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Worksheetspower sources for welding
Total questions: 57
Worksheet time: 29mins
Which statement supports the fact that metals are good conductors?
Their electrons are tightly held by the nucleus
They have many free neutrons
They have many free electrons
They have many free proton
Which statement best describes ionization potential?
The energy required to add an electron to form a negative ion
The energy required to remove an electron to form a positive ion
The energy released when a electron is removed from an atom
The energy required to remove a proton from an atom
Choose the minimum temperatures in the centre of a welding arc column in degrees C
500
1000
5000
50,000
A plasma can best be described as
An ionized gas
An inert gas
A good insulator
A high temperature gas
The major voltage drop(s) in a consumable electrode welding circuit is (are)
The welding cables
The work clamp
The arc plasma
The anode drop, cathode drop and the arc plasma
The statistic characteristics of a welding power source are indicated on a graph which plots?
Voltage verses time
Current verses time
Energy verses time
Voltage verses current
The arc starting characteristics of a CC welding power source are determined by?
The short circuit current
The slope
The input voltage
The open circuit voltage
A voltage sensing wire feed system must be used with a ____ to produce a stable self-regulating welding arc
CC power source
CV power source
CV inverter power source
CV power source with above average droop
The short circuit current in a CV welding power source is determined by
The static and dynamic characteristics
The voltage in the circuit
The shielding gas employed
The arc length
Select the correct statement.
A CC welding power source can be used for the GTAW and PAW processes
A CC welding power source can be used for the SMAW ans SAW processes
A CV welding power source can be used for the GMAW and FCAW processes
All of the above
The advantage of portable alternating welding power sources utilizing a rotating field design is
AC auxiliary power can be produced as well
More reliable, as less current flows through the brushes
Rectifiers can be used to produce DC power
All of the above
The conductor size of the secondary windings of a welding transformer power source is
The same as the primary winding
Smaller than the primary winding
Larger than the primary winding
None of the above
Mechanical reactor control is used on which type of welding power source?
Silicon controlled rectifier
Inverter
Saturable reactor
None of the above
A saturable reactor power source uses ___ to adjust the output
A third winding on the transformer
A transistor
A tapped transformer
A moveable secondary winding
A rectifier consists of components that?
Change DV power to AC power
Slows the dynamic response of the power source
Decreases the frequency of the power source
Changes AC power to DC power
The main components used to rectify are?
Diodes
Transistors
Inductors
Transformers
Components typically used to correct the power factor of a transformer- rectifier welding power source are
Inductors
Resistors
Capacitors
Diodes
SCR controlled welding power sources use _____ to adjust the output.
A tapped transformer
A third winding in the transformer
A gate pulse to indicate conduction by a diode
Transistors
Which was the first welding power source design to incorporate a feedback circuits using magnetic fields?
Inverter
Mechanical reactor
Silicon controlled rectifier
Saturable reactor
An inductor in a welding power source is used to?
Filter DC output and affect the dynamic characteristics
Increase the output voltage
Change AC power to DC power
Change the static characteristics
Which was the first type of welding power source to provide accurate control of the pulsed GMAW process over a wide range of pulse frequencies?
SCR control
Saturable reactors
Inverters
Transistor output
Inverters are used in welding power sources to?
Change AC power to DC power
Filter the output of SCR’s
Increase the output voltage
Change DC power to high frequency AC power
One of the major advantages of inverter welding power sources is?
Low initial cost
Small size and low weight
No need for feedback control
High input voltages
In inverter welding power sources, the inverter is located?
Before the transformer
After the inductor (choke)
Between the output rectifier and the inductor (choke)
Directly after the input
High frequency arc starting circuits use _____ to generate the high frequency
A spark gap
High speed switching transistors
Inverters
Scr’s
Synergic control is typically used for the _____ process
SAW
SMAW
PAW
GMAW
The open circuit voltage of GMAW and SMAW is
The same for both
Different
For SMAW is higher
For GMAW is higher
DC generator is different to alternator because
DC generators have a conductor that moves quickly through a magnetic field
Alternators have a conductor that moves quickly through a magnetic field
DC generators produce a current by the stationary winding
None of the above
Which one of the devices indicated in the following list is used in microprocessor controls?
Resistors
Relays
Transistors
Motors
What is the force or pressure that causes current to flow through an electric circuit?
Resistance
Inductance
Reactance
Electrical potential
Metals are considered good conductors because?
Their electrons are tightly held by the nucleus
They have many free neutrons
They have many free electrons
They have many free protons
Impedance is?
The algebraic sum of resistance, capacitance and inductance
The sum of resistance and inductance
The algebraic sum of capacitance and resistance
Non of the above
What are the possible causes if the arc stops and starts during Welding?
Machine and the duty cycle is too low
An inert gas is too highly concentrated
Machine overload and the duty cycle is too high
Welding cables are too long
Select the correct statement
PAW utilizes a steel electrode
PAW utilizes a tungsten electrode
PAW utilizes a zirconium electrode
None of the above
Factors that facilitate the initiation of an arc starting in a welding machine are
Welder skill and magnetic field
Ty electrode and current
Higher open circuit voltage and induction
The power factor of the welding machine and voltage
In some situations with the SMAW process, such as manual welding of a pipe joint, a flatter slope is used to provide some change in current when arc length changes
True
False
With the GMAW process and a CV power source, the welding current is determined by
The slope of the static characteristic
The setting on the Welding power source
The open circuit voltage
The wire feed speed
With a constant current power source, the steeper the slope
The more the current will vary
The current will not vary
The less control of current
The less the current will vary
What type of power source uses a voltage sensing wire feed system to produce a stable self regulating Welding arc
CC power source
CV power source
CV inverter power source
CV power source with above average droop
In GTAW high frequency systems, incoming AC line voltage is stepped up to several thousand volts by a transformer. Select the correct statement.
High frequency systems are limited to less than 4000 V for safety reasons
The spark gap needs to be at least 75mm (3in) wide for the spark to jump far enough to create the arc
Hi frequency systems output high voltage, but only low current
High frequency systems only work with DC arcs
The severity of an electric shock depends principally on
Magnitude of the current and body size
Magnitude of the current and part of the body through which it passes
Only on the level of humidity in the environment
The amount of current only
Power supplies are selected by process only without consideration of material type and thickness
True
False
The main components used to rectify are
Diodes
Transistors
Inductors
Transformers
Conventional transformer-rectifiers rectify AC current on the secondary side of the transformer at lower voltage and higher current
True
Falae
What two components are used for microprocessor control
Transistors and electronic amplifiers
Saturable reactors and diodes
Feedback circuits and amplifiers
Gates and transistors
The two systems that can be used to adjust the output of a transistor welding power source are
Tapped transformer and SCR
SCR and inverter
Frequency and pulse with modulation
Peak voltage and current feedback
Inverter welding power sources have a very short response time because
The inverter operates at high frequencies
There is no inductor (choke)
The output voltage is high
Feedback is not used
Early DC generators relied on_____ to produce welding power
A chemical reaction
An induced voltage
An alternator
A transformer
A transformer in a welding power source is a device that
Changes the frequency of AC power
Changes AC power to DC power
Filters DC power
Changes the voltage of the AC input power
One of the major advantages of inverter welding power sources is
Low initial cost
Small size and low weight
No need for feedback control
High input voltages
SCR Welding power sources use _____ to adjust the output
A tapped transformer
A third winding in the transformer
A gate pulse to initiate conduction by a diode
Transistors
The capacity to store and recall detailed welding variables in a welding power source is possible due to
SCR controls
Saturable reactors
Feedback circuits
Microprocessor controls
A disadvantage of using DCEN compared to DCEP with the SAW process is?
More distortion
More solidification cracking
Susceptibility to incomplete penetration
More slag inclusions
The conductor size of the secondary windings of a welding transformer welding power source are
The same as the primary winding
Smaller than the primary winding
Larger than the primary windings
None of the above
Which of the following methods is commonly used to control the output of a transformer?
An auxiliary power supply that feeds the secondary as required
A saturable reactor
Resistance placed in parallel with the primary of the transformer
Taps on the secondary of the transformer
When the core of a welding transformer is moved to adjust the output, this type of control is called a:
Moving secondary
Tapped transformer
Moving shunt
Saturable reactor
The formula for the Ohm’s law is?
I=V/R
I=R/V
V=R/I
RV=IR
