Lesson 6: Generators, Motors, and Transformers
_____-_______ transformer confines more magnetic field lines in primary winding because secondary is wrapped around it
"Shell-type" transformer confines more magnetic field lines in primary winding because secondary is wrapped around it
___________ is another device that uses interacting magnetic fields produced by changing electric current. It does not convert one form of energy to another but rather transforms electric potential and current into higher or lower intensity.
"transformer" is another device that uses interacting magnetic fields produced by changing electric current. It does not convert one form of energy to another but rather transforms electric potential and current into higher or lower intensity.
Force on conductor is proportional to:
-Length of conductor -Strength of magnetic field -Size of current F=BIL
What are the components of a Simple DC Motor?
1. Armature or rotor 2. Commutator 3. Field Magnet 4. DC power supply
What are the components of a Simple AC Generator? (3)
1. Field magnet- part of a generator that produces magnetic field 2. Armature- Part in which voltage is induced 3. Slip rings- Bring generating alternating current to load
What are all the components in x-ray circuit necessary to supply electrical power to the x-ray tube? Referred to as?
1. High Voltage Transformer 2. Filament Transformer 3. Voltage rectification Referred to as: -Single phase -Three phase -High Frequency
What does the Fleming Left Hand Rule and Right Hand Rule state?
1. Whenever a current carrying conductor comes under a magnetic field, there will be a force acting on the conductor 2. If a concuctor is forcefully brought under a magnetic field there will be an induced current in that conductor 3. In both of the phenomenon there is a relation between magnetic field, electric current and force 4. This relation directionally determined by John Ambrose Flemming in late 19th century
There are 125 turns on the primary side of a transformer and 900,000 turns on the secondary side. If 110 V AC is supplied to the primary winding, what is the voltage induced in the secondary winding? Vs/Vs=Ns/Np
=110V(900,000/125) =110(720)V =79200V =79.2KV
A "_______-______" transformer is an electromagnet with a ferromagnetic core bent around so that it forms a continuous loop. No end surfaces from which ferromagnetic field lines can escape, therefore magnetic field tends to be confined to the loop of the magnetic core material
A "closed-core" transformer is an electromagnet with a ferromagnetic core bent around so that it forms a continuous loop. No end surfaces from which ferromagnetic field lines can escape, therefore magnetic field tends to be confined to the loop of the magnetic core material
A _____-____ transformer decreases voltage from primary to secondary coil Increases current in same proportion -voltage halved, current doubled Has more turns in primary Used in filament portion of x-ray circuit to decrease voltage to filament
A "step-down" transformer decreases voltage from primary to secondary coil Increases current in same proportion -voltage halved, current doubled Has more turns in primary Used in filament portion of x-ray circuit to decrease voltage to filament
A _____-__ transformer increases voltage from primary to secondary coil Decreases current in same proportion -voltage doubled, current halved Has more turns in secondary than primary Used in x-ray circuit to increase voltage to kilovoltage level necessary for x-ray production
A "step-up" transformer increases voltage from primary to secondary coil Decreases current in same proportion -voltage doubled, current halved Has more turns in secondary than primary Used in x-ray circuit to increase voltage to kilovoltage level necessary for x-ray production
A ___________ is a device which converts variations of current and voltage in a primary circuit into variations of current and voltage in a secondary circuit. Operates on principles of mutual induction Requires alternating current
A "transformer" is a device which converts variations of current and voltage in a primary circuit into variations of current and voltage in a secondary circuit. Operates on principles of mutual induction Requires alternating current
A practical electric motor uses many turns of wire for current loop and many _______ to create and external magnetic force
A practical electric motor uses many turns of wire for current loop and many "magnets" to create and external magnetic force
A synchronous motor is used in motors that require _________
A synchronous motor is used in motors that require "clocks" -Hertz=60 cycles/ second -60 seconds per minute -Can be used every 1/60 second or in multiples 1/30, 1/20, 1/15
A synchronous motor rotates at same number of revolutions per second as ________ of power supply
A synchronous motor rotates at same number of revolutions per second as "frequecny" of power supply
AC generator -Through coil current flows in _____ direction -Outside coil current _____ directions
AC generator -Through coil current flows in "same" direction -Outside coil current "changes" directions
An ___________ is an iron core with only one winding of wire around it
An ___________ is an iron core with only one winding of wire around it
In what cases should an autotransformer be used? Would an autotransformer be suitable for x-ray imaging?
An autotrasnformer is used in cases only when small step up or step down is required thus making it unsuitable for x-ray imaging.
An electric current produces ______ motion Example: Motion of compass needle
An electric current produces "mechanical" motion
An electric motor has basically the same components as electric generator but electric energy is supplied to the motor current loop to produce a __________ motion
An electric motor has basically the same components as electric generator but electric energy is supplied to the motor current loop to produce a "mechanical" motion (rotation of loop in magnetic field)
What type of motor can be found in an x-ray tube?
An induction motor
Change in current across a transformer is in the opposite direction from the voltage change but in the same proportion making it an _________ realtionship
Change in current across a transformer is in the opposite direction from the voltage change but in the same proportion making it an "inverse" relationship
Change in voltage directly proportional to the ratio of the number of _____ (windings) of the secondary coil (Ns) to the number of _____ in the primary coil (Np)
Change in voltage directly proportional to the ratio of the number of "turns" (windings) of the secondary coil (Ns) to the number of "turns" in the primary coil (Np)
Current Step-Up Transformer Current on secondary side (Is) is _____ than current on primary side (Ip) Current Step-Down Current on secondary side is ______ than primary side
Current Step-Up Transformer Current on secondary side (Is) is "smaller" than current on primary side (Ip) Current Step-Down Current on secondary side is "larger" than primary side
Current produced in rotor winding by ________
Current produced in rotor winding by induction
Effect of Transformer Law on Current Is/Ip=Np/Ns or Is/Ip=__/__
Effect of Transformer Law on Current Is/Ip=Np/Ns or Is/Ip=Vp/Vs
Electric current is supplied externally through a _________
Electric current is supplied externally through a "commutator"
Electromagnets around rotors energized in sequence produce changing _______ ____
Electromagnets around rotors energized in sequence produce changing "magnetic field"
Electromagnets being energized in sequence, rotor begins to rotate, trying to bring magnetic field into _________
Electromagnets being energized in sequence, rotor begins to rotate, trying to bring magnetic field into "alignment"
True or False The principle of operation for an electric generator and an electric motor is very different
False The principle of operation for an electric generator and an electric motor is the same
True or false A transformer will operate only with an " direct (changing) current "
False A transformer will operate only with an " alternating (changing) current "
true or False An auto transformer us used only where large difference between and input and out voltage
False An auto transformer us used only where large difference between and input and out voltage
True or False There are separate windings on an autotransformer
False Single winding acts as both primary and secondary windings. The one winding varies both voltage and current
Ferromagnetic core of a closed-core transformer is not a single piece but rather is built out of laminated layers of ____. Layering helps reduce energy losses, resulting in greater efficiency.
Ferromagnetic core of a closed-core transformer is not a single piece but rather is built out of laminated layers of "iron". Layering helps reduce energy losses, resulting in greater efficiency.
Fleming Left Hand Rule A force tends to move the conductor from ____ concentrated magnetic field to ____ concentrated
Fleming Left Hand Rule A force tends to move the conductor from more concentrated magnetic field to less concentrated
Fleming Left Hand Rule The movement, magnetic field and the current are all at _____ angles to each other
Fleming Left Hand Rule The movement, magnetic field and the current are all at "right" angles to each other
Fleming Left Hand Rule True or False If a horizontal magnetic field is applied externally to the conductor, these two magnetic fields will interact with each other
Fleming Left Hand Rule True If a horizontal magnetic field is applied externally to the conductor, these two magnetic fields will interact with each other
Fleming Left Hand Rule When electric current flows through a conductor, a _______ ____ is induced around it
Fleming Left Hand Rule When electric current flows through a conductor, a "magnetic field" is induced around it
Fleming Left Hand Rule is also known as ______ ______
Fleming Left Hand Rule is also known as "motor effect"
Fleming Right Hand Rule As per Faraday's Law, whenever a conductor moves inside a magnetic field, there will be an induced ________ in it
Fleming Right Hand Rule As per Faraday's Law, whenever a conductor moves inside a magnetic field, there will be an induced "current" in it
Recall Fleming Right Hand Rule If this conductor is forcefully moved inside the magnetic field, there will be a relation between the direction and applied force, magnetic field and the electric current
Fleming Right Hand Rule If this conductor is forcefully moved inside the magnetic field, there will be a relation between the direction and applied force, magnetic field and the electric current
For every 10 turns on secondary coil there is turn on primary coil. This means voltage generated in secondary circuit will be __ times the voltage supplied to primary circuit
For every 10 turns on secondary coil there is 1 turn on primary coil. This means voltage generated in secondary circuit will be "10" times the voltage supplied to primary circuit
Generators and motors are important applications of electromagnetic ________
Generators and motors are important applications of electromagnetic "induction"
Generators convert ________ energy into ________ energy. An electrical generator can use work to produce electricity.
Generators convert "mechanical" energy into "electrical" energy. An electrical generator can use work to produce electricity.
Fleming Left Hand Rule If a current carrying conductor is in a magnetic field, the conductor will experience a _____ and move it it is free to do so
If a current carrying conductor is in a magnetic field, the conductor will experience a "force" and move it it is free to do so
If the voltage is double then the current is ________
If the voltage is double then the current is "halved"
In a "two phase" Alternating current Phase A supplies coils _ Phase B supplies coils _
In a "two phase" Alternating current Phase A supplies coils "A" Phase B supplies coils "B"
In a DC generator: -The red and blue legs of the loop are connected to the ____ ____ segments - The two segments are insulated from each other, so that no electrical contact is possible -The two brushes are on opposite sides of the ____ _____, mounted in such a manner that each brush is in contact with only one segment at a time -The _____ _____ is known as the commutator
In a DC generator: -The red and blue legs of the loop are connected to the "split ring" segments - The two segments are insulated from each other, so that no electrical contact is possible -The two brushes are on opposite sides of the "split ring", mounted in such a manner that each brush is in contact with only one segment at a time -The "split ring" is known as the commutator
In a Simple AC Motor a current is passed through the coil, generating a ______ on the coil
In a Simple AC Motor a current is passed through the coil, generating a "torque" on the coil
In a Simple AC Motor since the current is alternating, the motor will run smoothly only at the _________ of the sine wave
In a Simple AC Motor since the current is alternating, the motor will run smoothly only at the "frequency" of the sine wave
In a Simple DC Motor DC is supplied to the _______
In a Simple DC Motor DC is supplied to the "armature"
In electric generator a coil wire is placed in magnetic field between two magnetic poles. The coil is rotated by _________ energy since the coil is moving in the magnetic field a current is induced in the coil of wire.
In electric generator a coil wire is placed in magnetic field between two magnetic poles. The coil is rotated by "mechanical" energy since the coil is moving in the magnetic field a current is induced in the coil of wire.
Increasing voltage automatically _______ current
Increasing voltage automatically decreases current
Induced current in rotor produces ________ ______
Induced current in rotor produces "magnetic field"
Induction Motor A _______ is a part that remains stationary A _______ is a part that rotates
Induction Motor A "stator" is a part that remains stationary A "rotor" is a part that rotates
What is the law for current?
Is/Ip=Np/Ns or Ip/Is=Ns/Np
What is the law for voltage and current?
Is/Ip=Vp/Vs or Ip/Is=Vs/Vp
The turns ratio of a filament transformer is .125 what is the filament current if the current through the primary winding is .8A Is/Ip=Np/Ns
Is=(.8A)(1/.125) 1:.125 turns ratio Is=6.4A
Mechanical motion induces _________ in a coil of wire
Mechanical motion induces "electricity" in a coil of wire Motion of magnet near a coil wire induces electricity in the coil wire
Mechanical motion is the principle on which ________ ___________ operates
Mechanical motion is the principle on which "electric generator" operates
Motors convert ________ energy into ________ energy. An electric motor can use electricity to do work.
Motors convert "electrical" energy into "mechanical" energy. An electric motor can use electricity to do work.
Recall: 1. Autotransformer uses ____ induction. Two currents one against another in the same wire. One winding and varies both voltage and current. 2.A transformer with a turns ratio greater than 1 is a step-up transfromer because the voltage is increased from the ______ side to ______ side. When the turns ratio is less that 1, the transformer is a ____-____ transformer. They both use _____ induction.
Recall: 1. Autotransformer uses "self" induction. Two currents one against another in the same wire. One winding and varies both voltage and current. 2.A transformer with a turns ratio greater than 1 is a step-up transfromer because the voltage is increased from the "primary" side to "secondary" side. When the turns ratio is less that 1, the transformer is a "step-down" transformer. They both use "mutual" induction.
Simple AC Motor is a sychronous motor -current fed to ______ causes it to rotate -rotates at same number of revolutions per second as frequency of power supply -Used in motors requiring ______ (hertz=60 cycles/second, 60 seconds per min., can be used every 1/60 second or in multiples: 1/30, 1/15, 1/20)
Simple AC Motor is a sychronous motor -current fed to "armature" causes it to rotate -rotates at same number of revolutions per second as frequency of power supply -Used in motors requiring clocks (hertz=60 cycles/second, 60 seconds per min., can be used every 1/60 second or in multiples: 1/30, 1/15, 1/20)
Simple DC Motor work similar to ________
Simple DC Motor work similar to "generator"
Standard Voltage US: ___ voltz @ 60 Hz Europe: 220 @ __ Hz
Standard Voltage US: 110 voltz @ 60 Hz Europe: 220 @ 50 Hz
The induction motor has a rotating _____ which is a shaft made of bars of copper and soft iron fabricated into one mass. The external magnetic fiel is supplied by several fixed electromagnets callled _______
The induction motor has a rotating "rotor" which is a shaft made of bars of copper and soft iron fabricated into one mass. The external magnetic field is supplied by several fixed electromagnets called "stators"
Which side does the induction motor power?
The induction motor powers the anode side of the x-ray tube
The magnetic field of the electric induction motor attempts to align itself with magnetic field of external _____________
The magnetic field of the electric induction motor attempts to align itself with magnetic field of external "electromagnets"
The net effect of electric generator is to convert ________ energy into ________ energy
The net effect of electric generator is to convert "mechanical" energy into "electrical" energy
Why is the net effect of electric generators not 100% efficient?
The net effect of electrical generators is not 100% efficient because of losses in mechanical moving parts and heat loss caused by resistance in electrical components
The commutator of a simple DC motor reversed the current flow each 1/2 rotation what is the result of this?
The result is that the armature rotates contiuously
Transformer Law Vs/Vp=__/__
Transformer Law Vs/Vp=Ns/Np (Ns/Np is known as turns ratio of transformer
Transformer changes intensity of alternating _________ and _______
Transformer changes intensity of alternating "voltage" and "current"
True or False Increasing voltage automatically leads to a decrease in current
True
True or False A simple AC motor has a synchronous motor
True A simple AC motor has a synchronous motor
True or False An AC motor works similar to a DC motor
True An AC motor works similar to a DC motor
True or False Because there is not commutator in a AC motor the current reverses direction
True Because there is not commutator in a AC motor the current reverses direction
True or False Changing current in primary coil induces changing current in secondary coil
True Changing current in primary coil induces changing current in secondary coil
Simple AC Motor True or False If a high current which must flow through the rotating contacts, sparking and heating at those contacts can waste energy and shorten the lifetime of the motor
True If a high current which must flow through the rotating contacts, sparking and heating at those contacts can waste energy and shorten the lifetime of the motor
True or False No electric current is passed to the rotor
True No electric current is passed to the rotor
True or False Autotransformer has two closed cores making it more efficient than closed-core transformer. For this reason it is the transformer that is most currently used.
True Shell-type transformer has two closed cores making it more efficient than closed-core transformer. For this reason it is the transformer that is most currently used.
Turns ratio greater than 1 is a _____-__ transformer because voltage is increased from primary to secondary Turns ratio less than 1 is _____-_____ transformer
Turns ratio greater than 1 is a "step-up" transformer because voltage is increased from primary to secondary Turns ratio less than 1 is "step-down" transformer
Type of Transformers A _____________ -Iron core with single winding -- Functions as both primary and secondary windings -Used in x-ray circuit to provide small increase in voltage before step-up transformer -Operates on principle of of self induction
Type of Transformers A auto transformer -Iron core with single winding -- Functions as both primary and secondary windings -Used in x-ray circuit to provide small increase in voltage before step-up transformer -operates on of self induction
Types of Transformer A ____-____ transformer -most advanced -Primary and Secondary both wound around center -Used in most x-ray equipment
Types of Transformer A "shell-type" transformer -most advanced -Primary and Secondary both wound around center -Used in most x-ray equipment
Types of Transformers ___ ____ transformer -Two highly insulated coils --Side-by-side --Simplest and most inefficient
Types of Transformers "Air core" transformer -Two highly insulated coils --Side-by-side --Simplest and most inefficient
Types of Transformers A _____ _____ transformer -More efficient than open core -Reduces transformer loss -Reduces leakage flux
Types of Transformers A "closed-core" transformer -More efficient than open core -Reduces transformer loss -Reduces leakage flux
Types of Transformers A _____ _____ transformer -More efficient -Difference is iron core inserted into each coil -Core becomes magnetized which increases magnetic strength
Types of Transformers A "open core" transformer -More efficient -Difference is iron core inserted into each coil -Core becomes magnetized which increases magnetic strength
Voltage change across transformer is proportional to ______ _______
Voltage change across transformer is proportional to "turns ratio"
What is the law for voltage?
Vs/Vp=Ns/Np
Provide example of mechanical energy
Water flowing over water wheel or stream flowing past turbine blade
Waveform of DC Generator Moving from one commutator segement to the other, cause the current to flow in the _______ direction rather than becoming _________. The current starts at zero, rises to max, and falls back to zero twice for ____ ______ of the loop
Waveform of DC Generator Moving from one commutator segement to the other, cause the current to flow in the "positive" direction rather than becoming "negative". The current starts at zero, rises to max, and falls back to zero twice for "each rotation" of the loop
When a secondary coil is wound around the other side almost all magnetic field produced by primary coil passes through center of ________ coil
When a secondary coil is wound around the other side almost all magnetic field produced by primary coil passes through center of "secondary" coil
When electric current passes through a coil in a magnetic field, the magnetic force produces a _____ which turns the DC motor
When electric current passes through a coil in a magnetic field, the magnetic force produces a "torque" which turns the DC motor