Gas-insulated Circuit Breaker Research Articles

Recent Development of Two Alternative Gases to SF6 for High Voltage Electrical Power Applications

For many years, SF6 has been the preferred dielectric medium in electrical power applications, particularly in high voltage gas-insulated equipment. However, with the recognition that SF6 has an extremely long atmospheric lifetime and very high global warming potential, governments have pursued emission reductions from gas-filled equipment. The electrical power industry has responded to this environmental challenge applying SF6-free technologies to an expanding range of applications which have traditionally used SF6, including gas-insulated switchgear, gas-insulated circuit breakers and gas-insulated lines or bus bars. Some of these SF6-free solutions include gas mixtures containing fluorinated compounds that have low climate impact, among them, a fluoronitrile and a fluoroketone developed as 3M™ Novec™ 4710 Insulating Gas and 3M™ Novec™ 5110 Insulating Gas, respectively. Both fluoronitrile and fluoroketone mixtures are successfully used in gas-insulated equipment currently operating on the grid where they reduce greenhouse gas emissions by more than 99% versus SF6. This paper reviews these leading components of alternative-gas mixtures with updates on the performance, safety and environmental profiles in electrical power applications.

Design and Development of 220kV SF6 Gas Insulated GIS Actual Testing Platform

To simulate the performance parameters of SF6 gas insulated AC GIS equipment under normal and failure condition in the laboratory environment, and the development trend of characteristic parameters such as partial discharge and SF6 gas decomposition can be monitored periodically and quantitatively, the 220kV SF6 gas insulated GIS type test platform is designed and developed. The test platform is in accordance with GIS specifications used in substation, including gas insulated circuit breaker and other typical GIS equipment. The external voltage is realized by the series resonant circuit. The paper starts from the design of the GIS bus and the solid insulation structure, and the three-dimensional E-field distribution characteristics of the solid insulator are simulated and analyzed. The hardware installation of the partial discharge measurement and SF6 gas decomposition monitoring on GIS model test platform are discussed. Through design and development of 220kV SF6 gas insulated GIS type-test platform, the feasibility of the structure design of GIS bus and the solid insulation are verified, it provides theoretical and practical basis for the operation and maintenance of SF6 gas insulated GIS equipment.

Influence of the shape, number, position and dimensions of conductive particles within inter-electrode gap on dc and pulse breakdown voltage value of SF6 and N2 mixture

The aim of this paper is to determine how the shape, number, position and dimensions of the conductive particles produced during switching operations influence the dielectric strength of the gas-filled switches insulated under pressure which are in the state of open contacts. To this end we have developed a numerical program that makes it possible to calculate dc values of the breakdown voltage of bi-electrode gas-filled system in which conductive particles of defined shape and dimensions are present in inter-electrode gap. The calculation results are empirically tested (and verified) in controlled laboratory conditions. Based on the obtained results suggestions are made as to how to extend the life span of gas-insulated circuit breakers using SF6 and N2 mixture instead of pure SF6.

Electric Field and Current Density Performance Analysis of Sf6, C4f8 and CO2 Gases As An Insulation

SF6 gases are not only widely used as an insulating component in electric power industry but also as an arc extinguishing performance in high voltage (HV) gas-insulated circuit breaker (GCB). SF6 gases is generally used in the production of semiconductor materials and devices. Though these gasses is widely used in many application, the presences of temperature hotspot in the insulations may affect the insulation characteristics particularly electric field and current density. Therefore, it is important to determine the relationship between electric field and current density of gasses used in the insulator in the presence of hotspot. In this paper, three types of gases in particular Sulphur Hexafluoride (SF6), Octafluorocylobutane (C4F8), and Carbon Dioxide (CO2) was used in the insulator for gas insulation with the presence of two hotspots. These two hotspost were detected by referring the rising temperature in the insulator which are 1000 and 2000 Kelvin temperature for hotspot 1 and hotspot 2, respectively. From the simulation results, it can be concluded that Sulphur Hexafluoride (SF6) is the best choice for gas insulation since it had the lowest current density and electric field compared to Octafluorocylobutane (C4F8), and Carbon Dioxide (CO2). It is observed that the maximum current density and electric field for SF6 during normal condition are 358.94 × 103 V/m and 0.643 × 109 A/m2, respectively. Meanwhile, during temperature rising at hotspot 1 and hotspot 2, SF6 also had lowest current density and electric field compared to the other gasses where the results for Emax and Jmax at hotspot 1 are 322.34 × 103 V/m and 1.934 × 109 A/m2, respectively; While, Emax and Jmax at hotspot 2 are 259.77× 103 V/m and 2.824 × 109 A/m2. The results of this analysis can be used to find the best choices of gas that can be used in the insulator.

TCSR Features Facilitating Safe Testing of 500 kV Power Transmission Lines

Reasons are examined for failures of gas-insulated circuit breakers on lines with shunt reactors that provide a level of line compensation close to 100%. It is shown that using a TCSR as a linear reactor makes it possible to eliminate the reason leading to failure of the circuit breaker in line testing.

Application and Recycling of SF6 gas Mixtures in Gas-insulated Circuit Breaker in Northern China

In northern China, very low temperatures stress a circuit breaker in a complex manner. In recent years, we develop mixed-gas circuit breakers utilizing SF6 gas mixtures (SF6/CF4 or SF6/N2) which offer excellent cold-weather performance at temperature as low as -45 °C. The performance of SF6 gas mixtures is different upon the partner of SF6 gas and the gas ratio of the mixtures. We utilized different SF6 gas mixtures in circuit breakers at different system voltages in different areas. Unlike pure SF6 gas, handling and recycling SF6 gas mixtures is a complex job, and it is in urgent need of an outline of handling and recycling SF6 gas mixtures since more and more SF6 gas mixtures insulated equipment are in service. In this paper, we introduce the situation of mixed-gas circuit breakers at different system voltage, and present how to handle and recycle SF6 gas mixtures while the mixed-gas circuit breakers are out of use.

On the applicability of the Mayr arc model for studying current chopping and overvoltages generated by low-oil current breakers

A significant number of low-oil circuit breakers are currently in operation. They are considered obsolete and inferior in their characteristics to more modern types of switches—vacuum and gas-insulated circuit breakers. When triggered, low-oil circuit breakers can serve as sources of considerable overvoltages, one of the causes of which is the current chopping that is connected with the arc-extinction mechanism in a dense environment. Current chopping usually occurs when small inductive currents are disconnected, for example, the no-load current of transformers and electric motors. When arc processes in circuit breakers are investigated, various methods are used, including adaptive ones (the “black box” method). This paper considers the possibility of using the arc model on the basis of the Mayr equation for studying the phenomena of current chopping and overvoltages that are generated by a low-oil circuit breaker. The features of constructing such a model are analyzed, and its structure, appearance, and description are presented. The model was constructed in the MATLAB software package. The case of the RLC-circuit disconnection from a source of a low-resistance EMF was considered taking the arc-extinction mechanism into account. This circuit simulated the switching off of an electric motor that was connected via a cable line. This article also presents s comparison of the experimental and calculated data.

THE DEVELOPED RESOURCE DEFINITION OF GAS-INSULATED SWITCH TYPE H G F 100/2 B, C GEC ALSTHOM FOR A FUZZY MODEL

The purpose of the work is the development of fuzzy model gas-insulated switch type HGF 100/2 B,C GEC ALSTHOM to determine the total mined-out resource.Research methods. The study was conducted through expert interviews, that became the basis for the construction of the fuzzy model of gas-insulated circuit breaker to determine the total mined-out resource. This model is implemented in MATLAB Fuzzy Logic Toolbox using the mathematical apparatus of fuzzy sets and fuzzy logic.The obtained results. The authors developed the fuzzy model which obtained the numerical value of the total resource developed gas-insulated circuit breaker with the influence of aggregate factors such as the condition of mechanical and switching systems, the state of arc suppression medium and isolation.Scientific novelty.The authors developed the new fuzzy model of gas-insulated circuit breaker to determine the total developed resource, which uses the information available for measurement or observation.Practical significance. This model is used for gas-insulated switch type GEC ALSTHOM HGF 100/2C operated on the Dnipro HPS-1, ODD-330 kV, cell L -211/1. The developed fuzzy model of assessment of the gas-insulated switch technical condition can be applied to all switches of this type.

Mass effect analysis of a coil spring for the performance evaluation of a gas insulated circuit breaker

Since the performance of a circuit breaker which has the spring operating mechanism mainly depends on the dynamic behavior of a coil spring, the analysis of the dynamic behavior of a coil spring is required for a performance evaluation of a circuit breaker. When a spring moves so fast from the releasing state, a lot of energy is used to move a self-weight of a spring. Thus, the mass effect analysis of a spring operating mechanism is required for the performance evaluation of a circuit breaker accurately. In this study, a release test bed is designed for evaluating the dynamic behaviors of a coil spring. Three types of spring models such as a linear spring model, a nodal spring model and a lumped parameter spring model are established for comparing the modeling error of a spring due to the mass effect. RecurDyn is employed to carry out the computer simulation and results are compared with test results. The actual energy transferred to the follower during high-speed motion is analyzed through the comparisons of the kinetic energy between the experiment and the computer simulation.

Performance improvement of a gas-insulated circuit breaker using multibody dynamic simulations and experiments

The operating performance, spring characteristics, and material properties of a gas-insulated circuit breaker were optimized using multibody dynamics. The circuit breaker consisted of several latches and a cam. The dynamic behavior of the latches was affected by the spring characteristics, as well as by the materials and length of each latch. Our results indicated that the motion of the latches was a key factor in determining the opening time of the circuit breaker. A multibody model for the circuit breaker was developed and verified by comparing simulated results with experimental data. The opening time for the breaker was reduced by 1.5 ms in simulations.

Gas Insulated Switchgear and Circuit Breaker for Substation

Gas Insulated Switchgear and Circuit Breaker for Substation

Transient response of transformer with XLPE insulation cable winding design

Significant advances in XLPE insulation cables that have higher electric field strength withstand capability have made it possible to apply these high voltage (HV) cables as windings in generators and transformers. Therefore, the recent advent of HV generator (Powerformer) that can be connected directly to the power transmission line has motivated the design of HV transformer (Dryformer) that performs one step transformation from transmission to distribution voltage levels. Since the dryformer will be connected directly to transmission lines, they will be subjected to transients resulting from direct and indirect lightning strikes as well as fast switching surges from Gas insulated circuit breakers. This paper presents the results of experimental studies on the cable winding power transformer (Dryformer) to study its response to various transients. Experimental investigations have been carried to obtain the transformer model parameters based on terminal measurement of admittance functions using Network Analyser, and hence for comparing the model predictions with experimentally obtained responses. The model has been successfully used in estimating the dryformer transient responses at its terminals due to surge application of various front times and peak amplitudes that are representative of lightning and switching caused transients. Experiment and simulation results show that there are considerable differences in the transient response characteristics of dryformer windings as compared to that of transformers with traditional winding design. These differences on transient responses are discussed in perspective of their basic difference in winding design features.

On the Design of Spring-Actuated Mechanism for 69KV SF6 Gas Insulated Circuit Breaker

This paper studies the design of a spring-actuated mechanism of 69KV SF6 Gas insulated circuit breakers. The creative mechanism design method is first used to synthesize all the feasible mechanisms that satisfy the requirements for the circuit breaker. The kinematics of the mechanism are then analyzed using the vector-loop method. Subsequently, the equations of motion are derived with the Lagrange equation and solved by the Runge-Kutta method. The duration of individual operation, and hence the total duration to complete the full cycle of the mechanism has also been calculated. The times taken for the closing and opening operations were found to be 0.116 and 0.076 sec, respectively, comparable with the experiments.

Dynamic response of spring-type operating mechanism for 69 kV SF 6 gas insulated circuit breaker

This paper investigates the dynamic response of a spring-type operating mechanism for a 69 kV SF 6 gas insulated circuit breaker. This paper uses the equation of motion to analyze the dynamic response of the spring type operating mechanism. The basic theory behind the equation of motion is briefly introduced and the kinematic coefficients of the links and the centers of gravity of the spring-type operating mechanism are then derived. The non-linear differential equation of motion is then solved by using the fourth-order Runge–Kutta method. From these results, the duration of each operation is then calculated. It is shown that the closing time is 0.114 s and the opening time is 0.078 s which are comparable with those obtained experimentally. In addition, the dynamic response of the output moving contact has also been calculated and comments are made on its kinematic characteristics.

On the dynamics of a spring-type operating mechanism for a gas-insulated circuit breaker in open operation using the Lagrange equation

This paper investigates the dynamics of a spring-type operating mechanism of a gas-insulated circuit breaker in open operation. The vector-loop method is first used to derive the position, velocity and acceleration functions of each member of the operating mechanism. The equations of motion of the mechanism are then formulated using the Lagrange equation and solved by the fourth-order Runge-Kutta method. It has been shown in the analytical results that the breaking time of the circuit breaker is 0.076 seconds, which compares well with the experimental results.

On the dynamics of spring-type operating mechanism for 69 KV SF 6 gas insulated circuit breaker in open operation

This paper investigates the dynamic response of a spring-type operating mechanism of a SF 6 gas insulated circuit breaker in open operation. For a single degree-of-freedom rigid mechanical system subjected to external forces, its motion can be represented by a second order non-linear differential equation. In this paper, the vector-loop method is employed to derive the kinematic coefficients of all the members of the spring-type operating mechanism and their centres of gravity. The equation of motion is then solved using the fourth order Runge–Kutta method. The analytical results revealed that the breaking time of the circuit breaker was 0.078 s, a mere 5% difference from the experimental result. The dynamic response of the circuit breaker with different spring constants was studied and its effect on the breaking time was also assessed. With the dynamic response known, the input driving torque of the circuit breaker can also be computed from the equation of motion.

On the transmission efficiency of a spring-type operating kinematic mechanism for an SF<SUB>6</SUB> gas-insulated circuit breaker

On the transmission efficiency of a spring-type operating kinematic mechanism for an SF<SUB>6</SUB> gas-insulated circuit breaker

On the transmission efficiency of a spring-type operating kinematic mechanism for an SF6 gas-insulated circuit breaker

The purpose of this paper is to study the transmission efficiency of a spring-type operating kinematic mechanism for an SF6 gas-insulated circuit breaker. This mechanism has two degrees of freedom, which, when operating in the open, close, or return mode, becomes a single degree of freedom by fixing a link that adjoins the frame to achieve specific requirements. Firstly, the vector-loop method is employed for position analysis of the links of the mechanism. Subsequently, by using coordinate transformation and the geometry of the cam and the follower, the relationships between cam rotation and the position of the linkage follower in the close operation, as well as cam rotation and the position of the motor-switch follower are established. Based on the transmission angle of the linkage and the pressure angle of the cam mechanism, the transmission efficiencies of the mechanism are evaluated and discussed. The mechanism is also computer simulated and the transmission angle is optimized using the augmented Lagrange multiplier (ALM) method. The results show that the optimized parameters noticeably improve the transmission angles of the present design.

Investigation of technology for developing large capacity and compact size GCB

New effective technologies to increase the interruption capacity and to the reduce size of a gas-insulated circuit breaker (GCB) are shown. One is the adoption of a new nozzle shape that improves the cooling of the arc. The other is the investigation of hot gas diffusion in the exhaust cylinder related to the dielectric strength recovery after the current interruption. It is shown that these technologies are useful for increasing the interrupting current from 50 kA to 63 kA.

Protection of SF6 Gas Insulated Substations - Industry Survey Results

This paper summarizes the result of an industry survey of gas insulated equipment protection practices and develops recommendations where necessary. Tables are included to show the type of gas insulated equipment located at each substation (current transformers, voltage transformers, switches, bus bars, bushings, lightning arresters, and cable end terminations), the equipment configuration (single or three conductors), the type of gas monitoring equipment used (density or pressure), the use of gas monitoring equipment (alarm and/or trip), unique relaying protection applications, and unique operating procedures. Gas insulated circuit breakers are specifically excluded from this survey.