<a href="https://www.controleng.com/single-article/innovations-in-electric-motor-technology-the-first-100-years/6b3f05d5143571debce17000aa83cb07.html">Electro motor technology</a> will not disappear. it is still in use today ... even electro motors currently have a lot of development in advanced technology, before we know more about the electro motors, I will introduce the basic electro motor theory formulas first,this theory is the beginning where we learn about electro-motor knowledge, if you are interested in knowing the theory of rolling dynamo coils, this is an early stage theory and we have to know it


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<center><img class=" aligncenter" src="https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Electric_motor.gif/220px-Electric_motor.gif" width="363" height="363" /></center><br/>

<a href="https://en.wikipedia.org/wiki/Electric_motor">source image</a>

<strong>PHASE</strong>
positively charged electricity is called phase and negatively charged is called 0. There are 3 types of PHASE in the electro motor

1. phase there are 2 cables; 1 (+) and 1` (-)
2. phase there are 3 cables; 2 (+) and 1 (-)
3. phase there are 4 cables; 3 (+) and 1 (-)

<strong>Power Factor (PF)</strong>
a factor of the flow of exchange is the ratio of Watts of watt meters with Volts multiplied by amperes from the measurement of volt meters and amperes meters
<p><center><a href="https://www.rapidtables.com/electric/Power_Factor.html">PF = Cos  Q= W/(V x A)</a></center></p>
<strong>Randemen Motor (Motor efficiency)</strong>
Randemen or yield is the ratio between the power produced by the motor on its axis (output) and the power required at the terminal (input) in the same unit expressed in percent (%)
<center><em>randemen motor</em> =  (output / input) x  100%</center></p>
<strong>Cycle</strong>
the number of complete changes (periods) in the flow of exchange that occur in one second, called 1 cycle.
unit :           <em> Cycle per second (c / s)</em>
<em>Period per second (p / s)</em>
<em>Herz (Hz)</em>
</p>
<strong>conductivity</strong>
in Electro Motors is the ability of a substance to flow an electric current. The electrical current flowing in a conductor wire will experience resistance from the conductor molecule itself.
if the resistance of a large molecule small conductivity
if the resistance of a small molecule Big conductivity  ,
<center>G= 1/R                         R=1/G</center></p>
<center><a href="https://www.translatorscafe.com/unit-converter/en/electric-conductance/1-7/siemens-mho/"> conductivity is expressed in units of  mho [℧] (siemens)</a></center></p>
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 <strong>Resistans</strong><strong> Resisvity</strong>
 Resistance of a metal, is the value in a state of 1 meter long with a cross-sectional area of 1 millimeter at a temperature of 0°  Celsius.
type resistance is expressed in Rho (ρ) units


Resistance metal list at 15° Celsius
Silver                    0.016
Copper                 0.0172
aluminum           0.030
nickel                    0.12
pure iron              0.12
hard steel            0.45
brass                     0.08
Manganin           0.4
The R value of each conductor can be found by formula.
<center><a href="https://www.engineeringtoolbox.com/resistance-resisitivity-d_1382.html"><i>R = ρ l / A  </i></a></center></p>
R = value of resistance
ρ = resistivity resistance 15°C
<a href="https://www.engineeringtoolbox.com/resistance-resisitivity-d_1382.html"><i> l</i></a> = length of conductor in meters
A = millimeter cross section

<center><img class="size-medium aligncenter" src="https://upload.wikimedia.org/wikipedia/commons/5/58/Stator_and_rotor_by_Zureks.JPG" width="2412" height="1709" /></center><br/>

<a href="https://en.wikipedia.org/wiki/Electric_motor">source image</a>

<strong>The working principle of an electric motor</strong>

<img class="alignnone  wp-image-46" src="https://thunter.000webhostapp.com/wp-content/uploads/2018/08/2018-08-29-300x128.jpeg" alt="" width="649" height="277" /><br/>

the motor on the shaft will rotate, if placed between the magnetic field by changing the electric current in the magnetic field stator will change and cause the roror to rotate on its axis.

         motor with 2 poles                           motor with 4 poles

<img class="alignnone  wp-image-47" src="https://thunter.000webhostapp.com/wp-content/uploads/2018/08/Image-2018-08-29-at-23.30.08-300x133.jpeg" alt="" width="636" height="282" /><br/>

motor with 2 poles in 1 cycle 2 changes occur  positive and negative
motor with 4 poles in 1 cycle 4 changes occur   2 positives and 2 negatives

reference <a href="https://www.engineeringtoolbox.com/">1 </a>  , <a href="https://en.wikipedia.org/wiki/Electric_motor">2</a> , <a href="https://www.controleng.com/single-article/innovations-in-electric-motor-technology-the-first-100-years/6b3f05d5143571debce17000aa83cb07.html">3</a>


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