BASIC ELECTRICAL ENGINEERING
Basic Laws: Ohm’s law, Kirchhoff’s voltage and current laws, Nodes-Branches
and loops, Series elements and Voltage Division, Parallel elements and Current Division, Star-Delta transformation, Independent sources and Dependent sources, source transformation.
OHM’S LAW
At constant temperature, the current flowing through a conductor is directly
proportional to the potential difference(p.d) in volts across the two ends of the given
conductor and inversely proportional to the resistance (R) in ohms (Ω) between the ends of the same conductor.
I = V/R , V=IR, R=V/R
In all practical problems of electrical calculations, it is assumed that the temperature rise is within limits, so that electrical properties such as insulation and conduction properties of the given material are not destroyed.
KIRCHOFF’S CURRENT AND VOLTAGE LAWS ( KCL and KVL)
KIRCHOFF’S CURRENT LAW :
KCL states that the total current entering a junction is equal to the total current leaving the junction. The algebraic sum of the currents at the junction (node) will be zero.
At node n, (i2+i3+i4) = (i1+i5+i6)
(i1-i2-i3-i4+i5+i6) = 0
KIRCHOFF’S VOLTAGE LAW:
KVL is based on the law of the law of conservation of the energy, states that the algebraic sum of voltage drops in a closed loop is zero.
V = e1+e2+e3
{Flow of currents in loop is assumed -ve from higher potential to lower potential in elements and +ve from lower to higher potential in Sources}
NODES, BRANCHES AND LOOPS:
Network is an interconnection of elements or devices, circuit is a network providing one or more closed paths.
A BRANCH represents a single element such as voltage source or a resistor.
A NODE is the point of connection of two or more branches.
A LOOP is any closed path in a circuit.
A network with ‘b’ branches, ‘l’ loops and ‘n’ nodes should satisfy the theorem of n/w
topology.
b = l + n - 1