With the advantages of good arc extinguishing characteristics, suitable for frequent operation and long maintenance cycle, high-voltage vacuum circuit breaker has been widely used in China's power industry urban and rural power grid transformation, chemical industry, metallurgy, railway electrification and mining industries, and has been widely praised by the user department.
The advantages of using high-voltage vacuum circuit breakers mainly refer to the vacuum interrupter, but its characteristics of long maintenance cycle do not mean that it is not overhauled and maintenance-free. For the vacuum circuit breaker as a whole, the vacuum interrupter is only a component element, such as the operating mechanism, transmission mechanism, insulators, etc., which is still an important part of ensuring the technical performance of the vacuum circuit breaker. It is very necessary for the normal maintenance of each component to achieve the satisfactory use effect of the vacuum circuit breaker.
1 Installation requirements for vacuum circuit breakers
When the vacuum circuit breaker is not committed to the manufacturer, it is necessary to use the site for routine routine inspections to avoid blind confidence as much as possible.
(1) Before installation, the vacuum circuit breaker should be inspected externally and internally, and the vacuum interrupter, all parts and components should be complete, qualified, non-destructive and free of foreign objects;
(2) Strictly implement the requirements of the installation process regulations, and the specifications of the fasteners installed by each component must be selected in accordance with the design regulations;
(3) The distance between the inspections and the position distance between the upper and lower lines must meet the requirements of the relevant technical regulations;
(4) The tools used must be clean and meet the requirements of assembly, and the screws should be tightened around the arc extinguishing chamber, and live wrenches should not be used;
(5) Each rotating and sliding part should move freely, and the friction part of the movement should be coated with lubricating grease;
(6) After the overall installation and commissioning are qualified, they should be cleaned and wiped, and the adjustable connection parts of each part should be marked with red paint, and the wiring at the outlet end should be coated with anticorrosive grease.
2. Adjust the mechanical characteristics of the vacuum circuit breaker in use
Usually, when the vacuum circuit breaker is debugged at the factory, its mechanical properties such as opening distance, stroke, contact stroke, three same periods, opening and closing time, speed, etc. are relatively complete debugging, and the commissioning record is attached with it. Generally, in use, the site only needs to adjust the three same periods, opening and closing speed and closing bounce slightly, and then it has the conditions for operation.
(1) Adjustment of the same period:
For the phase with the difference between the opening distance of closing and opening in the test, if the closing is too early or too late, the opening distance is slightly increased or smaller, and only the adjustable union of the insulating tie rod needs to be screwed in or out of half a circle, which can generally be adjusted to make the different periodicities of closing and opening reach less than 1mm, so as to obtain a more ideal parameter value for the same period.
(2) Adjustment of closing and opening speed:
The speed of closing and opening is affected by many factors, and the only parts that can be adjusted at the use site are the opening spring and contact stroke. The tightness of the opening spring has a direct impact on the closing and opening speed, while the contact stroke (refers to the compression of the contact pressure spring) only has a major impact on the opening speed. If the closing speed is high and the opening speed is low, the contact stroke can be increased slightly, or the opening spring can be tightened a little; On the contrary, the tone is looser. If the closing speed is more appropriate, and the opening speed is low, the total stroke can be adjusted to increase it by 0.1~0.2mm, and the contact stroke at all levels is increased by about 0.1~0.2mm. Its opening speed will also increase; On the contrary, when the opening speed is too high, the contact stroke can also be adjusted by 0.1~0.2mm, and the opening speed will also be reduced.
When the adjustment of the three same periods and the closing and opening speeds is completed, remember to re-measure and correct the opening distance and contact stroke, and should comply with the relevant regulations of vacuum circuit breaker products.
(3) Elimination of closing bounce:
Vacuum circuit breakers generally have the problem of contact bounce during closing. The main reasons for its occurrence are analyzed: first, the rigidity of the closing impact is too large, resulting in the axial rebound of the moving contact; the second is that the moving contact rod is poorly guided and shakes too much; the third is that the gap in the transmission link is too large; Fourth, the perpendicularity between the contact plane and the central axis is not good, and the lateral slippage occurs when it collides.
For the products that have been formed, the rigidity of the structure of the whole machine is a foregone conclusion, and the site generally cannot be changed. For the poor guidance of the moving contact rod, in the coaxial structure, the contact pressure spring and the conductive rod are directly connected, and there is no intermediate transmission part, so there is no gap. For the vacuum circuit breaker with off-axis structure, there is a steering triangle arm between the contact spring and the moving contact lever, which is connected by three pins, so that there are three gaps, and the bounce in the closing process is easy to appear, which is the key point to eliminate the bounce. At the same time, attention should be paid to the adjustment of the transmission gap between the beginning and pressure end of the contact spring and the conductive rod, so that the transmission link is as compact as possible and there is no buffer clearance; If the arc extinguisher contact face is not vertically vertical and bounces, the arc extinguisher can be rotated 90 °, 180 ° and 270 ° respectively to find the upper and lower contact surfaces to coincide, and the arc extinguisher needs to be replaced when it is really not possible.
When dealing with closing bounces, remember to tighten all the screws to avoid being disturbed by tremors.