I、 Concept: Refers to the distortion of current or voltage waveforms, which is a sine wave component that is an integer multiple of the fundamental frequency. For example, in a 50Hz power system, 100Hz, 150Hz, 200Hz, etc. are all harmonics.

II、 Causes: Mainly caused by nonlinear loads, such as frequency converters, switching power supplies, arc furnaces, rectifiers, and other equipment.

III、 The hazards of harmonics:

1. Equipment overheating: Harmonics increase the copper and iron losses of the equipment, causing an increase in equipment temperature and shortening its service life. 

2. Protection device misoperation: Harmonics may cause relay protection device misoperation, leading to unnecessary power outages. 

3. Communication interference: High frequency harmonics may cause interference to communication signals, affecting communication quality. 

4. Measurement error: Harmonics can affect the measurement accuracy of the electricity meter. 

5. Power factor reduction: Harmonics will reduce the power factor of the system, increase reactive power, and cause energy waste.

XZT 7111 High Voltage Circuit Breaker Tester