Definition
A phasor straight line, having defi-
nite length and direction, which rep-
resents scale the magnitude and
direction quantity such cur-
rent, voltage impedance. phasor straight line,
having definite length and direction, which represents scale the magni-
tude and direction quantity such current, voltage impedance. circuit the current and voltage
waveforms remain together, starting and finishing the same time. 10. circuit
When resistor only connected a.c. circuit the
current leads the voltage angle 90°.
To find the combined effect two quantities combine their phasors by
adding the beginning the second phasor the end the first.
Z X
Z
Z
Z
Z
2
L
2 2
( )
5 12
25 144
169
13
2 Ω
∴
Ω
Example 2
Calculate the impedance when 48Ω resistor connected series with 55Ω capacitive
reactance.c.
Z X
Z
Z
Z
Z
2
C
2
2 2
( )
55
2304 3025
5329
73
Ω
Ω
∴ 48
Resistance, inductance and capacitance a. When pure capacitor connected a. Phasor
diagrams allow produce model picture the circuit under consid-
eration which helps understand the circuit.
PHASOR DIAGRAMS
Phasor diagrams and a.c.c. circuit the current lags behind
the voltage waveform angle 90°.Alternating current theory and electrical machines
197
Example 1
Calculate the impedance when resistor connected series with 12Ω inductive
reactance. The com-
bined effect the two quantities shown the resultant phasor, which
is measured from the original zero position the end the last phasor. say that the current lags
the voltage 90°. These various effects can be
observed oscilloscope, but the circuit diagram, waveform diagram
and phasor diagram for each circuit are shown Fig. say
that the waveforms are phase.
When pure inductor connected a.c. circuits are inseparable combination.
.2
