Wednesday 1 May 2019

Terminologies of an Electrical Network

Terminologies of an electrical network

Electrical network: Any arrangement of electrical energy sources and circuit elements is called an electrical network.
Electrical energy sources can be batteries and generators. Circuit elements are resistance (R), inductance (L), and capacitance (C).
Figure 1: Electrical Network or Electrical Circuit
Electrical Circuit:  It is a closed path followed by an electric current. All electrical circuits are electrical networks. 

Read about the differences between two types of the electrical circuit: Series and Parallel Circuit.

Source: It is the device that supplies electrical energy. Example: Battery, Generator.

Load: It is the device that utilizes electrical energy. Example: Lamp, Motor, Heater.

Network elements: It is any circuit element with two terminals that can be connected to other circuit elements. Example: Resistors R1, R2, R3 in Figure 1.

Node: It is a junction where two or more circuit elements are connected together. Example: Points 1,2,3,4,5,6 in Figure 1.

Minor node: Point at which only two elements are connected together. Example: Point 1 in Figure 1.

Major node: Point at which three or more elements are connected together. Example: Points 2,5 in Figure 1.
In circuit analysis, the term node implies only the major node.

Branch: It is the part of a circuit that lies between two junction points. Example: 1-2, 2-5, 1-6 in Figure 1.

Loop: It is any closed path of a circuit. Example: 1-2-3-4-5-6, 1-2-5-6, 2-3-4-5 in Figure 1.

Mesh: It is the most elementary form of a loop. A mesh cannot be further divided into other loops. Example: 1-2-5-6, 2-3-4-5 in Figure 1. The loop 1-2-3-4-5-6 is not a mesh because it encloses two loops (1-2-5-6, 2-3-4-5).

Other Definitions

Unit of charge: coulomb
1 coulomb = charge on 6.28 * 10^18 electrons
A body has a positive charge of 1 coulomb means that it has a deficit of 628*10^26 electrons.
The symbol is  Q or q.

Electric Potential: The ability of a charged body to do work is called electric potential.
where, Work done is in Joules, the charge is in coulombs, the electric potential is in volts.
A body is said to have an electric potential of 1V if 1J of work is done to give it a charge of 1C.

Electric current: The flow of free electrons in a metal is called electrical current.
The strength of the electric current is the rate of flow of electrons (ie.,) charge flowing per second.
The charge is in coulomb, time is in seconds, the current is in ampere.
One ampere of current is said to flow through a wire if, at any section, one coulomb of charge flows in a second.

Potential Difference: The potential difference is the difference in the potentials of two charged bodies. Its unit is volt.
The potential difference between two points is 1 V if 1 J of work is done in transferring 1 C of charge from one point to another.

Electromotive force: The device that maintains a potential difference between two points is said to develop electromotive force.
The potential difference causes current flow while an emf maintains the potential difference.
EMF is the energy supplied to the charge by an active device such as a battery.

Electrical Power: It is the rate at which work is done in an electric circuit.
The work done in an electrical circuit is calculated by the movement of electrons in the circuit. The movement of electrons indicates the flow of current. The voltage has to be applied for the current to flow ie., for the movement of electrons.
Work done in an electrical circuit  = V * Q         
                                                               [Q = I *t]
                                                 = V * I * t
Therefore, Electrical Power, P = V * I  (watts)
                               Also, P = I2R = V2/R      [V= IR]

Electrical Energy: It is the total work done in an electrical circuit.
Electrical Energy = Potential Difference * Total Charge Flow
                                             = V * Q                       [Q = I *t]
                                             = V * I * t
                          = P * t (watt - second).
Electrical Energy is the product of electrical power and time for which the current flows in the circuit.
1 kWhr of Electrical Energy = 1 unit
                             1 kWhr = 10^3 * 60* 60 W s.





1 comment:

  1. A useful article for beginner electrical engineering students! Additionally, it is always exciting going back to the basics for experienced guys and refreshing your knowledge on some of these fundamental topics in electrical.

    ReplyDelete

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