Name: finding voltage and impedance in circuit a
Uploaded: 2025-05-22T09:06:14.000Z
Duration: 1 min 18 s
Channel: JoVE

מערכת חלוקת החשמל הביתית הכוללת קווי חלוקה ושנאים, יכולה להיחשב לרשת המקור.
בתוך הבית, מכשירי חשמל שונים יכולים להיות מיוצגים כעכבות עומס.
משפט תבנין מפשט את מערכת ההתפלגות המרוכבת הזו למעגל מקביל לתבנין.
מציאת המעגל המקביל של תבנין דורשת ידע בשני פרמטרים: מתח תבנין ועכבת תבנין.
כדי להבין את תהליך קביעתם, שקול מעגל RLC פשוט המחובר למקור מתח.
כדי לחשב את עכבת תבנין, החלף את מקור המתח בקצר חשמלי וקבע את העכבה המקבילה של המעגל.
מתח תבנין שווה למתח המעגל הפתוח, שווה ערך לירידת המתח על פני הענף המקביל של המעגל.
בתחילה, הזרם הזורם דרך הרשת הסגורה של המעגל מחושב. לאחר מכן, באמצעות חוק אוהם, נקבעת ירידת המתח על פני הענף המקביל, מה שנותן את מתח תבנין.
אם למעגל יש מקורות הפועלים בתדרים שונים, יש לקבוע בנפרד את המעגל המקביל של תבנין ואת עכבות הקבלים והמשרן עבור כל תדר.

מעגלים מקבילים של תבנין

Th&#233venin Equivalent Circuits

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מערכת חלוקת החשמל הביתית, הכוללת קווי חלוקה ושנאים, משמשת כרשת הראשית. מכשירי חשמל בתוך משק בית יכולים להיות מיוצגים כעכבת עומס. כדי לפשט את מערכת ההפצה המורכבת הזו, ניתן ליישם את המשפט של תבנין כדי ליצור מעגל שווה ערך של תבנין. אם מעגל AC מחולק לשני חלקים (מעגל A ומעגל B), מחובר על ידי זוג מסופים בודד כפי שמוצג בFigure 1.

<img alt="Figure1" src="/files/ftp_upload/15113/15113_PT_Figure_1.svg" style="text-align: center; height: 140px;">
Figure 1: מעגל מחולק לשני חלקים
<img alt="Figure2" src="/files/ftp_upload/15113/15113_PT_Figure_2.svg" style="text-align: center; height: 150px;">
Figure 2: מעגל A הוחלף במעגל תבנין המקביל שלו

החלפת מעגל A במעגל המקביל שלו תבנין (מקור מתח בסדרה עם עכבה) אינה משנה את הזרם או המתח של אלמנט כלשהו במעגל B (מוצג בFigure 2). ערכי הזרמים והמתחים של כל רכיבי המעגל במעגל B יהיו זהים ללא קשר אם מעגל B מחובר למעגל A או המקבילה שלו תבנין. נדרשים שני פרמטרים כדי למצוא את המעגל המקביל של תבנין: מתח תבנין ועכבת תבנין. Figure 3 מציג מעגל פתוח המחובר על פני המסופים של מעגל A כדי לקבוע את מתח המעגל הפתוח Voc, בעוד שFigure 4 מציין שעכבת תבנין Zt היא העכבה המקבילה של מעגל A*. 

<img alt="Figure3" src="/files/ftp_upload/15113/15113_PT_Figure_3.svg" style="text-align: center; height: 96px;">
Figure 3: מעגל שווה ערך של תבנין עם Voc. <img alt="Figure4" src="/files/ftp_upload/15113/15113_PT_Figure_4.svg" style="text-align: center; height: 96px;">

Figure 4: מעגל שווה ערך של תבנין המציג את Zt. מעגל A* נוצר ממעגל A על ידי החלפת כל מקורות המתח העצמאיים במעגלים קצרים וכל מקורות הזרם העצמאיים במעגלים פתוחים. באופן כללי, ניתן לקבוע את עכבת תבנין Zt על ידי החלפת עכבות סדרתיות או מקבילות בעכבות שוות שוב ושוב.</div>

מערכת חלוקת החשמל הביתית הכוללת קווי חלוקה ושנאים, יכולה להיחשב לרשת המקור.
בתוך הבית, ...

Education

JoVE Core

Electrical Engineering

הנדסה חשמלית

Unit 1

יחידה 1

AC Circuit Analysis

ניתוח מעגלי זרם חילופין (AC)

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

finding voltage and impedance in circuit a

The household power distribution system can be simplified with Thevenin's theorem. In this system, distribution lines and transformers form the main network. Electrical appliances can be treated as load impedance, which makes the circuit easier to analyze.

An AC circuit can be split into two parts, circuit A and circuit B, with a single pair of terminals between them. Circuit A can then be replaced by its Thevenin equivalent circuit. That equivalent has a voltage source in series with an impedance.

Replacing circuit A with its Thevenin equivalent does not change the current or voltage of any element in circuit B. The values in circuit B stay the same whether it is connected to the original circuit A or to the Thevenin equivalent. This is why the method is useful for studying connected circuits.

Two values are needed to build the Thevenin equivalent circuit. The first is the Thevenin voltage, which is found from the open-circuit voltage across the terminals of circuit A. The second is the Thevenin impedance, Zt, which is the equivalent impedance of circuit A*.

To form circuit A*, all independent voltage sources are replaced with short circuits. All independent current sources are replaced with open circuits. Then series or parallel impedances can be combined repeatedly to find Zt.

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Learn how Thevenin's theorem simplifies household AC circuits by using open-circuit voltage and equivalent impedance to model circuit A.

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JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

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Finding Voltage and Impedance in Circuit A

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