⚡ 3rd Harmonics Interactive Simulation
See how the 3rd harmonic changes an AC waveform and why it matters in electrical systems.
What is a 3rd Harmonic?
A third harmonic is a sinusoidal component whose frequency is three times the fundamental frequency. For a 50 Hz electrical system, the 3rd harmonic is 150 Hz. For a 60 Hz system, it is 180 Hz. It is produced when a normally sinusoidal voltage or current becomes distorted by nonlinear electrical loads.
A third harmonic is a sinusoidal component whose frequency is three times the fundamental frequency. For a 50 Hz electrical system, the 3rd harmonic is 150 Hz. For a 60 Hz system, it is 180 Hz. It is produced when a normally sinusoidal voltage or current becomes distorted by nonlinear electrical loads.
Fundamental: sin(ωt)
3rd Harmonic: A₃ × sin(3ωt)
Distorted Wave: sin(ωt) + A₃ × sin(3ωt)
3rd Harmonic: A₃ × sin(3ωt)
Distorted Wave: sin(ωt) + A₃ × sin(3ωt)
Fundamental Frequency
50 Hz
3rd Harmonic Level
20%
Harmonic Phase
0°
Fundamental
3rd Harmonic
Combined Waveform
🔌 What Causes It?
- Switch-mode power supplies
- LED lighting drivers
- Computers and electronic equipment
- UPS systems
- Variable-speed drives
- Other nonlinear loads
🔥 Possible Effects
- Neutral conductor overheating
- Transformer heating
- Extra losses in cables
- Voltage waveform distortion
- Reduced equipment efficiency
- Possible nuisance tripping
⚠️ Why is the 3rd Harmonic Special?
In a three-phase four-wire system, triplen harmonics such as the 3rd harmonic can add together in the neutral conductor rather than cancelling in the same way as the fundamental currents.
Therefore, a significant 3rd harmonic current can cause unexpectedly high neutral current and heating.
⚠️ Is 3rd Harmonic Dangerous?
LOW LEVEL — Usually manageable
At this harmonic level, the distortion is relatively small. Harmonics should nevertheless be monitored in sensitive or heavily loaded electrical systems.
Important: A harmonic is not automatically dangerous.
The risk depends on its magnitude, the electrical system design,
neutral conductor loading, transformer capacity, equipment sensitivity,
and the total harmonic distortion (THD). High harmonic currents can
create excessive heating and equipment stress.