This document discusses phasor analysis of RC, RL, and RLC circuits. For an RC circuit, the voltage across the capacitor lags behind the current by 90 degrees. For an RL circuit, the voltage across the inductor leads the current by 90 degrees. For an RLC circuit, the behavior depends on whether the reactance of the inductor or capacitor is higher. If the inductor reactance is higher, it behaves like an RL circuit. If the capacitor reactance is higher, it behaves like an RC circuit. If the reactances are equal, it behaves like a resistive circuit.

1. Topic : Analysis of Phasor Diagram
Guided By :
Branch : Batch :
Elements Of Electrical Engineering (2110005)

2. Name ENROLLMENT NO.
Abhishek Chokshi 140120109005
Raj Shah
Adnan Vohra
140120109054
140120109063

4. Circuit contain a pure
resistance R ohms
connected in series with
pure capacitor C farads.
It is known as R-C circuit.

5. Voltage across resistance
V=IR.
Voltage across capacitor
V=IC.
Vr remain in same phase.
Vc lag behind current

6. 6
Kirchhoff’s voltage law:
Or;
0 CR VVEV
CR VVE 

7. in such circuits the
voltage across each
of the components
is the same and it
is the currents that
are of interest

8.  Phasor analysis of an RC circuit

11. Circuit contains a pure
resistance R ohms
connected in series with a
pure inductance L henry .
It known as R-L circuit

12.  Phasor analysis of an RL circuit

13. Voltage across resistor
:V=IR.
Voltage across
inductor:V=IL.
Vr is in same phase.
Vl leads by 90’.

14.  From the phasor diagram it is clear that that
the magnitude of the voltage across the
arrangement V is
where
 Z is the magnitude of the impedance, so Z
=|Z|
IZ
XRI
IXIR
VVV
L
L
LR




22
22
22
)()(
22
LXRZ 

15. In this case ,when only
inductor current leads the
voltage by 90’.

16. But when we combine
Resistance and inductance
the phase angle is between
0’ to 90’.

17. Phasor diagram:

19.  Circuit which contains a pure
resistance of R ohms.
 A pure inductor of L henry.
 A pure capacitor of capacitance C
farads.
 It is known as R-L-C series
circuit.

21.  Voltage drop across resistance:Vr=IR in
phase with current I.
 Voltage drop across inductance:VL=IXL
leadin by 90 ‘
 Voltage drop across capacitance:Vc=Ixc
lagging behind by 90’.

22.  Phasor analysis of an RLC circuit

23.  (1)VL >VC that is XL>XC:

24. The phase angle is positive
.
Behave as R-L circuit.
Current lag behind voltage
Power factor is lagging

25. Phase angle is negative.
Behave as a R-C circuit.
Current leads the voltage.
Power factor is leading.

26. Phase angle is zero.
Circuit is purely resistive
circuit.
Current is in phase with
applied voltage.
Power factor is unity.