_Hi, the great steemians, thanks for reading my last post and for upvoting me. Special thank goes to the steemSTEM management team._

This post shall focus on the basic laws of Physic governing the operation of Synchronous Electrical Machines. But before we go into that, lets first consider what Synchronous Electrical Machines are, so that we can have the pre-knowledge of the discussion.

_Lets get started_

# Synchronous Electrical Generator

Synchronous electrical generator also referred to as an Alternator or an AC motor is an electromechanical device that is capable of converting electrical energy contained in the magnetic field to a mechanical energy and can also convert mechanical energy into electrical energy. For example, AC motor converts electrical energy to mechanical energy while AC generator converts mechanical energy into electrical energy in the form of an alternating current (AC) as output.  It is also called a rotating electromagnetic device because it produces a rotating magnetic field in the [stator](https://en.wikipedia.org/wiki/Stator) which is always induced by an AC voltage. The rotating magnetic field produced depends greatly on the speed of the motor. 

In an AC motor, there are two major functional parts; the Stator and the Rotor. The Stator is a stationary electromagnetic coils while a rotor is a movable magnet usually a permanent magnet. The stator is always positioned around the rotor to generate magnetic flux. For an AC motor to function well, it must have it polarities within the rotating magnetic field. An AC motor can be in two phases or three phases. Each phase of an AC motor has a pair of Stator usually connected to sinusoidal AC inputs. 

When current is applied to the stator pair of each phase, a change in phase occurs (two phases motor is designed to rotate at 90 degrees phase difference while three phases motor rotates at 120 degrees phase difference), when this happens, the polarity of the stator pair changes, causing the turning of the magnetic rotor and thereby transforming electrical energy into mechanical energy. The speed of an AC motor depends on the amount current supplied. A table fan is an example of a device that uses an AC motor.

<center>https://cdn.steemitimages.com/DQme2qBhVAajxu2damF3TduhmLPShP5CKKRh2QPEirvtxYN/image.png
[By Abnormaal - Own work, CC BY-SA 3.0](https://commons.wikimedia.org/w/index.php?curid=4087521)</center>

AC motor and AC generator are opposite of each other. The AC generator consists of a loop and an iron coil known as an armature, the loop is always wrapped around an armature. An electromotive force (EMF) is produced due to the change in direction of the loops caused by the change in current direction in the loop. Once there is a constant rotation of the generator, it constantly produces an EMF. The constant rotation of the generator can be achieved through a mechanical means, a windmill, thermal generation plant, hydroelectric plants e.t.c.  

The frequency of an alternating current (can be either 50 Hertz or 60 Hertz) is a number of complete cycles made by currents and/or voltage while changing direction or polarity with time, usually per second. The frequency of an alternating current in Nigeria is 50 Hertz. An AC generator is commonly found in various homes as an alternative power supply.



<center>https://cdn.steemitimages.com/DQmcBbtfZVNCqSGqBGs2jzJqjmFagQzRdSonG2Mtjmsupog/image.png
[By Zureks - Own work, CC BY-SA 3.0, A Stator and Rotor](https://commons.wikimedia.org/w/index.php?curid=4170132)</center>


# The basic laws of Physics governing the operation of Synchronous Electrical Machines

There are for basic laws of Physics that governs the function of Synchronous Electrical Machines, these basic laws include; Electromechanical Energy Conversion, Lenz's law of action and reaction, Faraday's law of electromagnetic induction and Ampere-Biot-Savart's law of electromagnetic induced forces.

_These basic principles shall be explained one after the other, hope I do not shut myself in the leg because there are professors of Electronics on ground to grade me, lol._

**Electromechanical Energy Conversion**
The first law of conservation of energy states that energy can neither be created nor destroyed but can be changed from one form to another. Electromechanical energy conversion process obeys the first law of energy conservation. During electromechanical energy conversion,  some amount of electrical and mechanical energies are supplied into a system as input, the majority of these energies flows out of the system as output, some are stored in the machine while some are dissipated as heat. The algebraic sum of mechanical energy and electrical energy conversion in a system must be equal to zero.

The balance in all forms of energy of a system determines; the efficiency of the system, if the cooling system will be required or not, parameters for designing and construction of machine and critical performance of the system. All motors generate potential difference (EMF) between their terminals, but EMF (back EMF) produced by a motor is considered energy waste. Back EMF increases with increase in the motor speed, it also contributes to the high power consumption of a motor.

<center>https://cdn.steemitimages.com/DQmbnS6KTeB78h38tqUASeP2qkaXY4gPEQ4VopfCWv7D3wK/image.png
[By Funkjoker23 - Own work, CC0](https://commons.wikimedia.org/w/index.php?curid=17634829)</center>

**Lenz's law of action and reaction and Faraday's law of electromagnetic induction**

The Lenz's law of action and reaction can be explained using the third law of motion. Third law of motion state that for two bodies in contact, the action and reaction forces are equal in magnitude but act in opposite directions. Lenz's law explained that when a conductor is placed in the path of a changing magnetic field, an induced current is produced in the conductor through a process of magnetic induction, this induced current in turns produces a magnetic field that opposes the direction of change of the magnetic field producing it. 

The opposite direction of this magnetic field is indicated by the negative sign in Faraday's law of induction;  ε =  - ∂Φ/∂t, ε implies induced electromotive force, ∂Φ is the change in magnetic flux and ∂t means the change in time. Since these two magnetic fields have different charges, they tend to oppose each other and produce a counter rotate motion.

Faraday's law of electromagnetic induction described the induced EMF of a closed circuit system to be equal to the negative rate of change of the magnetic flux. It further explains the interaction of magnetic field with an electric circuit to produce an EMF. A left-hand rule is used to determine the direction of an electromotive force directly from Faraday's law without involving the Lenz's law of action and reaction.

**Ampere-Biot-Savart's law of electromagnetic induced forces**
Biot-Savart's law derived an expression to calculate the magnetic field of a current carrying conductor at a particular point in space. The magnetic field is directly proportional to the product of the current of the conductor material (I), the change in length of the current carrying conductor (dl), and the sine angle of orientation of the conducting material (sinθ) and inversely proportional to the square of the distance from the current coils producing it (r). 
<center>https://cdn.steemitimages.com/DQmbEJ1c8ZW1T654cUh5autgeiUbZ4JDSLxcAceEPZynXRb/image.png</center>

<center>https://cdn.steemitimages.com/DQmV9RZB8ZLdXh5AsyobtM1pTAFj6iws4MzbYPiKd5jjgKQ/image.png
[By Eviatar Bach - Own work, CC0](https://commons.wikimedia.org/w/index.php?curid=16608674)</center>

# References
1. http://geosci.uchicago.edu/~moyer/GEOS24705/Readings/Klempner_Ch1.pdf
2. https://en.wikipedia.org/wiki/Lenz%27s_law
3. https://www.electricaleasy.com/2014/02/AC-generator-alternator-construction-working.html
4. https://en.wikipedia.org/wiki/Alternator
5. https://sciencing.com/differences-between-motors-generators-5398408.html

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