In operation, the leakage mechanism of the hydraulic mechanism of the circuit breaker is unavoidable. Under the rated gauge pressure (opening state or closing state), the hydraulic pressure is not more than 2 times. , indicating that the hydraulic mechanism has leakage.
Leakage of hydraulic system is usually divided into external leakage and internal leakage. 2 types of internal leakage can be divided into: closing leakage, opening and closing; opening leakage, closing without leakage;
1 Reasons for leakage and treatment 1.1 The main cause of leakage is that the tightening torque of the pipe joint is not enough, the joint is loose; the installation is not proper, the joint is stressed and the deformation is damaged.
1.2 The main treatment method Replace the sealing ring and gasket (the copper pad pays attention to the softening to make it soft, it is best to be successful once installed, otherwise the copper pad is easy to produce new leakage points after several times of assembly and disassembly) Hu Fangtao (1965- , male, Wuhan, Hubei, senior technician of Wuhan Yangluo Power Plant.
2 Internal leakage causes and treatment 2.1 The main cause of internal leakage is the damage of the dynamic and static seals and gaskets of the hydraulic components; the seal of the cone valve and the seat is damaged, the ball valve and the valve line are damaged, and the valve line width is greater than 0.2mm; The leakage phenomenon in the key part of the oil leakage point may be the closing leakage, the opening and closing of the control valve, the secondary valve self-holding cavity ball valve and the valve line sealing failure (see) when the switch is in the closing position, due to Keep the cavity ball valve sealed poorly, so that the cavity pressure is not enough. A cone valve closing is not in place, so that the oil drain valve of the secondary valve is not tightly sealed, the high pressure oil is pulled out from the oil discharge valve of the secondary valve, and the low pressure oil return pipe of the control valve is returned to the low pressure oil tank, causing the inner leakage A cone The sliding combination seal of the valve and the valve line sealing of the A-cone valve are in the process of switching and closing operations, and the sliding combined seal of the A-cone valve is moved up and down together with the A-cone valve. Therefore, the sliding combination sealing ring is easy to be worn and aged, thereby causing the high-pressure oil in the holding cavity to the drain valve port of the secondary valve when the switch is closed, and returning to the low-pressure fuel tank through the low-pressure oil pipe of the control valve, resulting in Leakage and the valve line of the A-cone valve may cause damage to the valve line or metal impurities to stay on the valve line due to impurities in the oil, especially metal impurities, resulting in poor sealing and sealing of the valve line. As the service life of the switch increases, the A-leaf valve When the valve line becomes thicker, the switch will be in the closing position, the sliding combination seal of the A-cone valve to the oil discharge valve of the third-stage valve and the three-stage valve cone valve and the oil discharge valve for the oil discharge are poorly sealed (see). When the switch is in the closing position, the instantaneous high-pressure oil in the three-stage valve will be sealed to the low-pressure return pipe due to the sliding combination of the three-stage valve poppet valve, returning to the low-pressure fuel tank, causing internal leakage, and the three-stage valve row The oil valve and the oil drain valve for the oil discharge valve are not tightly sealed, and the direct high pressure oil is directly caused to leak through the oil discharge valve to the low pressure return pipe, causing leakage.
The static combination seal of the control valve is not strict. When the switch is in the closing position, the static combination seal of the control valve is not strict, which will cause the constant high pressure oil in the internal cavity of the secondary valve to directly slam into the control valve space, and return to the low pressure with the low pressure return pipe. tank.
The oil supply valve of the secondary valve of the control valve is not tightly sealed (see) When the switch is in the position of the valve, the oil supply valve of the secondary valve of the control valve is poorly sealed, which will cause the high pressure oil in the secondary valve to be secondary. The valve is drained from the valve, and the oil supply valve of the third-stage valve of the low-pressure fuel tank and the fuel supply valve of the oil-discharge valve are sealed through the low-pressure return pipe. (See) When the switch is in the open position, the seal is poor due to the above. Both will cause the high-pressure oil of its hydraulic components to pass through the oil-discharging valve to the low-pressure return pipe, and return to the low-pressure oil pipe to produce the internal leakage and internal leakage phenomenon, which is the combination of the leakage and the leakage of the constant high-pressure system. The common high-pressure part of the split-and-close system, such as the oil supply valve of the closing first-stage valve, may cause the high-pressure oil to seep through the drain valve of the first-stage valve when the switch is opened or closed due to poor sealing. , 窜 into the control valve, return to the low pressure fuel tank through the low pressure oil pipe.
Leakage of the oil drain valve is often used during the maintenance process of the oil discharge valve, so that the valve core is loose or the operation is not closed and the valve line is damaged, the normal high pressure oil is sucked to the low pressure oil tank, and the internal leakage safety valve is not closed tightly. When the safety valve is not tightly closed or the valve line is damaged, the high pressure oil will be returned to the low pressure oil pipe through the low pressure return pipe.
2.3 The main method used to determine the specific leakage point is: according to the phenomenon, the switch is in the state of opening or closing, and the rated oil pressure is established, and the key parts that may see oil leakage are “touchedâ€, “listen†and “seeâ€. It refers to whether the suspected oil leaking part is heated or the temperature is significantly higher than other parts by hand; listening means listening to the hydraulic component for leaking sound; seeing is to observe whether the hydraulic component is simmering oil and for the low pressure return pipe Observation 4 Processing After finding a specific leak, the processing is easy. If the moving and static seals, gaskets are damaged or aged, replace the seals and pads.
If the valve line is damaged, it can be ground with 400~600 grinding paste, but the width of the valve line must not exceed 0.2mm. If it is necessary to replace the ball valve, replace the qualified ball valve and re-tap the sealing line.
When assembling hydraulic components, it is important to pay attention to the assembly quality and the cleanliness of the workpiece before assembly, otherwise the leakage will be difficult to handle.
3 Typical Cases for Handling Leakage 1 Yangluo Power Plant No. 31 Circuit Breaker (Yang 31) Oil Leakage Treatment Phenomenon: “Yang 31†points and closings are leaking, and the pressure is compensated every half hour. The external no leakage point is judged: High-pressure system leakage or drain valve leakage treatment: the switch is opened, hit the rated pressure, the oil of the low-pressure fuel tank is discharged, and the motor power supply "touch" and "listen" have not found the seepage point. After about 20 minutes, the low pressure The fuel tank is cleaned again, the residual oil is wiped off, and the oil return pipe of the low pressure fuel tank is observed. It is found that the control valve is low pressure back (down to page 61), but due to the large gear range, the ground wire is oscillated in the case of thunderstorm. The amplitudes are different and the ground wire protection range of the ground wire is far greater than 20°. From the past accidents, lightning strike wires are more common, especially in large gear sections.
(3) The grounding resistance of the Yanqi line pole tower is relatively large, with an average range of 20 ~ 3n. The counter-attack voltage formed after the lightning striking tower or grounding line is too high, which easily causes the porcelain bottle string to flash.
In view of the above situation, the main measures taken in the lightning protection of the Yanqi line in 1998 were: the reconstruction of the grounding grid with high grounding resistance of 67 base towers; the detection of all the 457 base tower porcelain bottles by live working, and the discovery and replacement of 302 pieces. Porcelain bottle; the distance from the jumper support tube to the lightning protection line is adjusted from the original 1.1m to 1. 7m and above; for more than 30 lines across the line due to insufficient slope cutting measures, in recent years, the line has obvious lightning protection effect, despite thunderstorm Still strong, but the line did not jump once due to a lightning strike.
2 wire dancing problems Enshi mountain terrain, landforms, climate change anomalies, line operation is also becoming more and more serious wire dance action as a special landscape, frequent occurrences in recent years, has seriously threatened the safe operation of the line. The basic phenomenon is: in the summer of May to August, the weather is sultry, then heavy rain, the geese line part of the leeward and across the 撮箕 terrain section (the length of the gap is different) three-phase wire dances, the dancing frequency is visually measured, about 1Hz The amplitude of the dance is proportional to the size of the rainfall. The maximum peak of the dancing peak is 0.5m. The 220kV line has a total of 4 gears and the phenomenon of wire dancing has been preliminary with the experts of the Provincial Electric Power Research Institute. According to the analysis, this phenomenon belongs to the class of wire corona galloping, which is relatively rare in China. This is mainly due to the small cross section of the wires used in the two 220kV lines, the initial corona voltage is low, in certain geographical environment and climatic conditions and external forces. Under the action of vertical falling raindrops and updrafts, the ray line No. 363 is a heavy ice area with an altitude of 1277.8~1741.9m. The geographical environment is complex, climate change is impermanent, and the line is covered with ice. From the thickness of the ice tested in the field for more than 60 days, the diameter of the wire icing is about 10~20cm, which is greater than the number of accidents related to the ice damage since the line is put into operation. Introduction No. 344 and No. 352 are caused by ice coating on the wire, and one 10kV line under section 342-343 of the 2 pylon reversal line rebounds after ice filling. The A phase is grounded to the 350351 tower B phase wire after icing. After the branches were discharged, an ice-breaking ring was installed on the wire to prevent the ice from melting on the line when the ice layer fell off, causing the distance to the ground to be insufficient, but the ice-breaking ring was easy to aging and falling off, and the icicle formed on the wire was easy to break the ice. Ring coverage, so the role is not big 4 prevention measures Lightning protection of transmission lines is a comprehensive management work, the lightning strike form in the Enshi mountain area is mainly to circumvent and counterattack mostly, direct lightning is less. According to the existing lightning protection experience in China, the protection angle of the ground wire to the wire should be adjusted in the pole section of the lightning strike-prone area, generally below 15°. For high towers, large spans and large spans, the coupling ground line should be erected while increasing the length of the insulator string (within the allowable range of wind bias) and reducing the grounding resistance of the tower can effectively reduce the lightning trip rate of the transmission line caused by corona. The wire dancing is rare at home and abroad. Although the anti-vibration hammer is added to the wire dancing rod section, the form has improved, but the problem has not been solved fundamentally. The next step is to install a voltage equalizing ring on the wire to improve the electric field. Increasing the halo voltage At present, it is considered to add a heavy hammer to the wire, and the wire will be twisted after the ice is covered to reduce the wire coating area = (Continued from page 56). The oil return abnormality of the pipe, open the three-phase control valve sealing cover, observe It is found that the B-phase closing gate first-stage valve is always simmering oil at the high-pressure pipe joint (see), the hydraulic pressure of the hydraulic mechanism is released, the pipe joint is tightened, and the pressure is divided and closed respectively. 3.2 Yangluo Power Plant No. 38 Circuit Breaker (Yang 38) During the 30s period of oil leakage treatment, the A-phase control valve hears a distinct “click†sound, and when it is combined several times, sometimes it is not. The duration is short and the “beep†sound is not, and when it is opened, there is no, the closing pressure is unqualified. , pass the pass. Judgment: Because the oil leakage sound is always within 0~30s, the hard seal (valve line) is unlikely to be damaged, and the sliding seal seal of the A-cone valve and the static combination seal are more likely to be damaged, and the rubber seal is not damaged much. Under the action of high-pressure oil, the ring may gradually seal the high-pressure pool: the switch is in the closing position, the oil pressure is the rated pressure, the oil of the low-pressure fuel tank is drained, the motor power is turned off, and the A-phase control valve sealing cover is removed. Observe, find that the oil drain at the lower oil drain valve of the secondary valve (see) vents the hydraulic pressure of the hydraulic mechanism, replace the sliding combination seal ring of the A-cone valve and the static combination seal ring of the control valve, and separately seal and seal the pressure. No leakage when closing, "Yang 38"
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