basic of Electrical Circuit and Networks.pptx

electric circuit and network

1. Electrical Circuit and Networks Sub Code-2420301

2. Course Outcomes (COs): There are three learning domains in classroom/ laboratory/ workshop/ field/ industry. 1.Cognitive 2. Psychomotor and 3. Affective

3. Domains of Learning Cognitive Domain- This domain involves mental skills and the development of intellectual abilities. It ranges from basic recall of facts to complex evaluation and creation. Psychomotor Domain: This domain focuses on physical skills and coordination. Affective Domain: This domain deals with feelings, emotions, values, appreciation, and attitudes.

4. Unit Unit-1.0 Basics of Electrical Circuits Unit-2.0 N etwork Theorems: Unit-3.0 Single Phase AC Circuits: Unit-4.0 Resonance and Two Port Network: Unit-5.0 Three phase AC circuits

5. After completion of the course, the students will be able to- CO-1 Apply basic laws and analysis techniques to simplify the electrical circuits. CO-2 Apply network theorems principles to solve the electrical circuit problems CO-3 Measure electrical quantities in single phase AC circuits. CO-4 Ascertain the resonance condition in a series and parallel RLC circuit and measure 2 port network parameters. CO-5 Measure power and power factor in three phase AC circuits.

6. Term Work and Self Learning: S2420301 a. Assignments b. Micro Projects: c. Other Activities: Seminar Topics Visits: Visit nearby industry/supplier to collect information about the working of phase sequence indicator available in market. Self-Learning Topics

7. Active Elements Active elements are components that can supply energy (power) to a circuit. They are capable of amplifying signals and/or controlling the flow of electrons. Examples: Voltage source Current source Transistors (BJT, MOSFET) Operational Amplifiers (Op-Amps) Integrated Circuits (ICs)

8. Passive Elements Passive elements are components that consume energy (but do not generate or amplify it). They store or dissipate energy. Examples: Resistors (R) Capacitors (C) Inductors (L) Transformers Diodes (Note: Diodes are nonlinear but generally considered passive unless used in certain active circuits)

9. Bilateral and Unilateral Elements A bilateral Elements allow current to flow in both directions and exhibits the same behavior and same impedance in either direction of current flow Examples: Resistor Capacitor Inductor Transmission line A unilateral Elements allow current to flow mainly in one direction and behaves differently in the opposite direction. Hence, they offer different impedances in both directions. Examples: Diode Transistor SCR (Silicon Controlled Rectifier) LED (Light Emitting Diode)

10. Linear element A linear element is an electrical component in which the relationship between voltage (V) and current (I) is a linear function, i.e., it forms a straight-line graph when plotted. A linear element is one in which the electrical parameter (such as resistance, inductance, or capacitance) remains constant, and the voltage-current relationship is linear Obey Ohm’s Law It follow principle of superposition , . Homogeneity: f(k x)=k f(x) Additivity: f(x+y)=f(x)+f(y) Examples - Resistor (R), Capacitor (C), Inductor (L)

11. Non-Linear element A non-linear element is an electrical component in which the relationship between voltage and current is not linear — that is, the V-I curve is not a straight line. The current does not change proportionally with applied voltage. The resistance (or impedance) of the element varies with voltage, current, time, or other conditions such as temperature or frequency . Ohm’s Law is Not Obeyed Superposition Principle Does Not Hold Examples - Diode, Transistor, SCR, Thermistor, Varistor

12. Mesh analysis is based on: A) Kirchhoff's Current Law (KCL) B) Ohm’s Law C) Kirchhoff's Voltage Law (KVL) D) Both KVL and KCL Nodal analysis is based on: A) Kirchhoff's Voltage Law (KVL) B) Kirchhoff's Current Law (KCL) C) Ohm's Law D) Norton’s Theorem In mesh analysis, the number of equations needed is equal to: A)Number of nodes B) Number of meshes (independent loops) C) Number of branches D) Number of sources What is a supernode in nodal analysis? A) A node connected to ground B) A combination of two non-reference nodes connected by a voltage source C) A node where more than three components meet D) A node with the highest voltage In nodal analysis, voltage sources between two non-reference nodes form a: A) Simple node B) Floating node C) Super node D) Dead node The basic requirement for applying mesh analysis is: A) Circuit should be planar B) Circuit should be non-planar C) Circuit must contain only current sources D) Circuit must be in AC A ‘ supermesh ’ is formed when: A) Two meshes are combined B) A current source lies between two meshes C) A voltage source lies in a mesh D) All meshes are connected in parallel What is the minimum number of node voltages required to analyze a circuit with 5 nodes (1 reference)? A) 5 B) 4 C) 3 D) 1

13. An independent source is a source of voltage or current that does not depend on any other element in the circuit. It provides a fixed value. Exaples-12V, 10A

14. Dependent source/Controlled Source A dependent source is a source whose voltage or current depends on some other voltage or current in the same circuit. It is not fixed — it changes according to another quantity elsewhere in the network. Type VCVS – Voltage Controlled Voltage Source VCCS – Voltage Controlled Current Source CCVS – Current Controlled Voltage Source CCCS – Current Controlled Current Source

15. Lumped Parameters An electrical element that is assumed to be concentrated in one place or located in a smaller space in the circuit is said to be known as a lumped element. Lumped elements can be physically separated from the circuit for analysis purposes. A resistor, inductor, capacitor, diode, etc are examples of lumped elements.

16. Distributed Parameters An electrical element that is assumed to be distributed across the entire length of the circuit is called a distributed element. Unlike lumped elements, distributed elements are not concentrated in a single place. Distributed elements cannot be separated from the circuit since they are distributed everywhere in the circuit. Transmission Line is an example of distributed network

17. Transient state & Steady state

18. Transient state & Steady state The transient state is the initial response of a system immediately after a sudden change (like switching ON a voltage source), during which voltages and currents rapidly vary before reaching stability. Shows oscillations, overshoots, undershoots, or sudden spikes. When a switch is turned ON in an RLC circuit, the current rises gradually, not instantly — this period is the transient response . The steady state is the condition when all the transients have died out, and the system's response becomes stable, either constant (DC) or repetitive/predictable (AC) over time. Voltages and currents settle to final values. In a DC circuit with a resistor and capacitor, once the capacitor is fully charged, current stops changing — this is the steady state .

19. Initial Value and Final Value The initial value is the value of voltage or current just before or just after a switching event (typically at t = 0⁺ or t = 0⁻). It tells us the starting condition of the circuit immediately after a change (e.g., switching ON a source). For example: In a capacitor: Vc (0+)= Vc (0−) (capacitor voltage cannot change instantly) In an inductor: IL(0+)=IL(0−) (inductor current cannot change instantly) The final value is the value of voltage or current at steady state, i.e., after all transient effects have died out (t → ∞). It tells us the long-term behavior of the circuit. For example: A capacitor connected to DC will fully charge, and its voltage = supply voltage. An inductor connected to DC becomes a short circuit (0 V across it).

20. RC Charging Circuit 

21. RC Discharging Circuit 

22. Maximum Power Transfer Theorem Maximum power transfer theorem  states that the DC voltage source will deliver maximum power to the variable load resistor only when the load resistance is equal to the source resistance. Similarly,  Maximum power transfer theorem  states that the AC voltage source will deliver maximum power to the variable complex load only when the load impedance is equal to the complex conjugate of source impedance.

23. Equation-1

24. Condition for Maximum Power Transfer

25. The value of Maximum Power Transfer

26. Efficiency of Maximum Power Transfer

27. MCQ Q1. The Maximum Power Transfer Theorem is applicable to a) DC only b) AC only c) Both AC and DC d) Neither AC nor DC Q4. At maximum power transfer condition, the efficiency is a) 100% b) 75% c) 50% d) Depends on source Q5. The Maximum Power Transfer Theorem is most commonly used in a) Power transmission lines b) Electronic communication circuits c) Domestic wiring d) Transformers Q2. For maximum power transfer in a DC circuit , the load resistance RLR_LRL​ must be a) Equal to source voltage b) Equal to Thevenin resistance c) Greater than Thevenin resistance d) Less than Thevenin resistance

28. Circuit Type Phase Relation Average Power Power Factor Nature of Power Pure R V and I in phase 1 Real power (dissipated as heat) Pure L I lags V by 90° Reactive power (stored & returned) Inductor does not consume real power ; it only stores energy in the magnetic field during one half cycle and returns it in the next half cycle. Pure C I leads V by 90° Reactive power (stored & returned) Capacitor does not consume real power ; it stores energy in the electric field during one half cycle and returns it in the next. Circuit Type Phase Relation Average Power Power Factor Nature of Power Pure R V and I in phase 1 Real power (dissipated as heat) Pure L I lags V by 90° Reactive power (stored & returned) Inductor does not consume real power ; it only stores energy in the magnetic field during one half cycle and returns it in the next half cycle. Pure C I leads V by 90° Reactive power (stored & returned) Capacitor does not consume real power ; it stores energy in the electric field during one half cycle and returns it in the next.

29. True/False In a purely resistive AC circuit, current and voltage are in phase. In a purely inductive AC circuit, the average power consumed is zero. In a purely capacitive AC circuit, current lags voltage by . The power factor of a purely resistive circuit is 1. Pure inductors and capacitors do not consume any real (active) power.  

30. MCQ The power factor of a purely inductive or capacitive circuit is: (a) Unity (b) Zero (c) 0.5 (d) Depends on frequency In a purely resistive AC circuit, the average power consumed is: (a) Zero (b) c) with d) e) Both (b) and (c)   The average power consumed in a purely inductive AC circuit is: (a) (b) Zero (c) ( d) Both (b) and (c) Which of the following is true? (a) Pure resistance consumes real power only. (b) Pure inductance consumes no real power. (c) Pure capacitance consumes no real power. (d) All of the above.  

31. Generation of 3 Phase Voltage

32. When three identical coils are placed 120° apart in space and rotated in a uniform magnetic field with angular velocity (ω rad/sec), according to the principle of electromagnetic induction, three equal voltages of the same frequency but displaced in phase by 120° are induced. These voltages together form a balanced three-phase system, which is widely used in power generation, transmission, and distribution.

33. Phase Sequence The phase sequence is the order in which the three-phase voltages (or currents) reach their maximum positive value. It indicates the rotation order of the three voltages or currents in a 3-phase system. For example, if the sequence is R → Y → B, then the R-phase voltage reaches its peak first, followed by Y, then B. This sequence is called the positive or normal phase sequence (R-Y-B). The reverse order R → B → Y is called the negative phase

34. Types of 3-Phase Connections: Star (Y) Connection Delta ( Δ) Connection

35. Star (Y) Connection: One end of all three coils is connected to a common neutral point (N). The other ends are connected to the line terminals (R, Y, B). Used in distribution systems Relationship: V L = √3V P I L = I P Delta (A) Connection: The end of each coil is connected to the start of the next coil, forming a closed loop (triangle). No neutral point. Used in transmission and motors. Relationship: V L = V P I L = √3I P