function of an RL circuit

Thread Starter

falade47

Joined Jan 24, 2017
178
#newtoelectronics..I opened my faulty vacuum cleaner and found a RL circuit there..an inductor after the power line(220vac) then a capacitor then another inductor with a couple of windings then to a switch then to the motor. would like to know the function of the RL circuit..
 

Papabravo

Joined Feb 24, 2006
22,082
#newtoelectronics..I opened my faulty vacuum cleaner and found a RL circuit there..an inductor after the power line(220vac) then a capacitor then another inductor with a couple of windings then to a switch then to the motor. would like to know the function of the RL circuit..
You mentioned two inductors and a capacitor. An RL circuit by definition requires a resistor. What gives?
 

Papabravo

Joined Feb 24, 2006
22,082
It was a misquote..it was purely reactive components just the capacitor and inductor..
OK. Without seeing a schematic, I cannot be absolutely sure, but it sounds like a line filter that is designed to pass low frequency AC and attenuate high frequency AC.
The impedance of an inductor increases linearly with frequency.

\(X_L\;=\;2\pi fL\)

The capacitor will block low frequency AC and look like a short to high frequency AC
The impedance of a capacitor decreases asymptotically to 0 with increasing frequency.

\(X_C\;=\;\frac{1}{2\pi fC}\;\text, and\)
\(\lim_{f\to \infty}\;\frac{1}{2\pi fC}\;=\;0\)

See how that works?
 
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