What is the difference between corona, spark and arc of high voltage electrical equipment?- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

韦弗斯新闻动态

最新动态

SF6安全保障专家

专注于SF6气体检测的专业化

135 85763546

What is the difference between corona, spark and arc of high voltage electrical equipment?

发布时间：2016-07-12 来源：ydlcb 浏览次数：38次

In SF6 gas-insulated electrical equipment, the magnitude that causes SF6 gas to decompose and discharge to consume energy is divided into three categories: arc discharge, spark discharge, and corona discharge or partial discharge.

Arc discharge: Under normal operating conditions, the circuit breaker will produce arc discharge when it is broken; When a short circuit fault occurs in the gas chamber, arc discharge will also occur. The discharge energy is related to the arc current.

Spark discharge: A very short time between the air gap capacitive discharge, low energy, resulting in decomposition products and arc discharge decomposition products are significantly different. The spark discharge often occurs during the disconnecting operation of the isolation switch or when flashover occurs during the high voltage test.

Corona discharge or partial discharge occurs because in SF6 gas-insulated electrical equipment, certain components are at a suspension potential, resulting in a local increase in the strength of the electric field, at which time metal impurities in the equipment and bubbles present in the insulator cause corona discharge or partial discharge. Prolonged partial discharge or corona discharge causes SF6 gas to decompose, resulting in the accumulation of corrosive decomposition products in the gas chamber. Partial discharge is a continuous process in which the amount of decomposition products formed in the gas chamber is proportional to the discharge time.

Corona:

corona discharge (corona discharge) The partial self-sustaining discharge of a gaseous medium in an uneven electric field. A common form of gas discharge. In the vicinity of the electrode with a small curvature radius, the local electric field strength exceeds the ionization field strength of the gas, which causes the gas to ionize and excite, and thus corona discharge occurs. When corona occurs, light can be seen around the electrode, accompanied by a hiss. Corona discharge can be a relatively stable form of discharge, or it can be an early developmental stage in the process of non-uniform electric field gap breakdown. Corona discharge is usually generated inside the high voltage transformer, and a lot of heat is generated at the same time of corona discharge. Under certain conditions, the corona can be measured by the hoist network wave.

Arc:

An arc is a gas discharge, a transient spark created by the passage of an electric current through some insulating medium, such as air. Arc discharge is due to deionization between electrodes (What is deionization? Initially understood as a process of dissipation of electric ions on the electrode surface)

Full, the discharge point is not dispersed, and it is formed by continuous discharge at the same place, which is a stable discharge process, when discharging, the explosive force is small and the corrosion is low. Arc is more dangerous than corona, the consumption of energy is very intense, even can ignite plastic, paper, wood, can also be used to cut metal (such as ion cutting machine), arc is better to deal with, strengthen the insulation can be.

Electric spark:

It is a self-excited discharge, which is characterized as follows: there is a high voltage between the two electrodes of the spark discharge before the discharge, and when the two electrodes are close, the medium is broken down, and then the spark discharge occurs. With the breakdown process, the resistance between the two electrodes is drastically small, and the voltage between the poles is also sharply lower. The spark channel must be extinguished in time after maintaining a short period of time (usually 10-7-10-3s), so that the "cold pole" characteristic of the spark discharge can be maintained (that is, the heat energy of the channel energy conversion cannot be transmitted to the depth of the electrode), so that the channel energy acts on a very small range. The action of channel energy can cause the electrode to be corroded locally.

The arc is an AC loop discharge, while the EDM is generally a DC HV discharge, which releases energy through the charging voltage of the HV CAP to break down the dielectric material.

SF6 gas insulated combination electrical apparatus is widely used because of its advantages of small footprint, high reliability, low maintenance and electromagnetic environment friendliness. Under normal circumstances, the SF6 gas insulating medium in the gas chamber of the gas-insulated combination electric appliance has stable chemical properties and is not easy to decompose. However, when there is arc discharge, spark discharge or corona discharge in the gas chamber,SF6 gas will decompose due to strong magnetic field effect, and generate low fluorine sulfide SF5, SF4, SF3, SF2 and SF5 SF1, some low fluorine sulfide will also further react with impurities such as oxygen and water present in the gas chamber to produce stable compounds such as SO2F2, SOF2 and SO2. The existence of these decomposition products will not only reduce the insulation performance of the insulating medium, but also corrode the insulating equipment such as pillar insulators, seriously endangering the long-term safe operation of the equipment.