Download 슬라이드 1

9th Group : 최유경
최인기
윤철한
한성연
하민욱
1th 최인기
2nd 윤철한
3rd 하민욱
4th 최유경
5th 한성연
Any circuit with sources and resistors can be replaced
by an equivalent circuit containing a single voltage
source and a single resistor.
1.Break the part A-B
There is no current through R1 because above
calculations are done in an open circuit
condition between A and B. Therefore no
voltage drop along this part.
2.Calculate voltage
between A and B
3.Reomove all the
sources and calculate Req
The equivalent circuit is a voltage source with voltage
Vth in series with a resistance Req.
Any Thevenin equivalent circuit can be replaced
by a current source in parallel with a resistor.
1. Connect the part A-B
Current starts to flow
between A and B.
2.Calculate the current
3.Reomove all the sources
and calculate Req
the equivalent
circuit is a 3.75 mA
current source in parallel
with a 2 kΩ resistor.
Loading Effect
Smaller the resistance Rs is, more voltage
is transferred from a source to a load
Loading Effect
Bigger the resistance Rs is, more current
is transferred from a source to a load
Power Limiting
In Thevenin Equivalent Circuit
Rs
Vs
RL
RL
VL
IL
1Ω
1V
1A
10Ω
10V
1A
1kΩ
10V
10mA
100kΩ
10V
100µA
Maximun Power Consumption : 10W
Rated Voltage : 10V => Rated Maximun Current : 1A
As a load resistance is 1Ω, voltage of the above circuit
is supposed to be 10V and current 10A and power
consumption 100W. However, the power consumption is
out of the maximum level then this circuit cannot work
properly. It is called an overload. Therefore, to maintain the
maximum power consumption, the current is supposed to
be 1A and the voltage 1V in accordance with Ohm’s law.
12
10
10
1
V
8
0.1
6
0.01
I
V(V)
I(A)
4
0.001
2
0.0001
0
1E-05
1Ω
10Ω
1kΩ
100kΩ
In accordance with the load resistance,
voltage and current change. As the resistance
is smaller than 10 Ω, the circuit is on the
overload.
Power Limiting
In Norton Equivalent Circuit
Is
Rs
RL
RL
IL
VL
1Ω
10mA
0.01V
100Ω
10mA
1V
10kΩ
10mA
100V
100kΩ
1mA
100V
Maximun Power Consumption : 1W
Rated Current : 10mA => Rated Maximun Voltage : 100V
As a load resistance is 100kΩ, current of the above circuit
is supposed to be 10mA and voltage 1000V and power
consumption 10W. However, the power consumption is out of
the maximum level then this circuit cannot work properly. It is
called an overload. Therefore, to maintain the maximum
power consumption, the voltage is supposed to be 100V and
the current 1mA in accordance with Ohm’s law.
I
12
1000
10
100
8
10
6
1
V
I(mA)
V(V)
4
0.1
2
0.01
0
0.001
1Ω
100Ω
10kΩ
100kΩ
In accordance with the load resistance,
voltage and current change. As the resistance is
bigger than 10kΩ, the circuit is on the overload.
 The rated voltage in Korea is 220V.
 We nowadays use fixed voltage in parallel
with electric appliances.
 Therefore, overload is caused by excessive
current.
Overload might happen if we
put many plugs of electric
appliances in the only one outlet.
 Each of electric appliances has individual
power consumption. For instance, we have
an american electric appliance(rated voltage
is 120V in America) that power consumption
is 120W. It allows current to flow up to 1A
and its resistance is 120Ω.
Thus, if we plug it in korea, the current 1.9A
flows through the appliance then the
appliance is damaged due to overload.