120102b Electricity Flashcards
This term describes a noisy, uncontrollable arc that flares from side to side.
a) arc voltage
b) arc blow
c) inductance
d) resistance
b) arc blow
This term describes the influence exerted by a magnetic field on neighbouring bodies without physical contact.
a) voltage
b) amperage
c) frequency
d) inductance
d) inductance
This is the fundamental unit of electricity that moves through a conductor when current is flowing.
a) resistors
b) electrons
c) conductors
d) rectifiers
b) electrons
Which term describes the NEMA rating of a welding machine?
a) duty cycle
b) direct current
c) arc voltage
d) amperage
a) duty cycle
Electrode positive means:
a) straight polarity
b) reverse polarity.
c) AC transformer.
d) alternating current.
b) reverse polarity.
Electrons have a charge.
a) neutral
b) 12-volt
c) positive
d) negative
d) negative
Which term measures the strength of a current of electricity?
a) amperage
b) voltage
c) electron
d) inductance
a) amperage
What term describes a medium that provides an electrical path for current to flow
through?
a) cycle
b) circuit
c) conductor
d) core
c) conductor
The electron flow theory states that electrons move from.
a) positive to negative
b) negative to positive
b) negative to positive
This term describes a material that can stop current flow through itself.
a) inductor
b) inverter
c) conductor
d) insulator
d) insulator
Which term describes the voltage output of the machine during welding?
a) arc rectification
b) arc blow
c) arc voltage
d) inductance
c) arc voltage
When current flows through a coil wrapped around an iron core, what is created?
a) a magnetic field
b) reverse polarity
c) transformer rectifier
d) duty cycle
a) a magnetic field
This device in a welding machine is designed to have a certain number of turns of wire.
a) circuit
b) core
c) coil
d) cycle
c) coil
The main function of this device is to change AC to DC.
a) resistor
b) rectifier
c) relay
d) reactor
b) rectifier
Electrode negative is:
a) straight polarity.
b) reverse polarity.
c) ac transformer.
d) alternating current.
a) straight polarity.
This current flows in one direction only and has either a positive or negative value.
a) direct current
b) alternating current
c) open circuit voltage
d) arc voltage
a) direct current
Which term describes a piece of equipment used to create electricity of sufficient volume for welding?
a) inductor
b) resistor
c) transformer
d) generator
d) generator
Which is a graphical illustration that plots the relationship between voltage and amperage output of a welding power source?
a) open circuit voltage
b) volt-amp curve
c) electromotive force
d) duty cycle
b) volt-amp curve
When no current is flowing in the circuit, but the machine is turned on, you can measure the:
a) open circuit voltage.
b) constant current.
c) alternating current.
d) volt-amp curve.
a) open circuit voltage.
The speed at which AC changes direction is called the:
a) voltage.
b) amperage.
c) frequency.
d) resistance.
c) frequency.
This term describes the property of an electrical conductor that opposes the flow of current.
a) resistance
b) inductance
c) voltage
d) amperage
a) resistance
In welding, this term describes what is created when there is enough amperage and voltage to overcome the natural resistance to the flow of the electricity.
a) amp
b) volt
c) cycle
d) arc
d) arc
List three (3) advantages of three-phase systems over single-phase systems.
a) constant power
b) smaller equipment
c) more efficient
What phase of power supplies most industrial applications?
a) single-phase power
b) two-phase power
c) three-phase power
d) four-phase phase
c) three-phase power
This welding machine transforms AC to DC.
a) line transformer
b) transformer rectifier
c) DC generator
d) AC transformer
b) transformer rectifier
This term describes one complete revolution of the AC alternator.
a) circuit
b) core
c) coil
d) cycle
d) cycle
What happens when mechanical energy is applied to a conductor and it moves across
the magnetic lines of force in a magnetic field?
a) Magnetism is generated.
b) Electrical current is generated.
c) Single-phase power is generated.
d) Three-phase power is generated.
b) Electrical current is generated.
These machines convert high voltage, low amperage to low voltage, high amperage by the use of a primary and a secondary coil.
a) AC transformer
b) AC generator
c) DC generator
d) AC alternator
a) AC transformer
What does EMF stand for?
a) electron movement force
b) elementary motor force
c) electromotive force
d) electromotive factor
c) electromotive force
Which term describes the typical sound of an AC transformer welding machine?
a) turbine whine
b) high-pitched scream
c) buzz box
d) whisper quiet
c) buzz box
This type of welding machine is capable of changing DC to high frequency AC.
a) AC generator
b) DC rectifier
c) DC generator
d) inverter
d) inverter
What is the function of the secondary winding on a transformer welder?
a) to induce high frequency current
b) to serve as a back-up in case the primary winding fails
c) to step down the voltage
d) to step down the amperage
c) to step down the voltage
One advantage of an AC transformer welder is freedom from:
a) undercut.
b) arc blow.
c) porosity.
d) slag inclusions.
b) arc blow.
What is the purpose of a sil icon-control led rectifier?
a) to change AC to DC
b) to change single-phase to three-phase
c) to increase the welding speed on aluminum
d) to change DC to AC
a) to change AC to DC
What is one advantage of an AC-DC transformer-rectifier welding machine?
a) Arc blow is not a problem.
b) The purchase price is lower than for a transformer.
c) You have a choice of polarity.
d) It does not have to be kept clean and cool.
c) You have a choice of polarity.
In Figure 33 the output voltage or current waveform to a load from a generator that uses slip rings is indicated by which diagram?
a) A
b) B
c) C
a) A
In Figure 33 the output voltage or current waveform to a load from a generator that
uses a commutator is indicated by which diagram?
a) A
b) B
c) C
c) C
A DC motor generator produces what type of welding current?
a) rectified
b) AC
c) DC
d) high frequency
c) DC
How can you change the polarity on an AC alternator welding machine?
a) Switch the cables at the machine.
b) Reverse the direction of the motor.
c) Change the polarity taps on the reactor coils.
d) An AC alternator has no fixed polarity.
d) An AC alternator has no fixed polarity.
What is one advantage of an engine-driven generator welding machine?
a) lower cost
b) portability
c) less noise
d) less maintenance
b) portability
What is one advantage of all transformer welding machines?
a) The maintenance costs are lower
b) There is no choice of polarity.
c) They are not portable.
d) The choice of electrode types is narrow.
a) The maintenance costs are lower
These welding power sources immediately rectify the incoming AC to DC and then transistors create a higher frequency AC. The higher frequency AC is then rectified to extremely smooth DC.
a) transformers
b) generators
c) buzz boxes
d) inverters
d) inverters
How did manufactures reduce the size and weight of transformers and generate significant energy savings over conventional power sources?
a) rectifier technology
b) generator technology
c) inverter technology
d) transformer technology
c) inverter technology
What is an advantage of an inverter welding machine?
a) small and lightweight
b) generally cheaper to buy
c) portability
d) functions well in a dirty environment
a) small and lightweight
What is a disadvantage of an inverter welding machine?
a) poor arc starting characteristics
b) higher input power requirements
c) higher initial cost than transformers or rectifiers
d) cannot be configured for automation
c) higher initial cost than transformers or rectifiers
