Class Wiki - User contributions [en]

Transformer example problem

2010-01-20T06:14:27Z

Alexroddy: /* Reviewers: */

===Problem:===
An ideal transformer with a 300 turn primary connected to a 480 V, 60 Hz supply line needs to output 120 V from the secondary. If a 100 Ω resistor is connected across the secondary, determine: A) How many turns the secondary must have to output the desired voltage. B) The current through the resistor, C)The current drawn through the primary. D) The maximum flux in the core of the transformer

[[Image:Transformer_EMEC.png]]

===Solution:===
====Part A:====
The ratio of primary voltage to secondary voltage is directly proportional to the ratio of number of turns on the primary to number of turns on the secondary:
 
 
<math>\frac{V_1}{V_2} = \frac{N_1}{N_2}</math>
 
 
Where <math> V_1 = </math>Voltage across primary,
<math>V_2 = </math>Voltage across secondary,
<math>N_1 = </math> Number of turns in primary,
<math>N_2 = </math> Number of turns in secondary

<math>\frac{480 \ volts}{120 \ volts} = \frac{300 \ turns}{N_2}</math>
 
 
To solve for the number of turns required for the secondary, the equation is rearranged solving for <math>N_2 = </math>:
 
 
<math>N_2 = \frac{300 \cdot 120}{480} \Rightarrow N_2 = 75 \ turns </math>

====Part B:====
The voltage across the secondary is given in the problem statement as 120 volts. Using ohms law, <math> V =i \cdot R </math>, we can solve for the current in the loop (<math> i_2 </math> ).
 
<math> i_2 = \frac{V_2}{R_L}</math>
 
Where <math> i_2 = </math> Current through secondary,
<math>V_2 = </math>Voltage across secondary,
<math>R_L = </math> Load Resistor (<math>R_L = </math> 100 Ω)
 
 
<math> i_2 = \frac{120 \ volts}{100 \ \Omega} \Rightarrow i_2 = 1.2 \ A </math>

====Part C:====
The ratio of primary current to secondary current is inversely proportional to the ratio of number of turns on the primary to number of turns on the secondary:
 
 
<math>\frac{i_1}{i_2} = \frac{N_2}{N_1}</math>
 
Where <math> i_1 = </math>Current in primary,
<math>i_2 = </math>Current in secondary,
<math>N_1 = </math> Number of turns in primary,
<math>N_2 = </math> Number of turns in secondary

<math>\frac{i_1}{1.2 \ A} = \frac{75 \ turns}{300 \ turns}</math>

Rearranging to solve for <math>i_1 </math>:

<math>\ i_1 = i_2 \cdot \frac{N_2}{N_1} \Rightarrow 1.2 A \cdot \frac{75 \ turns}{300 \ turns} \Rightarrow i_1 = .3 \ A</math>

====Part D:====
The induced emf of the secondary can be calculated by:
<math> V_2 = 4.44 \ \cdot \mathit{f} \cdot N_2 \cdot \Phi_m \ \angle 0^\circ </math><ref>Guru and Huseyin, ''Electric Machinery and Transformers'', 3rd ed. (New York: Oxford University Press, 2001), 209.</ref>
Solving for <math> \Phi_m </math>, we can calculate the maximum flux in the core:
<math> \ \Phi_m = \frac{V_2}{4.44 \cdot \mathit{f} \cdot N_2} </math>

Where <math> \Phi_m \ = </math>max flux in core,
<math>V_2 = </math>Voltage across secondary,
<math>\mathit{f} = </math> Frequency of line,
<math>N_2 = </math> Number of turns in secondary

<math> \ \Phi_m = \frac{120}{4.44 \cdot 60 \ Hz \cdot 75} \Rightarrow \Phi_m = 6.006 \ mWb </math>

==References:==
<references/>

==Authors:==
[[Tim Rasmussen]]
==Reviewers:==
Wesley Brown

Alex Roddy

==Readers:==

Transformer example problem

2010-01-20T06:14:10Z

Alexroddy: /* Reviewers: */

AC Motors

2010-01-10T20:47:15Z

Alexroddy: /* Basic Parts and Principles */

This is an article in progress

== Basic Parts and Principles ==

Electric motors convert electrical energy into mechanical motion by using magnetic forces to accelerate objects. Electricity comes in two flavors: AC and DC<ref>http://fweb/class-wiki/index.php/AC_vs._DC</ref>. Therefore, electric motors need to be able to utilize at least one of these in order to operate. As a general rule, AC and DC motors are constructed using slightly different parts because of the different behavior of the types of electricity. Lets first look at the parts in a generic AC motor and then discuss the role they play in making motion.

AC motors consist mainly of a stator and a armature<ref>http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motorac.html</ref>, often called the rotor. The stator is fixed inside the motor. Stators are almost always made using tightly wound wire in order to yield a high magnetic flux density. The second part is the rotor, which rotates to provide movement to whatever application is desired. The rotor also uses wound wire, through which current flows. In order to get this current to the rotor without tangling wires around the rotor, metal slip rings are used to complete the circuit<ref>http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motorac.html</ref>.

Magnetic flux is created when current passes through the wires. Since the motor uses alternating current, the magnetic field will alternate polarity. Both the stator and rotor produce magnetic fields. The interaction between magnetic fields says that opposite poles attract while like poles repel. Electric motors use this behavior to produce rotation. When the poles of the stator and rotor are the same, the force will push the two apart. Similarly, the stator and rotor will be pulled together. Motors use both of these simultaneously to impart motion to the rotor, to which the output shaft is attached.

==Synchronous AC Motors==
Synchronous motors are termed synchronous because they inherently run at a constant velocity which is synchronized with the frequency of the AC power supply. These motors contain two basic components: A rotor - the components that rotate, and a stator - the outside shell of the motor. The rotor can be made from either a permanent magnet or winding powered by a DC power source. When powered, this winding operates as a permanent magnet. The stator holds the armature winding which creates a rotating magnetic field inside the motor. The armature winding can be either either single or multi-phase. Similarly, the rotor has 2 poles in the simplest case, but can have many more depending on the application.
The rotational velocity of a synchronous motor is a function of the number of pairs of poles and is always a
<ref>http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee2/bdeee2_1-4.aspx</ref>
<ref>http://www.allaboutcircuits.com/vol_2/chpt_13/2.html</ref>
<ref>http://www.acsynchronousmotors.com/</ref>

===References===
<references/>

===Authors:===

===Reviewers:===

===Readers:===

AC Motors

2010-01-10T20:44:34Z

Alexroddy:

This is an article in progress

== Basic Parts and Principles ==

Electric motors convert electrical energy into mechanical motion by using magnetic forces to accelerate objects. Electricity comes in two flavors: AC and DC<ref>http://fweb/class-wiki/index.php/AC_vs._DC</ref>. Therefore, electric motors need to be able to utilize at least one of these in order to operate. As a general rule, AC and DC motors are constructed using slightly different parts because of the different behavior of the types of electricity. Lets first look at the parts in a generic AC motor and then discuss the role they play in making motion.

AC motors consist mainly of a stator and a rotor, sometimes called the armature.<ref>http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motorac.html</ref> The stator is fixed inside the motor. Stators are almost always made using tightly wound wire in order to yield a high magnetic flux density. The second part is the rotor, which rotates to provide movement to whatever application is desired. The rotor also uses wound wire, through which current flows. In order to get this current to the rotor without tangling wires around the rotor, metal slip rings are used to complete the circuit<ref>http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motorac.html</ref>.

Magnetic flux is created when current passes through the wires. Since the motor uses alternating current, the magnetic field will alternate polarity. Both the stator and rotor produce magnetic fields. The interaction between magnetic fields says that opposite poles attract while like poles repel. Electric motors use this behavior to produce rotation. When the poles of the stator and rotor are the same, the force will push the two apart. Similarly, the stator and rotor will be pulled together. Motors use both of these simultaneously to impart motion to the rotor, to which the output shaft is attached.

==Synchronous AC Motors==
Synchronous motors are termed synchronous because they inherently run at a constant velocity which is synchronized with the frequency of the AC power supply. These motors contain two basic components: A rotor - the components that rotate, and a stator - the outside shell of the motor. The rotor can be made from either a permanent magnet or winding powered by a DC power source. When powered, this winding operates as a permanent magnet. The stator holds the armature winding which creates a rotating magnetic field inside the motor. The armature winding can be either either single or multi-phase. Similarly, the rotor has 2 poles in the simplest case, but can have many more depending on the application.
The rotational velocity of a synchronous motor is a function of the number of pairs of poles and is always a
<ref>http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee2/bdeee2_1-4.aspx</ref>
<ref>http://www.allaboutcircuits.com/vol_2/chpt_13/2.html</ref>
<ref>http://www.acsynchronousmotors.com/</ref>

===References===
<references/>

===Authors:===

===Reviewers:===

===Readers:===

AC Motors

2010-01-10T20:32:27Z

Alexroddy:

This is an article in progress

== Basic Parts and Principles ==

Electric motors convert electrical energy into mechanical motion by using magnetic forces to accelerate objects. Electricity comes in two flavors: AC and DC. Therefore, electric motors need to be able to utilize at least one of these in order to operate. As a general rule, AC and DC motors are constructed using slightly different parts because of the different behavior of the types of electricity. Lets first look at the parts in a generic AC motor and then discuss the role they play in making motion.

AC motors consist mainly of a stator and a rotor. The stator is fixed inside the motor. Stators are almost always made using tightly wound wire in order to yield a high magnetic flux density. The second part is the rotor, which rotates to provide movement to whatever application is desired. The rotor also uses wound wire, through which current flows. In order to get this current to the rotor without tangling wires around the rotor, metal slip rings are used to complete the circuit.

Magnetic flux is created when current passes through the wires. Since the motor uses alternating current, the magnetic field will alternate polarity. Both the stator and rotor produce magnetic fields. The interaction between magnetic fields says that opposite poles attract while like poles repel. Electric motors use this behavior to produce rotation. When the poles of the stator and rotor are the same, the force will push the two apart. Similarly, the stator and rotor will be pulled together. Motors use both of these simultaneously to impart motion to the rotor, to which the output shaft is attached.

References have yet to be added

==Synchronous AC Motors==
Synchronous motors are termed synchronous because they inherently run at a constant velocity which is synchronized with the frequency of the AC power supply. These motors contain two basic components: A rotor - the components that rotate, and a stator - the outside shell of the motor. The rotor can be made from either a permanent magnet or winding powered by a DC power source. When powered, this winding operates as a permanent magnet. The stator holds the armature winding which creates a rotating magnetic field inside the motor. The armature winding can be either either single or multi-phase. Similarly, the rotor has 2 poles in the simplest case, but can have many more depending on the application.
The rotational velocity of a synchronous motor is a function of the number of pairs of poles and is always a
<ref>http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee2/bdeee2_1-4.aspx</ref>
<ref>http://www.allaboutcircuits.com/vol_2/chpt_13/2.html</ref>
<ref>http://www.acsynchronousmotors.com/</ref>

===References===
<references/>

===Authors:===

===Reviewers:===

===Readers:===

AC Motors

2010-01-10T19:37:38Z

Alexroddy:

This is an article in progress

Electric motors convert electrical energy into mechanical motion by using magnetic forces to accelerate objects. Electricity comes in two flavors: AC and DC. Therefore, electric motors need to be able to utilize at least one of these in order to operate. As a general rule, AC and DC motors are constructed using slightly different parts because of the different behavior of the types of electricity. Lets first look at the parts in a generic AC motor and then discuss the role they play in making motion.

AC motors consist mainly of a stator and a rotor. The stator is fixed inside the motor. Stators are almost always made using tightly wound wire in order to yield a high magnetic flux density. The second part is the rotor, which rotates to provide movement to whatever application is desired. The rotor also uses wound wire, through which current flows. In order to get this current to the rotor without tangling wires around the rotor, metal slip rings are used to complete the circuit.

Magnetic flux is created when current passes through the wires. Since the motor uses alternating current, the magnetic field will alternate polarity. Both the stator and rotor produce magnetic fields. The interaction between magnetic fields says that opposite poles attract while like poles repel. Electric motors use this behavior to produce rotation. When the poles of the stator and rotor are the same, the force will push the two apart. Similarly, the stator and rotor will be pulled together. Motors use both of these simultaneously to impart motion to the rotor, to which the output shaft is attached.

References have yet to be added

==Synchronous AC Motors==
Synchronous motors are termed synchronous because they inherently run at a constant velocity which is synchronized with the frequency of the AC power supply. These motors contain two basic components: A rotor - the components that rotate, and a stator - the outside shell of the motor. The rotor can be made from either a permanent magnet or winding powered by a DC power source. When powered, this winding operates as a permanent magnet. The stator holds the armature winding which creates a rotating magnetic field inside the motor. The armature winding can be either either single or multi-phase. Similarly, the rotor has 2 poles in the simplest case, but can have many more depending on the application.
The rotational velocity of a synchronous motor is a function of the number of pairs of poles and is always a
<ref>http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee2/bdeee2_1-4.aspx</ref>
<ref>http://www.allaboutcircuits.com/vol_2/chpt_13/2.html</ref>
<ref>http://www.acsynchronousmotors.com/</ref>

===References===
<references/>

===Authors:===

===Reviewers:===

===Readers:===

Alex Roddy

2010-01-08T21:43:45Z

Alexroddy:

== Contact ==

Cell phone: (740) 352 - 1455

email: alexander.roddy@wallawalla.edu

== Published Articles ==

== Current Projects ==

== Helpful Resources ==

Alex Roddy

2010-01-08T21:43:23Z

Alexroddy: New page: == Contact == Cell phone: (740) 352 - 1455 email: alexander.roddy@wallawalla.edu == Published Articles == == Current Projects == == Helpful Resources ==

== Contact ==

Cell phone: (740) 352 - 1455

email: alexander.roddy@wallawalla.edu

== Published Articles ==

== Current Projects ==

== Helpful Resources ==

Points

2010-01-08T07:03:22Z

Alexroddy: /* Who's article is it anyways: Where everything is made up and the points don't matter! */

==Points earned==
===Who's article is it anyways: Where everything is made up and the points don't matter!===
(If you missed the joke you are required to go watch Who's line is it anyways right now!)

1. Lau, Chris - 67/6 points

2. Anderson, Tyler - <math>\infin + 1</math>

3. Sell, Andrew − QZǼMΩ

4. Griffith, Will - <math>\infin * i</math>

5. Brown, Wesley - 0

6. Rasmussen, Tim - 18.5

7. Roddy, Alex - 0

Electromechanical Energy Conversion

2010-01-07T18:07:11Z

Alexroddy:

==Class 2010==
#[[Eric Clay]]
#[[Jason Osborne]]
#Tim Van Arsdale
#Kirk Betz
#Corneliu Turturica
#Jimmy Apablaza
#[[Will Griffith]]
#[[Greg Fong]]
#[[Tyler Anderson]]
#Andrew Sell
#[[Lau, Chris]]
#Kyle Lafferty
#Matthew Fetke
#Wesley Brown
#[[Erik Biesenthal]]
#[[Jodi Hodge]]
#[[David Robbins]]
#[[Amy Crosby]]
#[[Tim Rasmussen]]
#[[Kevin Starkey EMEC]]
#[[John Hawkins]]
#[[Alex Roddy]]

===Links===
[[Rules]]

==Articles==
None published to date
==Points earned==
1. Lau, Chris - 61/6 points
==Draft Articles==
These articles are not ready for reading and error checking. They are listed so people will not simultaneously write about similar topics.
* [[Ferromagnetism]]