Question

Why $3^{rd}$ harmonic is dangerous?

Answer 1

Harmonic:

1. It is the positive integral multiple of the fundamental frequency.
2. These harmonics are also known as overtones when we discuss sound.
3. Generally, the impedance of the device or circuit is inductive which is equal to $R+j\omega L$, where $\omega =2\mathrm{\pi f}$.
4. Therefore, from the equation, the impedance is directly proportional to frequency.
5. Hence with the increase in the order of the harmonics increases the impedance also increases and so they are less in magnitude compared to lower order harmonics.
6. This makes the circuit block the higher-order harmonics.
7. Hence the filters are designed mostly for lower-order harmonics.
8. Generally, power system harmonics increase the current in the circuit rapidly.
9. The rapid increase in electric current exactly happens at the $3^{rd}$ harmonic making it dangerous for circuits.
10. These harmonics cause malfunctioning of devices and heating.