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Harmonic order - refers to the multiples of fundamental wave frequency, relative to fundamental
wave. If the frequency of mains supply is 50Hz, the 2nd harmonic is 100Hz AC component, the
3rd harmonic is 150Hz AC component and so on.
Channel indicator -- the harmonic state of the channel currently tested.(six channels are
respectively:);
Odd order harmonic distortion rate - refers to the percentage of the total effective value of odd
harmonics relative to the effective value of fundamental wave, defined as follows:
In case of
Then, odd aberration rate
Even order distortion rate - refers to the percentage of the total effective value of even harmonics
relative to the effective value of fundamental wave, defined as follows:
In case of
Then, the even order distortion rate
Then, the total harmonic distortion
Total harmonic distortion——refers to the percentage of the total effective value of harmonics
relative to the effective value of fundamental wave, defined as follows:
In case of
Then, the total harmonic distortion
The scale line - the biggest harmonic is full.
Harmonic pollution to power grid is becoming more and more serious, so the harm caused by
harmonics can not be ignored, mainly reflected in:
1. Greatly increasing the chance of resonance in power grid, thus causing the risk of accidents
arisen from very high overcurrent or overvoltage;
2. Increasing additional loss, and reducing the efficiency of power generation, transmission and
power equipment and the equipment utilization;
3. Increasing the losses to electrical equipment (rotary motors, capacitors, transformers, etc.),
accelerating the insulation aging, and thus shortening the service life;
4. Enabling the relay protection and automatic device, computer systems, and a lot of electrical
equipment to run abnormally;
