5
A series circuit and phasor diagram.5 and 10.6 show the voltage phasors, but we
know that IR, IXL, IXC and IZ, and therefore the pha-
sor diagrams (a) and (b) Fig.6, is
lagging the current some angle φ. circuit. 10. 10.6
A series circuit and phasor diagram. From Fig.
L
VL VR
R
I
VT
I
VL VT
VR
FIGURE 10. The phasor addition these
voltages equal the total voltage which, can seen Fig.7 must equal.
.
The impedance triangle
We have now established the general shape the phasor diagram for a
series a. The phasor addition these two voltages gives the mag-
nitude and direction VT, which leads the current some angle φ.
In circuit containing resistor and capacitor connected series as
shown Fig.6, the current will flow through the resistor and capaci-
tor causing voltage drops and VC. 10. The voltage will phase with
the current and will lag the current 90°. 10.7(c). 10. Figures 10.Alternating current theory and electrical machines
199
scale and phase with the current and drawn scale and leading the
current 90°.c.7(b), by
the theorem Pythagoras, have:
( )
IZ IX
2 X
2
If now divide throughout I2
we have:
Z X
Z X
2 2
2 2
or
Ω
The phasor diagram can simplified the impedance triangle given in
Fig.
C
VC VR
R
I
I
VT VT
VR
FIGURE 10
