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Thevenin's theorem for ac network
- 1. CIRCUIT THEORY THEVENIN’S THEOREM FOR AC NETWORK Saturday, August 10, 2019 1syed hasan saeed SYED HASAN SAEED
- 2. THEVENIN’S THEOREM REFERENCE BOOKS • Introductory Circuit Analysis, Robert L. Boylested, Pearson Education, Prentice Hall. • Networks And Systems, Ashfaq Husain, Khanna Book Publishing Co (P) Ltd. Delhi. • Networks And Systems, A Sudhakr, Shyammohan S Palli, Tata McGraw Hill, New Delhi. • Network Analysis, M.E. Van Valkenburg, PHI Learning Private limited, New Delhi. • Circuit Analysis Principle and Applications, Allan H. Robbins &Wilhelm C. Miller, DELMAR CENGAGE Learning, Indian Reprint. Saturday, August 10, 2019 syed hasan saeed 2
- 3. THEVENIN’S THEOREM STATEMENT: In any linear, active, bilateral AC network the load across its terminal a-b can be replaced by a simple equivalent circuit having single AC voltage source (Vth) in series with a single impedance (Zth). Where (Vth) is the known as Thevenin’s equivalent voltage across the terminal a-b. (Zth) is the Thevenin’s equivalent impedance viewed back into the network from terminal a-b. Note: independent voltage sources are short circuited and independent current sources are open circuited. Dependent sources will remain in the circuit for the calculation of Norton’s equivalent resistance. Saturday, August 10, 2019 syed hasan saeed 3
- 4. THEVENIN’S THEOREM Saturday, August 10, 2019 syed hasan saeed 4 Procedure For Converting Any Circuit Into Thevenin’s Equivalent Circuit And Its Calculations: Step 1: Identify and temporarily remove the impedance (load impedance ZL) through which the current is required. Suppose these terminals are label as a-b. Therefore a-b is the open circuited. Step 2: Find the voltage across the terminal a-b by applying KCL, KVL, Ohm’s law or Superposition principle. This voltage is the open circuit voltage (Voc) and it is known as Thevenin’s equivalent voltage (Vth). Step 3: Set all voltage Sources short circuited and Current Sources open circuited Step 4: Calculate the impedance as “seen” through the terminals a-b into the network. This impedance is known as Thevenin’s equivalent impedance (Zth). Step 5: Replace the entire network by Thevenin’s equivalent voltage (Vth) in series with Thevenin’s equivalent impedance (Zth). Step 6: Reconnect the previously removed impedance (load impedance ZL) to this circuit.
- 5. Step 7: Calculate the Current through load resistance Saturday, August 10, 2019 syed hasan saeed 5 THEVENIN’S THEOREM A.C. NETWORK Vth Zth Linear, Active, Bilateral Network a b b a IL IL Thevenin’s Equivalent Network Fig. (1a) Fig. (1b) ZL ZL ZL
- 6. THEVENIN’S THEOREM A.C. NETWORK EXAMPLE: Find the Thevenin’s Equivalent circuit of the network viewed from terminal a-b. Saturday, August 10, 2019 syed hasan saeed 6 V010 0 8 ohm 6 ohm 2 ohm a bFig.2a STEP 1: Remove 2 ohm resistor, set the voltage source to zero i.e short circuit and redraw the circuit as shown in fig.2b STEP 2: Calculation of Zth parallelinareZandZ ohmj6-jXZ ohmj8jXZ 21 C2 L1 8 ohm 6 ohm b a Fig.2b 1Z 2Z
- 7. THEVENIN’S THEOREM A.C. NETWORK Saturday, August 10, 2019 syed hasan saeed 7 0 0 0 th 0 00 21 21 th 9024 902 048 Z 902 )906)(90(8 ZZ ZZ z STEP 3: Calculation of Thevenin’s Equivalent voltage Vth 8 ohm 6 ohm a b V010 0 Vth Apply KVL in mesh (1) I V18030V )90-(-j6)(5IZV A905 902 010 I j2I010 0j6Ij8I-010 0 th 0 2th 0 0 0 0 0 Fig. 3 -j6 ohm j8 ohm
- 8. THEVENIN’S THEOREM A.C. NETWORK STPE 4: Draw the Thevenin’s Equivalent Circuit Saturday, August 10, 2019 syed hasan saeed 8 Vth Zth V18030 0 0 9024 a b Fig. 4
- 9. Saturday, August 10, 2019 syed hasan saeed 9 THANK YOU hasansaeedcontrol@gmail.com shasansaeed@yolasite.com hasansaeed872726549.wordpress.com saeed.moodlecloud.com syedhasansaeed.gnomio.com