Oil Circuit Breakers Research Articles

Calculation of electrical energy losses in distribution networks for power supply using oil and vacuum circuit breakers

A method for approximate estimation of load losses in distribution networks from 6 to 10 kV, as well as for lower voltage networks, has been proposed. The main advantage of this method is that the root mean square current is calculated only once for a series of calculations. This approach significantly reduces the time required for calculations and improves their accuracy, as it eliminates the need for multiple determinations of the root mean square current for each individual calculation. The proposed approach contributes to a better understanding of the influence of various factors on load losses, which allows for more effective planning and management of distribution networks. This is particularly important in the context of increasing loads on electrical networks and higher demands for their reliability and efficiency. In the calculation of electrical energy losses in distribution networks from 6 to 10 kV, methods that use generalized coefficients of electrical circuits and operating modes in the form of regression equations are widely applied. The most significant and independent factors, such as the input of active energy, total line length, number of line sections, total number of transformers, and their total installed capacity, must be taken into account and are included in the calculation equation. Additionally, the components used and their regular maintenance play an important role in electrical energy losses in electrical networks. The main direction of research is the optimization of distribution network parameters, taking into account the latest technologies and materials, as well as the implementation of automated monitoring and control systems that will allow timely detection and elimination of problems associated with electrical energy losses. The proposed method for estimating load losses in distribution networks is a promising direction for the development of the energy sector, which will contribute to improving the efficiency and reliability of electrical networks, as well as reducing the costs of their operation and maintenance.

ВЛИЯНИЕ ХИМИЧЕСКОГО СОСТАВА ТРАНСФОРМАТОРНОГО МАСЛА НА ЕГО ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

Transformer oils are used to fill power and measuring transformers, reactor equipment and oil circuit breakers. Depending on the origin of the oil from which transformer oils are produced, as well as the production technology, the physical and chemical properties of oils may differ significantly, which affects their operational properties. These differences are a consequence of a significant difference in their structural group composition, as well as different molecular composition within the structural groups, which leads to different behaviour of oils in the process of degradation. The article considers the peculiarities of technological production and raw materials used in the manufacture of the most widely spread transformer oils, as well as the processes of their degradation. The analysis of literature data showed a significant difference in the chemical composition of transformer oils depending on the origin of oil and production technologies. The aim of the work is to establish the relationship between the chemical composition of transformer oil samples and their technical characteristics. The paper presents the results of the study of structural and group composition of transformer oil of different grades (GK, VG, T-1500, TKp, Nytro) by spectroscopy in the visible and near infrared spectral region. On the basis of the analysis of literature data and conducted research, the dependence of oil stability (oxidation stability) on the concentration of aromatic hydrocarbons was established, namely, the higher the concentration of aromatic hydrocarbons, the lower the stability of oils, which is confirmed by spectral measurements of oils. This method of analysing transformer oil samples allows to determine its structural-group composition and estimate the depth of purification, which is valuable information for the possibility of mixing oils in combination with mandatory types of tests.

Performance analysis of protection devices in electrical power distribution system: Eko Electricity Distribution Company as a case study

One of the major challenges hindering the effective operation of the electricity distribution system is the malfunctioning of the protection scheme. Therefore, in this study, the performance of an interrupter (oil circuit breaker (OCB)) on the Eko Electricity Distribution Company (EKEDC) network was assessed. Five-year outage data (2014 to 2018) regarding tripping of the interrupter on fault and health conditions were collected from the EKEDC Agbara/Badagry Business Unit. The tripping frequency was compared. Inspection of selected OCBs within the considered network was conducted over the study period. A breakdown voltage (BDV) test was carried out on six oil samples each for 11 and 33 kV OCB using Megger OTS60PB. The highest tripping frequency of 75 and 10 were observed in 2014 and 2018 respectively when the interrupter tripped on fault and healthy conditions. The lowest tripping frequency was, however, observed in 2018 with values of 46 and 7 respectively when the interrupter tripped on fault and healthy conditions. The inspection conducted revealed carbonized OCB contacts. The BDV test showed that two oil samples each violated the standard value of 40 kV for 11 and 33 kV OCBs respectively. This study indicated that the defective oil samples required filtration or complete replacement.

Influence of Mineral Oil-Based Nanofluids on the Temperature Distribution and Generated Heat Energy Inside Minimum Oil Circuit Breaker in Making Process.

The enhancement of the thermal properties of insulating oils has positively reflected on the performance of the electrical equipment that contains these oils. Nanomaterial science plays an influential role in enhancing the different properties of liquids, especially insulating oils. Although a minimum oil circuit breaker (MOCB) is one of the oldest circuit breakers in the electrical network, improving the insulating oil properties develops its performance to overcome some of its troubles. In this paper, 66 kV MOCB is modeled by COMSOL Multiphysics software. The internal temperature and the internally generated heat energy inside the MOCB during the making process of its contacts are simulated at different positions of the movable contact. This simulation is introduced for different modified insulating oils (mineral oil and synthetic ester oil) with different types of nanoparticles at different concentrations (0.0, 0.0025, 0.005, and 0.01 wt%). From the obtained results, it is noticed that the thermal stress on the MOCB can be reduced by the use of high thermal conductivity insulating oils. Nano/insulating oils decrease internal temperature and generate heat energy inside the MOCB by about 17.5%. The corresponding physical mechanisms are clarified considering the thermophoresis effect.

Analysis of Oil Dielectric Strength Insulation on Oil Circuit Breakers Based on Service Life and Operating Frequency

The electricity distribution breakdown can be caused the service life and operating frequency of Oil Dielectric Strength (ODS). Hence, it requires a study due to the spare part is difficult to find. This paper aims to test the ODS on Oil Circuit Breaker (OCB) of 13.8 kV aged between 29 to 43 years. The test used the ASTM D1816 standard to analyze the effect of oil life and circuit breaker operating frequency on the physical, color and strength of ODS. For the visual test used the ASTM D1524 standard. The color test based on the ASTM D1500 standard. From the test results, it can be seen that 6DN F1 was yellow-black in colors. The color level was from 0.5 to 6, which was a striking color difference. This happens because it had been operating for 3 years with a frequency of 2 manual open times and 11 trips with a large normal load of 206A. In the 8D F7 feeder, there was also a decrease in breakdown voltage, which was far from 45.6 kV to 9.7 kV. Therefore, the oil was declared failed due to below the minimum standard of 27 kV. Based the validity test, the six samples were still within the allowable limits based on ASTM D1816 with the range value being below 92%. This means that the six samples were valid.

ВЛИЯНИЕ ОСТАТОЧНОЙ НАМАГНИЧЕННОСТИ СЕРДЕЧНИКОВ ТРАНСФОРМАТОРОВ ТОКА НА СООТВЕТСТВИЕ ИХ ТЕХНИЧЕСКИХ ХАРАКТЕРИСТИК ТРЕБОВАНИЯМ МИКРОПРОЦЕССОРНЫХ УСТРОЙСТВ РЕЛЕЙНОЙ ЗАЩИТЫ

Work objective is finding rational technical and economic solutions for examining current transformers for techspecs compliance satisfying the requirements of reinstalled microprocessor type protective relays and automation devices manufactured by NP EKRA LLC, taking into account DC component. Research methods: analytical methods for calculating the time of remnant magnetization in the core of a current transformer. Research results and novelty: it is understood that the saturation time of current transformers of the basic and backup protections, according to the results of the analytical method, was more than 25 ms, and for current transformers of differential bus bar protection was more than 5 ms. The obtained saturation time values for all types of current transformers built into oil circuit-breaker bushings (HV line) of 110 kV and bus bar coupling connector (BCC) of 110 kV (main protection, backup protection, differential bus protection), both in the absence and in the presence of remanent induction magnetic in CT cores with three-phase and single-phase short circuits, satisfy completely technical requirements either of microprocessor type protective relays or CT differential bus bar protection. Conclusion: built into CT BCC circuit-breaker bushings of 110 kV and oil circuit-breaker bushings (HV line) of 110 kV Foundry substations do not necessitate a mandatory replacement in case of non-complex redesign of microprocessor type protective relays and automation devices. When replacing oil circuit breakers with gas-insulated ones, it is recommended to use CT with similar characteristics.

Operation of Circuit Breakers: Data and Analysis

An attempt has been made for the analysis on Circuit breakers (CBs) this paper. First, the types and arcing phenomenon of Oil and SF6 Circuit breakers were briefly discussed. However, various CBs were analyzed in terms of certain outage frequencies and reliability indices to ascertain the most reliable CB. This was possible using data collected from the 33kV Transmission Company of Nigeria (TCN) New Haven, Enugu. After the analysis, Emene Industrial CB had the highest value of availability of 0.9999 and the lowest tripping report while Ezillo had the highest failure rate of 0.1032.

REDUCTION OF ENERGY LOSSES ON HEATING OIL CIRCUIT BREAKERS 35–110 KV IN JSC «CHERNIGIVOBLENREGO»

The analysis of the state of 35–110 kV circuit breakers in the Chernihiv region, which are on the balance sheet of the operator of the distribution system JSC «Chernigivoblenergo», has been carried out. It was shown that the number of circuit breakers that satisfy regulatory documents is only 18.9 % in 35 kV and 2 % in 110 kV power networks. Unfortunately, most of the 35–110 kV circuit breakers in the Chernihiv region are low-oil and bulk-oil type, which required heating during cold meteorological conditions. The article assess the duration of the circuit breakers heating and their drives, depending on the selected set point of the temperature and the averaging interval of the ambient temperature, and the value of technological energy losses. The article considers following ways to reduce technological costs for heating: optimization of the heating control system, replacement of oil circuit breakers with modern vacuum and SF6 circuit breakers, which require lower costs on heating, and applied both above ways. The effectiveness of the above ways was done with apply Net Present Value, which includes not only investments and Net Profit Margin, but also operating costs and Discount Rates. It has been shown that all of the above ways are effective. In particular, the least costly is the modernization of the heating control system, which has payback period is low three years. The payback period for second way to replace all 35–110 kV oil circuit breakers with modern ones at JSC «Chernigivoblenrego» is about 6.5 years, but this way requires large investments. However, this way cannot be done in one year. Therefore effectiveness will be less due to energy losses to operated oil circuit breakers.

Особливості експлуатації високовольтних електричних вимикачів

The paper draws attention to the fact that nowadays there are many high-voltage switches in operation of different manufacturers and designs, which differ in arc-quenching environment, principle of operation, features of operation. This requires from the maintenance and repair staff additional knowledge and skills agreed with the representatives of enterprises - manufacturers of switches of new designs. Based on the analysis of the statistics of damage to high-altitude switches, it is proved that there is not only damage to obsolete oil or air switches, but also new SF6 switches. the number of damaged SF6 circuit breakers in the total number of damaged high-voltage circuit breakers is 7.1%, while air circuit breakers - 22.3%, and oil circuit breakers - 70.6%. In order to improve the quality of operation of high-voltage switchgear equipment, it is necessary to have information about the technical, preferably current, condition of high-voltage switches. After all, these switches, by disconnecting damaged electrical equipment, significantly reduce the time of leakage of short-circuit overcurrents, and therefore reduce the likelihood of spreading damage to adjacent to the damaged equipment. To reduce errors of the first and second kind when forming conclusions about the technical condition of the diagnosed switch, it is desirable to use modern methods and tools of diagnosis. Conclusions based on the results of diagnosing circuit breakers should take into account the determination of risks during operation of the diagnosed circuit breakers. The following risk components are considered in the article: risk component of damage to living beings as a result of electric shock as a result of non-operation or destruction of the switch; component of the risk of physical damage to high-voltage equipment adjacent to the switch caused by failure of the switch, which could lead to explosion or fire, leakage of SF6 and endanger the environment, component of the risk of failure of internal switch systems due to deterioration main contacts, reduction of SF6 pressure, etc.) during switching on / off of rated currents; components of risk for electrical equipment of the switchgear in case of short circuit near the switchgear, component of risk of failure of internal circuit breaker systems caused by disconnection of short-circuit currents in the cycle of unsuccessful APV; Risk components for switchgear and switchgear equipment in the event of a short circuit in or near switchgear equipment, namely: component of risk of damage to living beings due to electric shock or step voltage during short circuits in switchgear equipment and switch failure , component of risk of physical damage to switchgear equipment (fire or explosion caused by short circuits and overloads of electrical equipment of switchgear and failure of appropriate switches due to unsatisfactory technical condition of the switch; component of risk of failure of the switch caused by damage to the source coil on and off coils, risk components for the circuit breaker during a short circuit in the operating DC line, namely the component of the risk of failure of internal circuit breaker systems caused by breakage or short circuit in the operating DC or voltage lines.

A review study on various types of circuit breaker and its application

The generation, transmission, distribution, and substation are all parts of the power system. All power system components need appropriate protection devices as part of the protection system to safeguard the system in the event of a failure. The circuit breaker has been chosen as one of the protective devices in many applications in this article. Oil circuit breakers (OCB), air circuit breakers (ACB), sulphur hexafluoride (SF6) circuit breakers, vacuum circuit breakers, and DC breakers (hybrid DC breaker and solid-state DC breaker) are among the circuit breakers discussed in this article. Normally, the failure disrupts or damages the systems or circuits. The kind of faults and causes of faults must be understood in order to install a protective system in the system or circuit. The substation is required to regulate the voltage transferred at high voltage from the producing station in order to deliver the appropriate voltage to the consumer. A substation must also include a protection system.

Инновационная технология рентгенографического контроля технического состояния высоковольтных выключателей в эксплуатации

The paper displays the results of the practical application of an instrumentation and analytical system (IAS) for X-ray control of minimum oil and SF6 circuit breakers. The capabilities of IAS are described and the technology for its implementation is given. The paper shows that the proposed technology makes it possible to control the contact group (moving and fixed contacts) and elements of the moving contact control system of circuit breakers without bus bar dismantling, oil drain, and disassembly of the circuit breaker poles. The paper also presents the assessment of the reliability indicators of high-voltage circuit breakers, which confirms the prospects for introducing the developed X-ray control technology.

X-ray testing of high voltage oil-filled electrical equipment: Physical background and technical requirements

In this study the capability of X-ray technology to examine the internal elements of high-voltage equipment is reported for the first time. Samples of high-voltage minimum oil and SF6 circuit breakers were designed and tested to evaluate the X-ray images and compare with known artificial defects. The assessment of the influence of X-ray spectral energy characteristics on information obtained by X-ray imaging of objects having spread equivalent radiation thickness determined the technical requirements for this analysis.

Innovative X-ray control technology of high-voltage circuit breaker technical condition

The paper presents the results of practical application of an instrumentation and analytical system (IAS) for X-ray control of minimum oil and SF6 circuit breakers. The capabilities of IAS are described and the technology for its implementation is given. It is shown that the proposed technology makes it possible to control the contact group (moving and fixed contacts) and elements of the moving contact control system of circuit breakers without bus bar dismantling, oil drain and disassembly of the circuit breaker poles. The paper also presents the assessment of the reliability indicators of high-voltage circuit breakers, which confirms the prospects for introducing the developed X-ray inspection technology.

Генераторные выключатели для атомных электростанций

A comparative analysis of the characteristics of foreign and domestic generator circuit breakers is carried out. The necessity of developing a domestic generator circuit breaker for newly constructed nuclear power plants with a power unit capacity of over 1200 MW is shown. The most promising solution is the development of hybrid generator circuit breakers using main contacts, vacuum circuit breakers and controlled arresters. The scheme and operation of elements of hybrid circuit breakers in modes of shutdown of three
phase short
circuit current is resulted. The developed mathematical model of hybrid breakers consisting of generator, busbar and transformer for power plant and given transients disable the short
circuit current in different modes. It is proposed to develop hybrid circuit breakers to replace oil and air circuit breakers at the stages of modernization of nuclear power plants, and in the new construction it is advisable to use generator circuit breakers, as a prototype of which the gas-insulated device developed by ABB is given. Basic electrical formulas for estimation of the switching capacity of the circuit breaker of the generator in the amplitude of the current gap three
phase short
circuit current, degree of asymmetry, amplitude and rate of rise of transient recovery voltage formulated.&nbsp

Evolving Fault and Parallel Switching for SF6 Circuit Breakers

A special stress for circuit breaker is the occurrence of evolving fault or parallel switching condition. These switching cases are not standardized by international standards, but may occur in service and may create problems for the breaker. In the past, it was a problem mainly with oil circuit breakers and some types of air-blast circuit breakers but lesser known with SF6 circuit breakers. In the meantime, with upcoming new switching technologies along with changed operating duties, some doubts exist that these switching cases may become an issue again. This paper explains in detail the background of these stresses and presents a method to evaluate the capability of SF6 circuit breakers for such situations. The theoretical evaluation involves network calculations, gas flow simulations, and dynamic dielectric analysis. It is important to note here that several tests have been done in the past for evolving and parallel switching faults for both puffer as well as self-blast circuit breakers with the knowledge available at that time. These test results are used to validate the outcome of the theoretical evaluation which will help in better prediction of the circuit breaker behavior before performing actual tests. It can be concluded that theoretical simulation may, in majority of the cases, serve as sufficient proof to show feasibility for such cases.

Metodologija za određivanje vremena zamene prekidača na bazi pouzdanosti i integrisanog faktora rizika

In this paper, new methodology for circuit breaker (CB) replacement time is introduced. Method is based on statistical analysis of gathered data from CB's exploitation, and on the influence of CB replacement on power stations reliability. Economical influence of CB replacement on power stations reliability is also analyzed with costs of each action. Gathered data covers 427 minimum oil CB's of 35kV and 10kV from period of 10 years. Voltage drop values from all CB's were analyzed using Weibull probability distribution and power stations reliability is determined by minimal path and minimal cut methods. That way, influence of CB's condition on power stations reliability is assessed. Example of this method is shown on 35/10kV power station. Power stations reliability is analyzed through 5 different scenarios of CB's replacement, with cost of each action. At the end, discounted costs of future investments for each action are calculated. For the power station in this example results are showing best scenario with power transformers CB's replacement.

Oil Circuit Breakers: A Look at the Earlier Generation [History

In the late 19th and early 20th centuries, the interrupting media of circuit breakers were either air, oil, or water. Figure 1 depicts a collection of breakers of that vintage. The breaker shown in Figure 2 was for application at 40 kV, installed in 1901, and consisted of two barrels half-filled with water for performing interruption and oil in the upper section to provide open position dielectric. This performed fairly well until several operations were made over a short time, and it exploded, destroying the adjacent power house. Figure 3 is an oil circuit breaker (OCB) that was originally on the western Colorado power system at a voltage of 44 kV and in service for 52 years; it consisted of two barrels of oil with the interrupters and a movable current-carrying member between them.

On issue of reconstruction at central distribution substation by example of one of plants of Chelyabinsk region

The article considers the issues of increasing the reliability and economy of the distribution substation. The result is found due to the reconstruction of the central distribution substation and one of the plants of Chelyabinsk region. The reasons for the reconstruction are explained. A comparison of oil and vacuum circuit breakers is made. The advantages of vacuum circuit breakers are shown. Alternative replacement of cables is offered. The basic technical characteristics of the cable brands are shown. The results of reconstruction are proved.

Types of Circuit Breaker and its Application in Substation Protection

Power system consists of the generation, transmission, distribution, and substation. All the power system component requires suitable protection devices as the protection system to protect the system during fault occur. In this paper, the circuit breaker has been selected as one of the protection devices in several applications. The types of circuit breaker that has been reviewed in this paper are oil circuit breaker (OCB), air circuit breaker (ACB), sulphur hexafluoride (SF6) circuit breaker, vacuum circuit breaker, and DC breaker which are hybrid DC breaker and solid-state DC breaker. Normally, the systems or the circuits disrupted or damaged by the fault. To implement the protection system in the system or circuit, the type of faults and cause of faults should be known to overcome the fault. To provide the suitable voltage for the consumer, the substation is needed to control the voltage transmitted at high voltage from the generating station. Protection system is also required in a substation.

Расчет переходных восстанавливающихся напряжений при выборе выключателей для электроустановок напряжением 110 кВ и выше

In clearing short-circuit faults, a transient recovery voltage (TRV) arises between the circuit breaker contacts, which may initiate repeated ignition of electric arc. For modern circuit breakers, including SF6 and vacuum ones, the maximum permissible TRV peak and rate of rise values are given in the GOST(State Standard) R 52565-2006. Earlier editions of the relevant standards contained the requirements only for air blast and oil circuit breakers. The use of modern electrical installations with circuit breakers selected without paying proper attention to TRV may lead to accidents with severe consequences. The article presents a theoretical and calculated comparison of the regulatory documents applicable to circuit breakers for rated voltages of 110 kV and higher and contains recommendations on calculating the TRV parameters that can be used as reference ones in checking the breaking capacity of high-voltage circuit breakers. Methods for calculating the parameters of TRVs with exponential, single-frequency and sawtooth waveforms are considered and compared with one another. Examples of calculating transients involving different TRV waveforms are given. The necessity of calculating TRV with a sawtooth waveform for SF6 and vacuum circuit breakers is pointed out. For updating the design conditions under which the maximum TRV rate of rise and peak values may occur, it is recommended to continue the study. In particular, it is advisable to determine the critical remoteness of a short circuit fault on the line side determined by the combined effect of power line parameters and short-circuit current values on the TRV.