How Do You Determine Thevenin Resistance in RLC Circuits for DC and AC?

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SUMMARY

To determine the Thevenin resistance in RLC circuits, the approach differs between DC and AC circuits. In DC circuits, the inductor is replaced by a short circuit due to zero reactance, while the capacitor is treated as an open circuit due to infinite reactance. For AC circuits, the reactance of both the inductor and capacitor must be calculated based on the frequency, and neither component is replaced with a short or open circuit. This distinction is crucial for accurate analysis of RLC circuits.

PREREQUISITES
  • Understanding of RLC circuit components (Resistor, Inductor, Capacitor)
  • Knowledge of reactance calculations for inductors and capacitors
  • Familiarity with AC and DC circuit analysis
  • Ability to interpret circuit schematics
NEXT STEPS
  • Study the calculation of reactance for inductors and capacitors in AC circuits
  • Learn about Thevenin's theorem and its application in circuit analysis
  • Explore circuit simulation tools like LTspice for RLC circuit analysis
  • Review examples of RLC circuit schematics to practice identifying Thevenin resistance
USEFUL FOR

Electrical engineering students, circuit designers, and professionals analyzing RLC circuits for both DC and AC applications will benefit from this discussion.

drecklia
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I want to know how to find the R thevenin of an RLC circuit. Do I short the inductor and open the capacitor? or do I remove both capacitor and inductors?
 
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drecklia said:
I want to know how to find the R thevenin of an RLC circuit. Do I short the inductor and open the capacitor? or do I remove both capacitor and inductors?

There's more than one kind of RLC circuit. You should show a schematic.
 
It depends on whether you have a DC circuit or an AC circuit.

1) DC

A) Since the reactance of an inductor is given by:
XL = j*(2 * pi * f * L)
and (f = 0) in a DC circuit, so inductor is replaced by a short circuit. ( An element with zero reactance or resistance)

B) For the capacitor:
Xc = 1 / (j*(2 * pi * f * C))
Substituting zero for f, the answer will be infinity (an open circuit).

2) AC

The value of frequency is substituted in each case and a reactance will be obtained for each element. Neither the inductor nor the capacitor will be replaced with short or open.
 
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