In the world of electricity, there are several basic laws of electricity, namely:
- Faraday's Law
- Ampere-Biot-Savart Law
- Lenz's law
- Principles of Electromechanical Energy Conversion
All of the above laws, together with the law of conservation of energy, will explain the basic working principles of a dynamic electric machine.
1. Faraday's Law
Michael Faraday (1791-1867), a genius scientist from England stated that:
1. If a conductor cuts lines of force from a constant magnetic field (flux), the conductor will cause an induced voltage. 2. Changes in magnetic field flux in a conductor circuit will cause an induced voltage in the circuit.
Both of his statements above are the basic laws of electricity which explain the phenomenon of electromagnetic induction and the relationship between flux changes and the induced voltage generated in a circuit, the application of this law is in generators. Figure 1 will explain this phenomenon.
Figure 1. Faraday's Law, Electromagnetic Induction.
2. Ampere-Biot-Savart Law
genius scientists from France, Andre Marie Ampere (1775-1863), Jean Baptista Biot (1774-1862) and Victor Savart (1803-1862) stated that:
"The force will be generated by an electric current flowing in a conductor that is between the magnetic fields"
This is also the opposite of Faraday's law, where Faraday predicts that an induced voltage will arise in a moving conductor and cut across the magnetic field. This law is applied to electric machines, and Figure 2 will explain this phenomenon.
Figure 2. Ampere-Biot-Savart Law, Electromagnetic Induction Force.
3. Lenz's law
In 1835 a scientist of genius who was born in Estonia, Heinrich Lenz (1804-1865) stated that:
"Electromagnetic induced currents and forces will always try to cancel each other out (action and reaction forces)"
For example, if a conductor is given a force to rotate and cut lines of magnetic force, then the conductor will arise an induced voltage (Faraday law). Then if the ends of the conductors are connected to each other, the induced current will flow, and this induced current will produce a force on the conductor (ampere-biot-savart law). What Lenz will reveal is that the force produced is in the opposite direction to the direction of the conductor movement, so that it will cancel each other out.
Lenz's law explains the working principle of dynamic electric machines (rotary electric machines), namely generators and motors.
Figure 3.Lenz's law - force of action and reaction.
4. Electromechanical Energy Conversion
The three basic laws of electricity above occur in the work process of an electric machine and this is the basic principle of energy conversion. Broadly speaking, the electromechanics of a dynamic electric machine is stated:
"All electrical energy and mechanical energy flows into the machine, and only a small portion of the electrical energy and mechanical energy flows out of the machine (is wasted) or is stored in the machine itself, while the wasted energy is in the form of heat"
Whereas the first energy conservation law states that:
"Energy cannot be created, but can change form from one form of energy to another."
The application of the 4 basic working principles of dynamic electric machines and the law of conservation of energy is described as follows:
Figure 4. Principles of Electromechanical Energy Conversion.
A positive sign (+) indicates incoming energy, while a negative sign (-) indicates energy going out. The heat generated from a machine that is processing is always in a negative sign (-).
As for stored energy, a positive sign (+) indicates an increase in stored energy, while a negative sign (-) indicates a decrease in stored energy.
The balance of the energy forms above depends on the efficiency of the engine and the cooling system.
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