New technology to improve the breaking performance and drive of high voltage circuit breakers
It is still awesome.
The initial development of the arc chute was based on the thermal effect quenching technique (or self-blowing), ie the arc-extinguishing energy required for the breaking of large currents was obtained by an inherent in-volume gas thermal expansion principle. The self-energizing arc extinguishing aid can disconnect the breaking capacity current below 30%. This allows the gas to greatly reduce the compression energy, thereby greatly reducing the energy of the operating mechanism. Therefore, the arc-extinguishing pistons of these devices are used as the breaking size of 30% of the maximum breaking current. The piston diameter of this size is smaller than the diameter of those of the compressor type, that is, the mass of most movable parts is also reduced. In order to reduce the kinetic energy of the operating circuit breaker 3, the realization from the energy-extinguishing chamber enables the breaking technology to be perfected by the thermal effect and to obtain further reduction of the operating energy and to improve the breaking capacitive current performance. Therefore, the IEC56 standard is ready to introduce a new class of circuit breakers (C2) with a very low level of very low breakdown probability, which will pass three breaks of the circuit breaker at 60% of its rated short-circuit breaking capability. To verify the number of trials.
The arc extinguishing chamber that reduces the compression stroke requires that the compressed gas required to break the small current is generated only during the sliding of the entire contact stroke, typically less than 50% of the total stroke. This principle is as shown.
The circuit breaker breaking is divided into two phases: the first phase, between the 1 and 2 positions, the relative sliding between the piston 8 and the cylinder B, used to compress the gas in the Vc container, and the pressure gas generated at this time will open the sheet. Valve C, then enters the boosting chamber VU in the second phase of the opening, ie between positions 2 and 3, the piston and the cylinder actually pass up together through the exhaust position. The relative displacement of the piston and the cylinder is indicated by Mechanical linkages can also be used to obtain operating power through other mechanical or pneumatic methods. These principles include several patents. In the second breaking phase, no more compressed gas is produced; as a result, the energy provided by the operating mechanism can be reduced to an effective value sufficient to maintain the breaking speed of the transmission. In contrast, the energy required in a self-contained circuit breaker cannot overcome the high pressure (overpressure) generated within the expansion volume Vt. The reaction force only comes from the compression volume Vc: the small pressure generated in the inside = For the breaking small current, the overpressure generated in the compression phase effectively ensures the breaking within the required range of the arcing duration. For breaking large currents, the arc energy is used to increase the gas pressure in the volume Vt. The overpressure generated in this way produces the extinguishing power required for arc extinguishing during the zero crossing of the current.
Described is a high-voltage circuit breaker with a large-current breaking performance and a double-volume interrupter structure, that is, the patent W in the initial state, that is, between positions 1 and 2, the gas rise of the gas supply chambers Vc, Vt and Ve Pressure. In particular, a high-density gas is allowed in the vicinity of the arc generation at the moment of contact separation at position 2. As a result, the dielectric strength between the contacts is increased during small current interruptions. 3 This type of arc extinguishing chamber has a high-performance breaking capacitor current, which is suitable for meeting future IKC standards.
In the second stage, between positions 2 and 3, the gas flow in the gas chambers Vc and Ve flows to the rear through the opening (1) and (2) vent holes and gradually depressurizes. This causes the sheet valve C to be closed, which also causes the gas pressure in the gas chamber Vc to evolve to the gas pressure of Vt, and the gas pressure is increased due to the thermal expansion effect of the arc.
A significant reduction in operating power can also be obtained by reducing the kinetic energy consumed during the breaking. One of the possible methods is to move the two moving arc contacts in opposite directions. This means that the moving contact structure requires only half the speed. It is an example of such a type of arc extinguishing chamber which is a structure that combines a double contact displacement that has reduced the compression stroke.
Compared with automatic pneumatic circuit breakers, the gas compression energy required for the three arc-extinguishing modes is currently reduced by about 1/9. Currently, this second-generation self-energy circuit breaker has been widely used in industrial systems.
The calculation of the size of the self-energizing (thermal expansion) interrupter must use high-performance calculation software. The mechanical properties as well as the breaking performance of capacitive and large fault currents can be predicted.
Therefore, it is indispensable for the manufacturer to use the analog operation of these circuit breakers to determine the position in order to reduce the number of tests required to develop the circuit breaker.
The following are three examples of procedures that are currently widely used in high voltage circuit breaker technology. There are also examples of other more sophisticated techniques with physical model arcs. For example, the GEC Alstom ARTUR principle is used by companies to calculate the time function of gas flow and arc characteristic values ​​throughout the arc chamber.
The precise calculation of the relative displacement of the arc contact and the increase in the displacement of the air pressure generated in the two gas chambers is obtained by integrating the equations of the activity. The acceleration of the piston depends on its mass, the force released by the transmission, and the friction loss is based on the resistance exerted on each pole by the gas in each of the compressed gas chambers causing the pressure to rise.
4 shows 145kV/40kA/-4 (simulation example of TC no-load operated circuit breaker 3 X: displacement of moving part Xp: displacement of moving piston V: speed of moving part ApVt: over-pressure in thermal expansion volume APVc: compression Overpressure gas flow and electric field mixing in the volume Calculating the capacitive current of the open-cut air-to-air line, no-load cable or capacitor bank is one of the main functions of the high-voltage circuit breaker not generating overvoltage in the system (ie no heavy breakdown) For the "capacitive current that guarantees safety and no heavy breakdown, it must be ensured that the voltage level between the two contacts is always higher than the recovery voltage of the power grid after the arc extinguishing. As described in Chapter 2, the future The IFX56 high voltage circuit breaker standard will require capacitive opening and closing in some cases, and the performance should be improved. Therefore, for the designer to master this breaking technology well, the calculated and designed pressure withstand level is It is important.
The voltage withstand capability is a function of the electric field E and the local gas density, which is proportional to the number N of capacity particles in the unit, which can be verified by the reduced electric field E/N.
The software MC3 jointly developed by the Montreal University of Technology can simulate the calculation of the density field of the opening process, the electric field F: and their ratio E/N. The research value is at any point in the breaking process and every moment of the instantaneous recovery voltage Can be won. Dynamic calculation takes into account the displacement of the moving part.
If the gradient of the juice is known to be the maximum allowable K/N (for example, can be obtained by a series of tests performed by x, electrical appliances), then A may calculate the withstand voltage level of other devices or the same device is different. The withstand voltage level under breaking conditions. The breaking terminal fault or the near-field fault current mainly depends on the degree of arc extinguishing at the current zero crossing. This is obtained by the overpressure in the expansion vessel and the mass value 大部分 of the majority of the flow of the gas, which parameters depend on both the movement of the piston and the thermal energy effect obtained within the expansion volume. Therefore, the simulated breaking test is also a step-by-step process for the arc-extinguishing dynamics at the time of breaking and current zero-crossing. The technology developed by GFT Alstom of France can fully simulate this breaking test. It is a device suitable for Dingye or three-pole spring operating mechanism. In order to simulate the thermal energy effect in the breaking phase, a "black box" with pressure and current characteristics is combined in this simulation, which can perform arc resistance (or conductivity). Calculate this program to predict the corresponding arcing time under fault current. According to the characteristics of the grid (voltage, line wave impedance and percentage of line fault current, etc.) and the characteristics of the arc extinguishing chamber (additional capacitance), the transient recovery voltage can be calculated. conditions of.
This procedure is suitable for breaking large short-circuit fault currents (test mode SLF90) and terminal fault currents (test mode T100). It is also possible to simulate a smaller current (test mode T30 and (4)): his terminal fault has determined the breaking criterion of f, so it is possible to ensure that no critical current is present from the initial design stage. In order to confirm this, the r short-circuit breaking current test is performed on the analog board or the prototype circuit breaker.
The current of a 245kV circuit breaker with a ground capacity equal to 12nf is interrupted at 90% 63k/-60Hz. Fourth, the application of the new fire arc principle introduced in 1' has enabled a new circuit breaker to be used. 72.5kV expanded to 55kV outdoor, gas-insulated, fully enclosed combination appliances.
Choosing the appropriate breaking technique is affected by each specific aspect involved in the technical requirements, such as: short circuit and capacitive opening (voltage level and voltage coefficient) performance, energy supplied by the operating mechanism, and standardization of the seeking breaking unit, Therefore, for example, the development of the rear exhaust technology was developed to obtain a higher breaking performance when capacitive opening and closing. In addition, the factors that satisfy the technical economy are important, the degree of standardization is high, and the use of existing main components has a positive effect on the required development time. The dual-volume interrupter can reduce the transmission energy of the vehicle. The breaking function is reliable, and it is explained how the power of breaking and extinguishing arc on the tripping energy function is increased compared with the conventional technology. The arc chutes of 72.5 kV, l45 kV and 245 kV were compared. For higher voltage levels, the current arc extinguishing chambers, due to economic benefits, have led to the development of a new generation of spring-like moving mechanisms with reliable operating energy ranges above 4500, as each level of breaking performance has increased.
Further increasing the utilization of the arc energy makes it possible to ensure the amount of SF6 gas required to reduce the breaking performance. A comparison between the amount of gas required for arc extinguishing and the conventional 72.5 and 245 kV voltages with a two-volume interrupter. To this end, the compressed cold gas in the volume VC can be determined. The expansion volume Vt å±® is the mass of the SF6 gas required to extinguish the arc by multiplying the mass per unit volume of the filling by the mass of the filling. A significant increase in the ratio between the breaking capacity and the gas mass (as seen in the middle) can reduce the total volume of the arc extinguishing chamber. During the break, a small amount of SF6 participates in the conversion of the arc energy. As a result, a small amount of gas in the arc extinguishing chamber is required for insulation to withstand the transient recovery voltage. The breaking capacity as a function of gas mass as a function of voltage variation from 72.5 to 245 kV is illustrated.
In addition, by replacing the breaking element of the existing circuit breaker, it is possible to slightly improve the performance in accordance with the cost value. Therefore, for example, in the currently used tank floor circuit breakers, the breaking performance is from 40kA to 63kA. For further consideration, most of the mechanical and electrical calculations can be greatly simplified, using existing outdoor gas insulated or tank floor circuit breakers. Can shorten development time. The final calculation of the new circuit breaker enclosure shows that the volume of the arc-extinguishing chamber can be reduced by up to 40% a in comparison with the two outdoor circuit breakers -30X: due to the new dual-volume interrupter (front circuit breaker), Thereby reducing the size of the arc chamber porcelain sleeve and the energy delivered by the mechanical drive. Conversely, if a new two-volume interrupter is used for a larger volume interrupter porcelain sleeve (the latter circuit breaker), it is possible to increase its performance to 145kV/40kA/-40°C while maintaining The original drive and housing.
V. Spring operating mechanism uses a compact spring operating mechanism to improve equipment running time and service life The development of a new generation of circuit breakers is based on the long-term operation experience of the equipment and the need to accelerate equipment development. The international symposium shows the total number of high-voltage sf6 circuit breakers currently in operation: 54.5% of the equipment failures, of which 49.3% are defects caused by mechanical structures.
By applying the principle of the current dual-volume interrupter structure, the transmission energy obtained can be greatly reduced, making the use of lighter structures more reasonable.
The factors that drive the mechanical action of the circuit breaker until now are still used. The second-generation mechanical transmission with spring mechanism is operated with a plunging shaft, which includes a relatively high inertial mass (〗). In the closing process, it is accelerated by rotating the disc spring 360 degrees. Finally, the moving part is braked by the arm (2, 3) of the transmission mechanism (Fig. (1)) and most of the remaining closing energy is consumed in the frictional connection. The large force of mechanical release is compensated by the use of bumpers and active components.
During the development of the third-generation spring operating mechanism (1), special attention was paid to reducing the dynamic load. The closing operation operates in a more harmonized manner with a smaller volume, thereby reducing the impact on the mechanism. On the one hand, the crankshaft type closing system (1) has been used on medium voltage circuit breakers; on the other hand, the impact force caused by special cams is low. The solution chosen was to use a lighter mechanism that had an impact on working life and reliability, as the internal energy converted to friction, wear and elasticity and plastic deformation was reduced. Therefore, the development of this technology will reduce the number of parts of the mechanism by about 30%. Table 1 measurement results measured value Spring operating mechanism type 12 maximum acceleration during closing, X (m / 2) 88393 maximum acceleration during closing. Ylm/: ") 88334 maximum acceleration during closing, Z (m / s2) 167461 dynamic force on the connecting rod (kN) 13 load analysis of the circuit breaker operating mechanism in order to determine the movement including two types of spring operating mechanism The load, using the effectiveness of the design concept of the third-generation spring operating mechanism, was tested on two types of operating mechanisms. The first series was equipped with a third-generation mechanical circuit breaker of 245kV, 40kA current. The second series is still being tested on the same circuit breaker, this time being operated by a second generation agency.
Next is the value measured on the drive mechanism on the closing phase: - the acceleration a(t) of the front plate of the mechanism box on the X, Y and Z axes; - the coupling between the circuit breaker and the spring operating mechanism The force of Fl(t).
The opening operation is not a measurement object because the two types of spring operating mechanisms have only one blocking function at this stage. The acceleration force in the mechanism box is mainly generated by the circuit breaker and is of the same order of magnitude (about 300 m/s2) for the two selected objects.
2 made a comparison of the acceleration on the X-axis during a closing operation. The peak acceleration is easily linked to the different phases of the movement (see 0 and 11). For both types of mechanisms, the maximum force and acceleration occur at the end of the closing operation, while the stroke spring is fully expanded, depending on the trip lock (3). In the case of the second generation, essentially the drive shaft on the flywheel (1) has been rotated through a 360 degree angle. That way it finally relies again on the closing lock and produces a higher effect (vector on the Z-X axis, 0 and Figure 丨1). The acceleration associated with this, despite the friction with the flywheel, reaches a value higher than 45g3. The vector of force and acceleration cannot occur in the third-generation spring operating mechanism type. Because the direction of motion of the spring changes uniformly, the connection (1) bears force. Therefore, the remaining closing energy is converted to the closing spring. Therefore, the special geometry of the mechanical type of cam enables the closing spring to naturally stop on the closing lock once it is pressed. The dynamic force and the final static force in the coupling of the circuit breaker can be reduced by half compared to the second generation mechanical type.
2 Comparison of the dynamic characteristics of the third-generation spring operating mechanism and the second-generation spring operating mechanism and the 245kV circuit breaker: A. Starting of the closing shaft (CS) B: Starting of the spindle (MS) C: Friction connection D: Starting of the shaft E: CS and MS coupling G: MS stops at the closing lock, only suitable for the coil spring drive; CS is ready to rest on the closing lock Fit: Coupling force Felt: on the main closing lock Force A(t) measures the X-axis through the 500 Hz acceleration S(t) on the housing: the movement of the polar axis (linear potential ih connected to the mechanism). Table 1 provides a result and shows the second generation mechanism and A comparison of solutions using third-generation institutions. In the same way, the entire closed-end crankshaft mechanism application and cam geometry will be reduced and better than the system's acceleration values.
The velocity resulting from the acceleration is representative of the internal transmission energy conversion within the transmission. This part can. The amount is not available outside the system "operating mechanism", but is converted to friction and deformation energy, which has a long-term effect on the wear and fatigue properties of its components.
The performance and life of the acceleration curve of the third-generation operating mechanism coil spring have a long-term effect.
Table 3VD4C; type generator circuit breaker technical data VD4G constant power n; (press 丨i.: c) kV17.5 rated voltage (according to ANSI/IF: F: E) kV15.8 rated T frequency voltage kV50 rated 'iL electricity Impact electric positive kV (95) 110 rated current (when people 40V), especially ventilation A3400f ventilation A5000 rated breaking current grid power supply (symmetric value) kA40 generator power supply kA25/18.5 rated closing current kA110 VD4G type generator breaker eight 1 - Upper wiring room (such as transformer) - Lower wiring room (such as generator) I; - Circuit breaker room C - Low pressure room 1 - Outlet 2 Qu Peibin review draft n: 2丨丨01丨-US-2S ( With the emergence of the third generation of spring operating mechanism, it is concluded that the r performance is more reliable, the service life is longer, and the economic benefit can be better reflected: the minimum conversion energy inside the transmission mechanism; Optimized use of closing energy; economical efficiency of buffering device; reduction of number of transmission mechanisms and parts of light-structure; - minimum mechanical loss and maintenance, VI. Conclusion SFh breaker breaking technology has been In the past few years, there has been substantial progress. The progress made raises the prospect that a new generation of circuit breakers that minimize operating energy has been replaced by low energy m spring operating mechanisms.
At H, the new generation of spring operating mechanism reduces the impact force generated by the body of the mechanism during operation. In this way, the reliability of the r-circuit breaker is also raised.
These new technologies make it possible to achieve high performance (IEC standard C2 class circuit breakers, with a very low voltage combination, can also interrupt large currents), without the need to increase the circuit breaker's work breaker The evolution has been widely applied to the representative devices in the range of 72.5kV to 245kV, and N will also be applied to future higher voltage level A devices that open and break high current performance (such as power generation). Machine breaker
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