Capacitor Load

1
Capacitor Load
The capacitive reactance of a capacitor
Generalized Ohms law
Notice Ic and VC are amplitudes
ICE
2
Inductive Load
The Inductive reactance of a inductive
Generalized Ohms law
Notice IL and VL are amplitudes
ELI
3
The series RLC circuit
1. Same current through R, L, C
Same frequency as in the source
2. Consider VR, VC, VL
4
The series RLC circuit Continuous
Values at t.
This relation has to be maintained as phosors are
rotating

• General rules
• KVL and KCL still hold, but values at the same t
  have to be used, i.e. vertical components in
  phasor diagram.
• Vectors operation for Amplitude

5
The series RLC circuit Continuous
IZ
IR
I(XL-XC)
Z is the impedance of the circuit
6
Examples
33-43P. A coil of inductance 88 mH and unknown
resistance and a 0.94 mF are connected in series
with an alternating emf of frequency 930 Hz. If
the phase constant between the applied voltage
and current is 75?, what is the resistance of the
coil.
f930 Hz wd2pf
7
RLC Resonance
XLgtXC inductive loading
XLXC Resonance
XCgtXL Capacitive loading
8
RLC Resonance Cont
9
Conditions at Resonance

• I is a maximum

• Z is at minimum ZR Z is purely resistive

• XLXC inductive reactance cancels capacitive
  reactance net reactance is zero

• The phase angle is zero the current is
  perfectly in phase with applied emf the tangent
  of the phase angle is zero.

• The driven frequency is identical to the
  natural frequency.

• The power factor is unity