Why is the harmonic current on the null line mainly three times? This is due to two reasons: (1) Among the harmonic components generated by single-phase rectifier circuit, the third harmonic is the largest, and the distortion rate of the third harmonic usually reaches more than 80%. (2) The harmonic current of other times will have the effect of canceling on the zero line, onl...
What is power quality? The IEC (1000-2-2/4) standard defines power quality as follows: power quality refers to the physical characteristics of power supply devices that do not interrupt or interfere with users' use of power under normal working conditions. The most serious power quality problems are voltage sags and complete voltage interruptions. In fact, power quality refers to the...
Three-phase lines are common: three-phase three wire, three-phase four wire The three - phase three - wire system is star connection neutral point ungrounded and Angle connection method, the general high - voltage power supply uses three - phase three - wire system, three - phase four - wire is star connection neutral point grounding, low - voltage system uses three - phase four - wire system. &nb...
Research background Because the value of harmonic loss is smaller than that of fundamental loss and the calculation is difficult, it is generally ignored in the theoretical calculation of line loss. However, with the development of power electronics technology, the nature of power generation and electrical equipment is becoming increasingly complex, and various nonlinear components put into ...
What is EMC testing EMC test (Electro Magnetic Compatibility) refers to the comprehensive evaluation of electromagnetic interference (EMI) and anti-interference capability (EMS) of electronic products. It is one of the most important indicators of product quality. The measurement of electromagnetic compatibility consists of test sites and test instruments. The purpose of EMC test is ...
The existing power grid is usually equipped with a large number of nonlinear electronic components. These nonlinear electronic components will generate corresponding harmonics during the working process, among which high-order harmonics will interfere with the electrical equipment in the power grid and seriously affect the power supply. Power quality in the grid. In order to reduce the adverse eff...
Power Factor in Networks Power factor is a measure of the phase difference between the voltage and current in an AC power system. In purely resistive loads (such as an incandescent lightbulb or electric kettle) the current is in phase with the voltage and there is ‘unity’ power factor. Capacitive and inductive loads (such as a capacitor banks or inductive motor respectively) will cause...
Prehistoric era -PT PT is the earliest generation of IGBT. It uses heavily doped P+substrate as the starting layer, on which N+buffer and N-base epitaxy are successively grown, and finally the cellular structure is formed on the surface of the epitaxy layer. It is named because the electric field runs through the entire N-base region at the cut-off time. Its process is complex, its cost is h...