Class Wiki - User contributions [en]

Ideal Transformer Example

2010-01-20T18:34:36Z

Aric.vyhmeister: /* Readers */

An idea transformer has a 275-turn primary and 825-turn secondary. The primary is connected to a 200-V, 60-Hz source. The secondary supplies a load of 5 A at a lagging power factor of 0.5. Find the turns-ratio, the current in the primary, the power supplied to the load, and the flux in the core.

===Solution===
(A) <math>\ {turns-ratio}=\frac{N_{1}}{N_{2}}</math>
<math>\ =\frac{275}{825}</math>
<math>\ =0.333</math>

(B) Because <math>\ {I_{2}}=5 A</math>, the current in the primary is...

<math>\ {I_{1}}=\frac{I_{2}}{turns-ratio}</math>
<math>\ =\frac{5}{0.333}</math>
<math>\ =15 A</math>

(C) <math>\ {V_{2}}=\frac{V_{1}}{turns-ratio}</math>
<math>\ =\frac{200}{0.333}</math>
<math>\ =600 V</math>

Therefore, the power supplied to the load is...

<math>\ {P_{L}}=V_{2} I_{2}\cos(\theta)</math>
<math>\ =600 * 5 * 0.5</math>
<math>\ =1500 W</math>

(D) <math>\ {\phi_{m}}=\frac{E_{1}}{4.44 f N_{1}}</math>
<math>\ =\frac{V_{1}}{4.44 f N_{1}}</math>
<math>\ =\frac{200}{4.44 * 60 * 275}</math>
<math>\ =2.73 mWb</math>

==Author==
[[Kyle Lafferty]]

==Reviewers==
Aric Vyhmeister

==Readers==
Aric Vyhmeister

Ideal Transformer Example

2010-01-20T18:34:19Z

Aric.vyhmeister: /* Reviewers */

Ohm's Law and Reluctance

2010-01-11T18:03:07Z

Aric.vyhmeister: /* Ohm's Law */

==Ohm's Law==

Electric circuits share many of the same characteristics as magnetic circuits. One of the most important and fundamental equations describing electric circuits is Ohm’s Law. Georg Ohm, a German physicist, published this famous equation in 1827, drawing significant influence from Fourier’s previous work in heat conduction.

Ohm’s Law states that the resistance of a conductor is constant and inversely proportional to the current running through the conductor and directly proportional to the voltage across it, or expressed mathematically as

<center><math>R=\frac{V}{I}</math></center>

The SI units for resistance are the Ohm (<math>\Omega</math>), voltage is expressed in volts (V) and current is measured in amperes (A).

Expressed differently, the current density J (A/<math>m^2</math>) is proportional to the product of conductivity sigma (V/m) and the electric field E (siemens/meter, s/m), or

<center><math>J=\sigma E</math></center>

==Reluctance==

Now, consider a material of very high permeability with flux <math>\Phi</math> running through it and separated by a very small gap of area A, where the flux flows through this gap as if it were free space. The flux density crossing this gap is B. Therefore

<center><math>\Phi=BA</math></center>

The magnetic field intensity can be approximated by <math>H=\frac{B}{\mu_0}</math>

The reluctance of this gap is analogous to the resistance described by Ohm’s Law, where it is the ratio of the magnetomotive force to the flux, or

<center><math>\R = \frac{F}{\phi}</math></center>

Ohm's Law and Reluctance

2010-01-11T16:40:01Z

Aric.vyhmeister: /* Ohm's Law */

==Ohm's Law==

Electric circuits share many of the same characteristics as magnetic circuits. One of the most important and fundamental equations describing electric circuits is Ohm’s Law. Georg Ohm, a German physicist, published this famous equation in 1827, drawing significant influence from Fourier’s previous work in heat conduction.

Ohm’s Law states that the resistance of a conductor is constant and inversely proportional to the current running through the conductor and directly proportional to the voltage across it, or expressed mathematically as

<center><math>R=\frac{V}{I}</math></center>

The SI units for resistance are the Ohm (omega), voltage is expressed in volts (V) and current is measured in amperes (A).

Expressed differently, the current density J (amperes/m^2) is proportional to the product of conductivity sigma (V/m) and the electric field E (siemens/meter), or

<center><math>J=\sigma E</math></center>

Now, consider a material of very high permeability with flux phi running through it and separated by a very small gap of area A, where the flux flows through this gap as if it were free space. The flux density crossing this gap is B. Therefore

<center><math>\Phi = BA</math></center>

The magnetic field intensity can be approximated by H = B/muzero

The reluctance of this gap is analogous to the resistance described by Ohm’s Law, where it is the ratio of the magnetomotive force to the flux, or

<center><math>\R = \frac{F}{\phi}</math></center>

Ohm's Law and Reluctance

2010-01-11T16:28:07Z

Aric.vyhmeister:

==Ohm's Law==

Electric circuits share many of the same characteristics as magnetic circuits. One of the most important and fundamental equations describing electric circuits is Ohm’s Law. Georg Ohm, a German physicist, published this famous equation in 1827, drawing significant influence from Fourier’s previous work in heat conduction.

Ohm’s Law states that the resistance of a conductor is constant and inversely proportional to the current running through the conductor and directly proportional to the voltage across it, or expressed mathematically as

R = V/I :<math>\R =

The SI units for resistance are the Ohm (omega), voltage is expressed in volts (V) and current is measured in amperes (A).

Expressed differently, the current density J (amperes/m^2) is proportional to the product of conductivity sigma (V/m) and the electric field E (siemens/meter), or

J = sigma*E.

Now, consider a material of very high permeability with flux phi running through it and separated by a very small gap of area A, where the flux flows through this gap as if it were free space. The flux density crossing this gap is B. Therefore

Phi = BA

The magnetic field intensity can be approximated by H = B/muzero

The reluctance of this gap is analogous to the resistance described by Ohm’s Law, where it is the ratio of the magnetomotive force to the flux, or

R = F/phi

Ohm's Law and Reluctance

2010-01-11T06:54:17Z

Aric.vyhmeister: New page: This article introduces Ohm's Law and reluctance, its magnetic circuit analog.

This article introduces Ohm's Law and reluctance, its magnetic circuit analog.

Electromechanical Energy Conversion

2010-01-11T06:53:22Z

Aric.vyhmeister: /* Draft Articles */

[[Rules]]

[[Class Roster]]

[[Points]]

==Articles==
None published to date

==Questions==

What do we do when we are finished with the draft and ready to publish?

==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]]
* [[Magnetic Circuits]]
* [[Gauss Meters]]
* [[Ampere's Law]]
* [[DC Motor]]
* [[AC vs. DC]]
* [[An Application of Electromechanical Energy Conversion: Hybrid Electric Vehicles]]
* [[AC Motors]]
* [[Fringing]]
* [[Nick_ENGR431_P1|Magnetostatics]]
* [[Example problems of magnetic circuits]]
* [[Magnetic Circuit]]
* [[Ohm's Law and Reluctance]]

Class Roster

2010-01-11T04:10:30Z

Aric.vyhmeister: /* Class of 2010 */

===Class of 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]]
#[[Aric Vyhmeister]]
#[[Nick Christman]]