PDA

View Full Version : Harmonic Filter Resonant Frequency Calculation


ElectricalTestTech
April 19, 2019, 10:55 AM
Which order harmonic would be effectively removed from a power system by applying a single-tuned filter with a 0.55 μF capacitor and a 500 mH inductor?

How do you calculate this?
Wanderer20001us
April 23, 2019, 10:59 AM
Which order harmonic would be effectively removed from a power system by applying a single-tuned filter with a 0.55 μF capacitor and a 500 mH inductor?

How do you calculate this?

I believe the formula is 1/(2PI*SQRT(LC))
kchenoweth
April 23, 2019, 01:45 PM
I believe the formula is 1/(2PI*SQRT(LC))

Can you walk us through this calculation? I have tried doing it several times and haven't come up with what they say is the correct answer yet.
Wanderer20001us
April 23, 2019, 05:20 PM
Can you walk us through this calculation? I have tried doing it several times and haven't come up with what they say is the correct answer yet.

L*C =0.5*0.00000055=0.000000275
sqrt(0.000000275)=0.0005244
2pi*0.0005244=0.003294
1/0.003294=303.49hz
303.5hz/60hz=5.058 or 5th Harmonic
SecondGen
June 14, 2020, 07:56 PM
I've seen a slightly different version of this question:

A harmonic filter bank consists of a capacitor bank at 8uF and 40mH. Which harmonic is this bank eliminating?

f = 1 / (2 * pi * sqrt(L * C))
f = 1 / (2 * pi * sqrt(0.040 * 0.000008))
f = 1 / (2 * pi * sqrt(0.00000032))
f = 1 / (2 * pi * 0.00056568542)
f = 1 / (0.00355430631942971339162580115316)
f = 281.35

Harmonic @ 60 Hz = 281.35 / 60 = 4.689 = 5th harmonic