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WorksheetsREVISION ON ELECTROMAGNETS
Total questions: 67
Worksheet time: 1hrs 16mins
A Relay is a __________ switch
Magnetic
Electrical
Pneumatic
Electro magnetic
In a Normally Closed (NC) relay, Contact is _______when the relay is not energyzed.
Open
Closed
What does a fuse serve for?
Fuses serve to protect them against overcurrents and short-circuits.
Fuses serve to protect them against an open and short-circuits.
Fuses serve to protect them against an open and low-frequency.
What are the main parts of a relay ?
an electromagnet, a spring and an armature
an electromagnet, a relay and an armature
an electromagnet, a spring and an ammeter
When a current starts flowing in the electromagnet winding, the armature _______.
closes
moves
bring
When a current starts flowing in the electromagnet winding, the spring ________ the contacts.
moves
changes
closes
Across the line starting Is the simplest and cost-effective method of starting the motor. Which type of starting the moter are used with larger motors or where remote control is desired?
Manual starters
Magnetic starters
Auxilliary starters
Pushbutton starters
Across the line starting Is the simplest and cost-effective method of starting the motor. Which type of starting the motor are often used for smaller motors?
Manual starters
Magnetic starters
Auxilliary starters
Pushbutton starters
It is an electromagnetic switch that is used for connecting and disconnecting electric current. It has a similar function as a relay except that the magnetic contactor has higher current ratings and can be controlled remotely
Thermal Overload Relay
Miniature Circuit Breaker (MCB)
Contactor
Relay Coil
Identify the symbol shown by the figure?
Limit Switch
Bi-metallic Thermal Overload Relay
Push Buttons
Contactors
A current-carrying coil in a magnetic field experiences a turning effect.
How can the turning effect be increased?
increase the number of turns on the coil
reduce the size of the current
reverse the direction of the magnetic field
use thinner wire for the coil
Relay is an electromagnetically operated switch. It has coil and contacts.
True
False
The following are applications of using electrical relay
Industrial Automation
Lighting Systems
Elevators Control Systems
Electrical Heaters
All of the Above
Please provide reasons why we need proper documentation.
A) Standardize business practices.
B) Reduce time efficiency in locating document
C)Simplifies processes and makes information less accessible.
All the above
7. Type of document we need to be kept
A : Invoices
B : Cheque butts
C : Bank statement
D :Payroll record
E : All the above
What is a Gantt chart?
A timeline that is used as a project management tool to illustrate how the project will run
A map of how you will complete a project
A table that shows what each task looks like
A project management tool
What do we mean by task dependencies?
Each task is on its own
An important stage within the project
Tasks are influenced by another task
What is contingency time?
Additional time allocated for unexpected events
2 or more tasks can be carried out at the same time
When a task is influenced by another task
What is an advantage of a Gantt Chart
Task time is estimated so the plan may be unrealistic
Tasks are shown against a time scale
It is used to manage a project
the figure shown is for
transformer
Resistor
Capacitor
Resistor
the picture is for
full wave rectifier bridge
half wave rectifier
switching circuit
What is the function of a power supply?
converts AC to DC
converts DC to AC
convert current to voltage
convert water to light
In the power supply, which components do the conversion of AC to DC?
Filter
Transformer
Rectifier
Voltage Regulator
What is the common component of a filter circuit?
diode and resistor
IC regulator and capacitor
resistor and capacitor
The electrical circuit used to get smooth dc output from a rectifier circuit is called
Oscillator
Filter
Amplifier
Logic Gate
What is a resistor?
An electrical component that produces light
An electrical component that helps to limit current, divide voltage and produce heat
An electrical component that produces sound
An electrical component that generates power supply
what is a diodes function
allows current to flow in one direction
allows current to flow in two directions
is a resistor
The number of diodes used to build a bridge rectifier
1
2
3
4
What will happen, if we connect capacitor to DC Supply.
It allows DC
It blocks DC
t rectifies
None of these
Hint: Diode is unidirectional and uncontrolled device. In rectifier circuit, diode use as a switch to convert ac to dc for rectification purpose.
A power panel is also called,
Distribution Panel
Raceway
Main Panel
House Panel
a current that flows in one direction only
Series Current
Alternating Current
Parallel Current
Direct Current
What is the name of the device in the figure shown ?
Overload relay
Float switch
push button
Limit Switch
What is the name of the device in the figure shown ?
Overload relay
Float switch
push button
Limit Switch
What is the name of the device in the figure shown ?
Overload relay
Indicator lamps
push button
Limit Switch
What is the name of the device in the figure shown ?
relay
Float switch
push button
Limit Switch
Which type of cable would be the best for mechanical protection outdoors
Mineral Insulated
FP 200
HOFR flex
SWA
Where would you most likely use metal trunking?
For data cables in a commercial setting
Industrial installation with singles wiring
Embedded in a wall behind plasterboard
Instead of skirting board in a house
Purchase order is a ______.
Request to the supplier to supply materials
Request to the supplier to verify the stock
Acknowledgement of goods
Sales invoice
What set of systematic plans and actions prevents any work related accidents and illnesses?
Operational Safety and Health Procedures
Structural Safety and Health Procedures
Occupational Safety and Health Procedures
Organizational Safety and Health Procedures
What do you call a potential source of any harm or adverse effect to anyone?
danger
hazard
risk
threat
Worn electrical cords and plugs, and exposed wiring
Chemical Hazard
Mechanical Hazard
Electrical Hazard
Physical Hazard
Leaving tools on top of ladders
Chemical Hazard
Mechanical Hazard
Electrical Hazard
Physical Hazard
Workplace safety is the responsibility of __________________.
Employees
Employers
Everyone
Supervisors
A _________________ is a raised platform used to hold workers and materials during construction of a building.
ladder
stairwell
scaffold
crane
Protection from accident, damages, risk hazard or damage is called as____
Safety
Precaution
Prevention
Anticipation
How can one prevent slips, trips and falls?
Cleaning up spills immediately and keeping pathways clear and clean.
By developing a emergency evacuation plan.
Making sure that the facilities have a smoke detector and fire alarm.
None of the above.
Which of the following should you ALWAYS do when lifting?
Lift with your legs
Twist when lifting
Try to lift unilaterally (with only one side of the body)
Ensure that your back is straight
When using a fire extinguisher, you should follow the PASS acronym. PASS stands for...
Pull (the pin), aim, sweep, squeeze
Pull (the pin), aim, squeeze, sweep
Pin (the pull) after shooting solid
Pull, aim, squeeze, shoot
What type of installation would metal conduit normally be used for?
Industrial
Domestic
Special locations
All of above
Which one is a fuse box?
Which of the following devices measures current in an electric circuit?
an ammeter
an ohmmeter
a voltage meter
a resistor
Name the electrical tool/instrument
Multi-tester
Ammeter
Clamp ammeter
Voltmeter
What comes under manual handling?
Pushing, pulling, lifting
Pushing, pulling
Pulling
Pulling, photography
What is the 1st step when you perform manual handling?
Lift the weight
Clear the path from obstacles
Assess the weight
Call for help
What is a hazard?
the potential to cause harm
someone slipping
someone being in the way
someone not adhering to health and safety
In a de-energized normally open contactor:
The contacts are touching
The contacts do what they feel like
The contacts are NOT touching
These are devices used to break and connect the connection in an electric circuit.
Relays
Fuses
Switches
Receptacles
These are mechanically operated devices for a repetitive start on and break up of an electric power track under regular condition.
Relays
Contactors
Fuses
Receptacles
On pressing the green actuator the normally open contact will _______?
Close
Open
Jump
Shake
On pressing the red actuator the normally closed contact will _______?
Close
Open
start
stop
Generally contactors have three main contacts plus _____ auxiliary contact(s)
1
2
3
4
The simplest form of motor starter for the induction motor is the ________?
star-delta starter
Direct On Line starter
offline starter
online starter
Overload relays are designed to operate between 110% and________ of the set value
120%
140%
130%
180%
