DET 101 ELECTRIC CIRCUIT FUNDAMENTAL I Chapter 2

DET 101 ELECTRIC CIRCUIT FUNDAMENTAL I Chapter 2 Part I: Circuit Theorems Dr. Muhammad Solihin Zulkefli Room 11, Block 3, Campus Uni. MAP Pauh Putra

CH 3 PART I: CIRCUIT THEOREMS § Superposition Theorem § Thevenin’s Theorem § Norton’s Theorem § Maximum Power Transfer Theorem

PREVIOUS CHAPTER Series Resistance Current Voltage Parallel

PREVIOUS CHAPTER Series Parallel KVL KCL VDR CDR Law Rule

CH 3 PART I: CIRCUIT THEOREMS § Superposition Theorem § Thevenin’s Theorem § Norton’s Theorem § Maximum Power Transfer Theorem

SUPERPOSITION THEOREM § Some circuits use more than 1 voltage or current source. When multiple sources are used in a circuit, the superposition theorem provides a method for analysis. § The superposition method is a way to determine currents in a circuit with multiple sources by leaving 1 source at a time and replacing the other sources by their internal resistances. § Ideal voltage source: Zero internal resistance § Ideal current source: Infinite internal resistance

SUPERPOSITION THEOREM Example 1:

SUPERPOSITION THEOREM Example 1:

SUPERPOSITION THEOREM Example 1:

SUPERPOSITION THEOREM Example 1:

SUPERPOSITION THEOREM Exercise 1: Find the current through R 2. ANS: I 2 = 50 m. A

SUPERPOSITION THEOREM Exercise 2: Find the current through R 2. ANS: I 2 = 100 m. A

SUPERPOSITION THEOREM Exercise 3: Find the current through R 4 and if Vs= 5 V. ANS: 7 m. A

CH 3 PART I: CIRCUIT THEOREMS § Superposition Theorem § Thevenin’s Theorem § Norton’s Theorem § Maximum Power Transfer Theorem

THEVENIN’S THEOREM § Thevenin’s theorem states that any two-terminal, resistive circuit can be replaced with a simple equivalent circuit when viewed from two output terminals. § The equivalent circuit is:

THEVENIN’S THEOREM § VTH is the open circuit voltage between the two output terminals of a circuit. § RTH is the total resistance appearing between the two output terminals when all sources have been replaced by their internal resistances.

THEVENIN’S THEOREM

THEVENIN’S THEOREM Example 2: Find the Thevenin equivalent circuit between A and B. ANS: VTH = 4. 08 V , RTH = 1410 Ω

THEVENIN’S THEOREM Solution:

THEVENIN’S THEOREM Solution:

THEVENIN’S THEOREM Solution:

THEVENIN’S THEOREM Thevenin equivalency depends on the viewpoint. . !!

THEVENIN’S THEOREM

THEVENIN’S THEOREM

THEVENIN’S THEOREM Exercise 4: a) Determine the Thevenin equivalent circuit viewed from terminals A and C. b) Determine the Thevenin equivalent circuit viewed from terminals B and C. ANS: a) VTH(AC) = 5. 88 V , RTH(AC) = 3. 29 kΩ b) VTH(BC) = 2. 43 V , RTH(BC) = 2. 50 kΩ

CH 3 PART I: CIRCUIT THEOREMS § Superposition Theorem § Thevenin’s Theorem § Norton’s Theorem § Maximum Power Transfer Theorem

NORTON’S THEOREM § Norton’s theorem is a method for simplifying a 2 terminal circuit to an equivalent circuit with only a current source in parallel with a resistor. § Regardless of how complex the original 2 -terminal circuit is, it can always be reduced to this equivalent form.

NORTON’S THEOREM Norton’s Equivalent Current, IN § Norton’s equivalent current (IN) is the short-circuit current between 2 output terminals in a circuit.

NORTON’S THEOREM Norton’s Equivalent Resistance, RN § Norton’s equivalent current (RN) is the total resistance appearing between 2 -output terminals in a given circuit with all sources replaced by their internal resistances.

NORTON’S THEOREM Example 3: Determine IN and RN for the circuit within the area in figure below. ANS: IN = 20. 2 m. A , RN = 123. 5 Ω

NORTON’S THEOREM Solution:

NORTON’S THEOREM Solution:

CH 3 PART I: CIRCUIT THEOREMS § Superposition Theorem § Thevenin’s Theorem § Norton’s Theorem § Maximum Power Transfer Theorem

MAXIMUM POWER TRANSFER § Maximum power transfer is a technique for calculating the maximum value of power that can be delivered to a load, RL. § Maximum power transfer occurs when: RL = RTH (or source resistance, RS) or

MAXIMUM POWER TRANSFER Example 4: The source in circuit below has an internal source resistance of 75 Ω. Determine the load power for each of the following values of load resistance: a) 0 Ω b) 25 Ω c) 50 Ω d) 75 Ω e) 100 Ω f) 125 Ω

MAXIMUM POWER TRANSFER Solution: Use Ohm’s law find the load power, PL. a) For RL = 0 Ω : b) For RL = 25 Ω : and power formula to

MAXIMUM POWER TRANSFER Solution: c) For RL = 50 Ω : d) For RL = 75 Ω :

MAXIMUM POWER TRANSFER Solution: e) For RL = 100 Ω : f) For RL = 125 Ω :

MAXIMUM POWER TRANSFER