The superiority of the vacuum circuit breaker is not only oil-free equipment, but also in that it has a long electrical life, mechanical life, large breaking insulation capacity, strong continuous breaking capacity, small size, light weight, frequent operation, With the advantages of avoiding fire, less operation and maintenance, and low failure rate, it is an ideal electrical equipment for unattended substations.
At present, it is being developed and used in large quantities at home and abroad, and has a tendency to completely replace oil arc extinguishing medium. At present, most substations have adopted multi-functional microcomputer (electronic) protection devices, and the degree of comprehensive automation has also increased accordingly, and the requirements for unattended operation have been basically met. Therefore, the main electrical equipment is required to have a certain online detection (self-test) function, and the vacuum circuit breaker should not be an exception.
Common failures of vacuum circuit breakers mainly manifest in two parts:
(1) Mechanical failure. Since the failure rate of this type is relatively small compared with the electrical failure rate, the implementation of online detection still needs to be further unified by the relevant departments in terms of structure, size, and combination.
(2) Electrical failure. This kind of failure is the main problem that directly threatens the safe, durable and stable operation of the power grid, and its probability cannot be ignored. As far as an electrical failure of a vacuum circuit breaker is concerned, compared to a mechanical failure, not only the nature of the failure is serious, but also it is relatively concealed, sudden, random, and difficult to predict in time.
On-line detection method to solve vacuum circuit breaker
At present, there are many online detection methods for vacuum circuit breakers, and the common ones are as follows: ①capacitance induction method; ②artificial neutral point method; ③high voltage electric
In addition, there is an on-line measurement method for vacuum circuit breakers using the Penning discharge principle (electromagnetic wind).
To sum up, each has its own characteristics. Although they can also obtain the signal that the breaking capacity of the vacuum circuit breaker is reduced due to air leakage in the vacuum interrupter under certain circumstances, and achieve the purpose of alarming and blocking through electrochemical processing. There are still many issues to be discussed in order to fully promote the use.
If this type of method is widely used, and some vacuum circuit breakers https://www.misumi.com.cn/seojingtai/xiaoxingduanluqi.html are overhauled or faulty, it is obvious that they are a virtual ground point formed between the main system and the ground, Therefore, in the calculation of the fixed value of safe work and relay protection, the organizational scheme of the distribution network must be considered.
As for other solutions, it is inevitable that they are large in size, complicated in structure, poor in anti-interference, low in shock resistance, difficult to transmit data remotely, and only effective for glass casings or vacuum circuit breakers that are easy to observe. Therefore, the practical impact and feasibility of these methods must be carefully considered when popularizing and actually adopting them.
In fact, the online detection of vacuum circuit breakers can also be realized by other methods, and it is not very complicated. The interest of this subject is to measure the negative pressure variation of the vacuum interrupter. Its main point is that the online detection device itself must not only have good electrical insulation capability, small size, and reliable operation performance, but also have safety regulations, reasonable standards, convenient use, minimal maintenance, and stable cycle. In addition, it must have the dual functions of data remote transmission and local notification, and the communication must also have standard transmission characteristics, which cannot be different from the relay protection.
Implementation of specific methods
The basic method of realization is to use mechanical sensors to change the refraction angle and conductance of the optical signal transmitted by the optical fiber to change the transmission amount of the optical fiber at the receiving end, and then through the subsequent processing circuit to distinguish, process, communicate, etc., so as to achieve online detection. Purpose. The benefits of using this method are:
(1) It can well solve the insulation problem of high-voltage electrical appliances to the ground.
(2) The detection sensitivity is not only practical but also relatively high.
(3) It has relatively strong resistance to photoelectricity, magnetic field, radiation, vibration and environmental pollution, etc.
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