Earthing Switch Research Articles

Development of a Generalized Scaled-Down Realistic Substation Laboratory Model for Smart Grid Research and Education

This paper introduces a physical scaled-down realistic substation laboratory model development for translational research and education in smart grids. The development of a substation panel with four 3-<inline-formula> <tex-math notation="LaTeX">$\phi $ </tex-math></inline-formula> feeders of 415 V, 65 A rating is described in detail. The developed substation model can be configured to realize seven widely used substation bus bar arrangements. A programmable logic controller (PLC) is used to create interlock mechanisms for mimicking the actual substation operation practices. Provision is made to realize the gang and independent pole operation of circuit breakers, the manual and remote modes of operation, and different types of current transformer arrangements. The substation panel can host up to 10 commercial IEDs, and multiple substation panels can be cascaded to form a bigger station using the master-slave configuration of PLCs. All the potential transformer and current transformer measurements, circuit breaker, isolator, and earth switch status signals are made available for connecting field devices. The developed substation model can be used for advanced research on substation automation using IEC61850, validation of new protection strategies, implementation and testing of new algorithms (such as topology processing, state estimation) for energy management systems (EMS) like how they get implemented in the field.

Ensuring electrical safety of power supply systems of electrified AC railways for highspeed lines

Abstract. High-speed railways are fast-growing and promising type of traffic. In Russia development of high-speed railway service is associated with the solution of a number of problems, including infrastructure. Authors propose to use earth connection of the railway catenary with the help of an artificial earthing switch on currently designed high-speed line Moscow—Kazan for 2×25 kV power supply system. Taking into account requirements for electrical safety conditions for maintenance of the track and earthed catenary supports, paper justifies method for calculating allowable voltages of rail—earth points and supports of catenary. Methods takes into account structural features of ballastless track superstructure used for high-speed lines. It is estimated that the voltages admissible under the electrical safety conditions are random in nature and distributed logarithmically normal. When calculating probability of safe operation, one should take into account random nature of both permissible stresses and those actually occurring on the track. It is estimated that the probability of safe operation in traction networks of sections with ballastless track superstructure does not exceed a similar value in electrified sections with the conventional structure of a ballast prism. Feasibility of using a 2×25 kV earth system using an artificial earth connection is confirmed, recommendations on its use are given. Authors substantiate allowable values of the rail—earth voltage and catenary supports, which practically exclude the occurrence of hazardous situations for personnel maintaining the track in sections with ballastless track superstructure.

------------ -3 (Methodical Instructions to Perform the Calculation and Graphical Work on the TOE-3 Calculation of the Electric Field and the Main Parameters of the Cylindrical Electric Earthing Switch)

------------ -3 (Methodical Instructions to Perform the Calculation and Graphical Work on the TOE-3 Calculation of the Electric Field and the Main Parameters of the Cylindrical Electric Earthing Switch)

Pre-Arcing Time Prediction in a Making Test for a 420 kV 63 kA High-Speed Earthing Switch

A high-speed earthing switch (HSES) of a gas-insulated switchgear (GIS) performs a secondary role in protecting the power system in the event of an accident. After being interrupted by a circuit breaker (CB), the short-circuit current remaining in the network should be earthed by the HSES. However, as the contacts of the HSES may have been damaged by a pre-arc during the closing operation, the HSES may fail to ground the short-circuit current. To successfully ground the short-circuit current, the contacts of the HSES must be protected from damage by the pre-arc. Thus, minimizing the pre-arcing time is required to step up the making performance. This paper analyzes the making performance of the HSES by predicting the pre-arcing time within the short-circuit current making test. To estimate the pre-arcing time, we compared the results of analytical calculations based on streamer discharge theory and the numerical simulations of the electric field strength. By conducting a short-circuit current making test for a 420 kV 63 kA HSES in a high-power laboratory, the pre-arcing time calculation results were verified. A comparison of the results showed that the proposed prediction method was useful for verifying the performance of the HSES.

About how to Optimize Earthing Switch Circuit Bar

This article analyzes the circuit bar of EarthingSwitch (ES), identify the function of grounding system, clarify the different function between grounding system and rated current path. It provides an efficient method to design circuit bar for grounding system. The article collects the practical formula to design and to evaluate Copper bar. The recommended size for the ES and main grounding bar is referable for electric company.

Analytical and Experimental Studies on Induced Current Switching by a Fault-Proof Gas Insulated Earthing Switch

Fault-proof earthing switches are one of the important modules of a gas insulated substation, as it enables make at 100 percent short circuit current, which is functionally different from maintenance earthing switches. The fault-proof earthing switch shall be designed to make and break electro-magnetically and electro-statically induced currents as per IEC-62271-102. The paper discusses the impact of “test circuit configurations and voltage” on test parameters for gas insulated fault-proof earthing switch utilizing simulation with PSCAD software. Authors record the development of a 145 kV gas insulated fault proof earthing switch by considering novel design features like minimum arcing/pre-arcing time, effective current transfer from arcing contact to ground terminal, etc. The development has been evaluated successfully for electro-magnetically and electro-statically induced current duties as per IEC. Finally, design parameters to be considered for ensuring reliable performance during induced current switching from fault-proof earthing switches are also discussed.

Development of insulation technology in compact SF6 gas‐filled bushings: Development of compact 800‐kV SF6 gas‐filled bushings

AbstractEfforts of designers of gas‐insulated switchgear (GIS) are currently focused on such features as smaller installation area and economical efficiency. Circuit breakers (CB), disconnecting switches (DS), and earthing switches (ES) have been redesigned in more compact configurations. Compactness and light‐weight requirements are applied also to bushings used in GIS. GIS bushings can be divided in three general types: capacitor, gas‐filled, and molded bushings. Requirements of the light weight and the economical efficiency of gas‐filled bushings can be satisfied by improvements in insulation technology. Size reduction can be effectively achieved by moderation of the electric field strength on the outside surface of the hollow insulator in the area of the inner grounded electrode tip. We devised a new inner grounded electrode structure consisting of a cylindrical electrode and a ring electrode supported by column electrodes. This paper describes the effect of reduction of the maximum value of electric field strength on the outside surface of the hollow insulator by a new type of grounded electrode. Then, improvement of insulation performance for electrodes with insulation coating in SF6 gas is described as the composite insulation technology. Finally, the efficiency of these insulation technologies is described by the basic insulation test results of a prototype compact 800‐kV SF6 gas‐filled bushing. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 19–27, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20898

Development of SF6 Gas Insulated Disconnecting Switch with Spiral Electrodes using Motor Operating Mechanism

Gas insulated switchgear (GIS) have been demanded reliability and economical efficiency. Circuit breaker (CB), disconnecting switch (DS), and earthing switch (ES) have been designed toward compactness. DS is required the performance of insulation and current interruption. The bus-transfer current is the highest among all current interruption requirements for the DS. To develop an alternating current DS with the low speed driven, it is necessary to reduce the electrode damage. This paper describes the fundamental characteristics of current interruption in the magnetically driven arc using spiral electrode. Since the arc is rotated by magnetically force, the arcing time with spiral electrode is shortened to about 1/3 compared with that of plain break electrode. The DS by magnetically driven arc was confirmed to comply with bus-transfer current switching requirements on JEC standard. Moreover, the physical model of the magnetic driven arc was constructed, and the behavior of the arc could be evaluated quantitatively. As a result, performance of current interruption became to be predictable.

Technical requirements for UHV substation equipment

AbstractCIGRE Study Committee A3 established WG A3.22 ‘Technical requirements for substation equipment exceeding 800 kV’ to review the state‐of‐the‐art technical specifications for substation equipment exceeding 800kV in accordance with a request from IEC SC 17A. WG A3.22 conducted the initial surveys and submitted the first Technical Brochure on technical specifications for substation equipment such as gas circuit breaker (GCB), disconnecting switches (DS), earthing switches (ES), high‐speed grounding switches (HSGS) and metal oxide surge arrester (MOSA) applied to 800 kV and 1100/1200 kV networks. The investigations include the insulation level, first‐pole‐to‐clear factor, DC time constants, transient recovery voltage (TRV), line surge impedance and secondary arc extinction time. WG A3.22 will provide the technical background of all aspects of the available specifications with the intention of identifying the best practice for ultra high voltage (UHV) transmission systems. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Circuit models of gas insulated switchgear elements for electromagnetic wave leakage analysis

The leakage of electromagnetic waves and high frequency surges caused by the partial discharge inside gas insulated switchgear (GIS) to the outside of its tank may become a signal for the partial discharge detection, and, on the other hand, possibly cause electromagnetic interference (EMI) to electronic equipment via the grounded system. It is, therefore, important to investigate and understand the leakage phenomenon of electromagnetic waves and high frequency surges to the grounded system of the GIS. In the present study, experiments of the characteristics of leaking electromagnetic waves and high frequency surges were conducted using test models for the cable connections, the disconnecting switch (DS), the earth switch (ES), the capacity type potential divider (PD) inside the GIS, and the grounding wire to clarify the characteristics of the respective elements. These results could be approximated using distributed parameter circuits, and models for the leakage surge analysis were proposed.

Development of Insulation Technology in Compact SF6 Gas-filled Bushings-Development of Compact 800kV SF6 Gas-filled Bushings-

As for gas insulated switchgear (GIS), small space requirement and economical efficiency have been demanded. Circuit breakers (CB), disconnecting switches (DS) and earthing switches (ES) have been designed toward compactness. Compact & light bushings have been also required. As for bushings of GIS, there are roughly three types; capacitor, gas-filled and molding bushings. Since gas-filled bushings have the feature which is both of the lightness and the economical efficiency, it is important to develop compact and light gas-filled bushings by improvement of insulation technology. The main subject for compact design is reduction of electric field strength on the outside hollow insulator around the inside grounded electrode tip. We devised a new inner grounded electrode structure which consists of some column electrodes. This paper describes the effect of reduction of maximum value of electric field strength on the outside hollow insulator by a new inner grounded electrode. Then, improvement of insulation performance for electrodes with insulation coating in SF6 gas is described as composite insulation technology. Finally, the efficacy of these insulation technologies is described by fundamental insulation test results of prototype compact 800kV SF6 gas-filled bushing.

Fundamental insulation characteristics of air; N2, CO2, N2/O2, and SF6/N2 mixed gases

SF6 gas has excellent dielectric strength and interruption performance. For these reasons, it has been widely used for gas-insulated switchgear (GIS). However, use of SF6 gas has become regulated under agreements set at the 1997 COP3. Presently, development of a gas circuit breaker (GCB) using CO2 gas and development of a high-voltage vacuum circuit breaker (VCB) are being pursued. GIS consists of disconnectors (DS), earthing switches (ES), and buses (BUS) in addition to GCB. Since the interruption performance is not an important requirement for DS, ES, and BUS, use of a gas with high dielectric strength is better than use of a gas with good interruption performance. Air and N2 are not greenhouse gases, and their dielectric strengths are higher than those of other SF6 alternative gases, but only about one-third of the dielectric strength of SF6 gas. This paper deals with a suitable insulation gas which has no greenhouse effect as an SF6 alternative gas. The N2/O2 mixed gas was investigated by changing the ratio of O2. Moreover, the effect of an insulation coating was investigated and compared with the dielectric strength of SF6/N2 mixed gas. The dielectric strength of air under the coating condition was equal to that of 10% SF6/N2 mixed gas. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 9–17, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20348

A high-speed earthing switch in gas-insulated metal enclosed switchgear

A high-speed earthing switch in gas-insulated metal enclosed switchgear

High-Speed Earthing Switch in Gasinsulated Metal-Enclosed Switchgear

A high-speed earthing switch (HSES) can be permanently installed in the switching apparatus in gas-insulated metal-enclosed switchgear (GIS). A new spring-drive driven HSES has been developed and tested in one-phase and three-phase synthetic test circuits. The USES rated voltages, 245 kV and 300 kV, enabled closing (making) operation on the peak value of short-circuit current of 100 kA two times without maintenance, was used. This article presents the main task of HSES at application in GIS, design characteristics, and two different test procedures. Wide searching throughout standards was performed in order to define the real status of this apparatus.

A 40 kV high-power earthing switch

A high-power earthing switch suitable for use in a high-voltage laboratory has been designed, built, tested and is in operation. The design and operation of the switch is presented. It is shown that the system is free of partial discharges, at the highest operating voltage of 40 kV. The operation of the earthing switch is discussed with reference to safety of personnel and short circuit protection. Its compact size and reliability for fail safe operation over an extended period is also discussed. Its function is discussed with reference to circuit layout.

Current interruption by disconnecting switch and earthing switch in GIS

Disconnecting switches (DS) and earthing switches (ES) in gas insulated substations (GIS) can be required to interrupt high currents, which are closed-loop currents for DS and electromagnetic induced current for ES.DS and ES must also have full dielectric strength, even after interrupting these high currents many times. An investigation of the interrupting capability of five types of extinction chambers has revealed that magnetic driving types are optimum for closed-loop current interruption and suction types are optimum for electromagnetic induced current interruption because of their simple construction and excellent performance