Assignment Polyphase
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Transcript of Assignment Polyphase
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POLYPHASE CIRCUIT ANALYSIS [BEF23803]
SECTION 1ASSIGNMENT 1
LECTURERS NAME: DR. ERWAN BIN SULAIMAN
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GROUP MEMBERS NAME:
SHARINI A/P P.JANASEKARAN
[CE130108]
NURUL HANIS BINTI MUHAMAD SOBRI
[CE130165]
AZLIN HAZWANI BINTI ROSLEE
[CE130125]
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DISCUSS THE DIRECTION OF
POWER FLOW IN CONVENTIONAL
POWER SYSTEM CIRCUIT
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Direction of Power Flow
It is assumed that a specific load is consuming power. If however we are
generating power, then the direction of the current flows is reversed. But
because the current is alternating, the direction is reversing anyway, 50 or
60 times each second. We need a reference to compare the current
direction against. Fortunately, we have that in the form of the voltage.
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In figure 1, the voltage and current waves both rose and fell together. When thevoltage was positive (above the x axis) then the current too was positive, and when the
voltage was negative (below the x axis) then the current too was negative.
Power is equal to the product of the voltage and current and so the power was always
positiveall of the power curve is above the x axis.
Figure 1Voltage, current, power graph of a resistive load
http://openenergymonitor.org/emon/sites/default/files/resistive2.jpghttp://openenergymonitor.org/emon/sites/default/files/resistive2.jpg -
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If the house is generating power, the direction of the current is reversed compared to
how it was before. Now, when the voltage is positive (above the x axis) then the current
is negative (below the x axis), and when the voltage is negative then the current is
positive. The power always negativeall of the power curve is below the x axis.
The sign of the power therefore indicates whether power is being consumed or
generated.
Figure 2Voltage, current, power graph when generating
http://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.pnghttp://openenergymonitor.org/emon/sites/default/files/revpower.png -
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GIVE THE DEFINITION OF
MAXIMUM AVERAGE POWERTRANSFER
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Definition of Max. Average
In the maximum average power transfer theoremstates that the maximum external power from a sourcewith finite internal resistance. The internal resistanceof the load must be equal the resistance of the source
as viewed from its output terminal.
To solved the problem of maximizing the powerdelivered by a power-supplying resistive network to aload RL. Representing the circuit by its Thevenin
equivalent with proved that the maximum powerwould be delivered to the load if the load resistance isequal to the Thevenin RL = RTH.
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EXPLAIN CLEARLY HOW TO FIND
THE MAXIMUM POWERTRANSFER AT THE LOAD USING
THEVENIN EQUIVALENT CIRCUIT
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Find the Max. Power Transfer
Finding the maximum average power which can be transferred from a linear circuit to a loadconnected.
Circuit with a load Thevenin Equivalent circuit
The circuit at the right side represents the circuit to the left of the load by its Thevenin
equivalent.
LoadZLrepresents any element that is absorbing the power generated by the circuit.
Find the Maximum Average Power that will be absorbed by loadZLfrom the circuit to
which it is connected. The entire circuit is replaced by the thevenin equivalent except for
the load.
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EXPLAIN AN EXAMPLE TO SOLVE A
PROBLEM OF MAXIMUM POWER
TRANSFER IN RLC CIRCUIT
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Example of Problem in RLC Circuit
EXAMPLE 1:
Calculate the resistive load needed for maximum power transfer and the
maximum average power.
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EXAMPLE 1:
Calculate the resistive load needed for maximum power transfer and the
maximum average power.
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EXPLAIN THE CONDITION OF
MAXIMUM AVERAGE POWER FOR
RESISTIVE LOAD. SOLVE AN
EXAMPLEFOR THE ABOVE CONDITION
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Condition for Resistive Load
When the load is purely resistive, the condition for
maximum power transfer is:
Now the maximum power can not be obtained from the
Pmaxformula.
Maximum power can only be calculated by finding the
power of RL when XL=0.
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Example of Problem
Determine the load impedance, ZL that maximizes the average power drawn from the
circuit. What is the maximum average power?
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