Auto Reclosing Circuit Breaker is widely used in overhead line transmission and overhead line power supply lines on the effective anti-accident measures (cable transmission, power supply can not be used).

That is, when the line fails, after the circuit breaker is tripped by relay protection, the automatic reclosing device closes the circuit breaker again after a short time interval. In most cases, line faults (such as lightning stroke, wind damage, etc.) are temporary. The insulation performance (insulator and air gap) of line can be restored after circuit breaker tripping, and the reclosure can be successful, which improves the reliability of power supply in power system.

The minimum interval allowed for reclosing is 0.15 to 0.5 seconds. The higher the rated voltage is, the longer the insulation deionization time is. The success rate of Auto Reclosing Circuit Breaker depends on the line structure, voltage level, meteorological conditions and main fault types.

According to the statistics of China's power sector, it can reach 60% to 90%. Another widely used anti-accident measure in power sector is the automatic input of standby power supply, which usually takes 0.2-0.5 seconds. It does not require much investment and the economic benefits of maintaining normal power supply are great.

The main functions of automatic reclosure are:

1. PV Auto Reclosing greatly improves the reliability of power supply and reduces the number of power outages, especially for single-circuit lines with one-side power supply.
2. Reclosing on high voltage transmission lines can also improve the stability of power system running side by side.
3. In the process of design and construction of power grid, in some cases, the double-circuit line can be postponed to save investment due to the consideration of reclosure.
4. It can also correct the wrong tripping of circuit breaker itself caused by bad mechanism or misoperation of relay protection.

The economic benefit of PV Auto Reclosing should be measured by the national economic loss caused by power outage when there is no reclosure. Because the reclosing device itself has low investment and reliable operation, it has been widely used in power system.

Starting mode of Auto Reclosing Circuit Breaker

There are two starting modes for automatic reclosure: one is that the position of circuit breaker control switch does not correspond to the position of circuit breaker, and the other is that of protection start.

Advantages of non-corresponding start-up mode: simple and reliable, can also make up for and reduce the impact and loss caused by circuit breaker mis-touch or sneak trip, can improve the reliability of power supply and stability of system operation, has good operation effect in all levels of power grid, is the basic start-up mode of all PV Auto Reclosing. The disadvantage is that when the auxiliary contacts of the circuit breaker are not in good contact, the wrong starting mode will fail.

Protection startup mode is not a supplement to the boot mode. At the same time, in the process of single-phase reclosure, some protective blockades are needed, phase selection and fixing of the fault phase are needed in the logic circuit, and a reclosure starting element is also needed. Its disadvantage is that it can not make up and reduce the impact and loss caused by the malfunction of the circuit breaker.