-state relays.
146
What are the 3 main factors that allow a Dashpot relay to function?
current flowing through magnetic field,
field causing
147
How many OL contacts are required for a single phase motor?
One OL contact or two depending on location.
148
How many OL contacts are required for a 3 phase motor?
Three OL contacts or one depending on location.
149
What state are OL contacts for the control circuit typically in?
Closed state.
150
What are the additional sets of contacts in OL Relays typically referred to as?
Additional sets of contacts are typically referred to as auxiliary contacts.
151
how do we know what size of overload to use
multiply FLA based on rating of service factor.
152
In your words what is a disconnect?
A disconnect is a device that allows for the safe disconnection of electrical power from a motor.
153
Are we required by the CEC to have a Disconnect for any motor installed?
Yes, the CEC requires a disconnect for any installed motor.
154
List 3 motors in your home that have a disconnect, and in what form is the disconnect?
1. Air conditioner - wall-mounted disconnect switch.
2. Electric water heater - circuit breaker.
3. Garage door opener - pull-out disconnect switch.
155
Is it ok to use a 15A light switch or a 15 A receptacle as a disconnect means for any and all motors?
No, a 15A light switch or receptacle is not suitable for all motors.
156
For motors larger than ¾ HP, what type of disconnect does CEC require us to use?
The CEC requires a suitable disconnect switch or circuit breaker for motors larger than ¾ HP.
