Fault Current Interruption Research Articles

Advanced closing switch for three‐phase short‐circuit test of a very fast current limiter

Advanced closing switch for three-phase short-circuit test was developed for very fast current limiter using power electronics devices. The conventional short-circuit test method was used for verification of the current interrupting device with longer time duration to interrupt fault current after the separation of contacts. In the conventional short-circuit test method, a deviation of the closing time between each phase closing switch with a mechanical driving was regulated so that the breaking performance of the conventional switching device could be examined. However, in the new current limiter with very short fault current interruption time, the deviation time between each phase must be reduced less than the regulated time by the conventional test method. For this purpose, the advanced closing switch for three-phase short-circuit test method was developed. In the advanced test method, power electronics devices were used for the initiation of three-phase short-circuit fault. Results of the short-circuit test showed that the advanced circuit had very small deviation time between the initiation of each phase fault. Also, the very fast current limiter with power electronics devices was shown to have an intended interrupting performance. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 68–75, 2000

Advanced closing switch for three-phase short-circuit test of a very fast current limiter

Advanced closing switch for three-phase short-circuit test was developed for very fast current limiter using power electronics devices. The conventional short-circuit test method was used for verification of the current interrupting device with longer time duration to interrupt fault current after the separation of contacts. In the conventional short-circuit test method, a deviation of the closing time between each phase closing switch with a mechanical driving was regulated so that the breaking performance of the conventional switching device could be examined. However, in the new current limiter with very short fault current interruption time, the deviation time between each phase must be reduced less than the regulated time by the conventional test method. For this purpose, the advanced closing switch for three-phase short-circuit test method was developed. In the advanced test method, power electronics devices were used for the initiation of three-phase short-circuit fault. Results of the short-circuit test showed that the advanced circuit had very small deviation time between the initiation of each phase fault. Also, the very fast current limiter with power electronics devices was shown to have an intended interrupting performance. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 68–75, 2000

Optical-fibre-based investigations of contact travel, gas pressure and particle concentration in SF6 puffer circuit breakers

Experimental results have been obtained about conditions within SF/sub 6/ puffer circuit breakers during and after the interruption of fault currents up to 45 kA peak using optical-fibre sensors based on chromatic modulation. The particular parameters measured with the optical-fibre sensors were the contact travel, the gas pressure in both the puffer piston chamber and the circuit-breaker tank, the radiative emission from the electric arc and the concentration of micron-sized particles produced by the arcing. The experimental results are compared where possible with theoretical calculations from a computational-fluid-dynamics computer package. The possible role of the particulate material in the longer-timescale conditions within the circuit-breaker tank is considered and the need for a better understanding of the particulate-material properties and formation is highlighted.

Numerical analysis of electromagnetic forces in low voltage AC circuit breakers using 3-D finite element method taking into account eddy currents

It is necessary for the optimum design of low voltage circuit breakers to analyze electromagnetic forces acting on the contact systems when the circuit breakers interrupt fault currents. In this paper, the forces which are known as the magnetic blowout force acting on the arc and the electromagnetic repulsion force acting on the moving contact arm are obtained by using the 3-D finite element analysis taking into account eddy currents. It is shown that our 3-D analysis is capable of evaluating a new design of contact systems in low voltage ac switching devices.

3-D finite element analysis of magnetic blowout forces acting on the arc in molded case circuit breakers

It is necessary, for the optimum design of molded case circuit breakers, to analyze magnetic blowout forces acting on the arc in the contact systems when the circuit breakers interrupt fault currents. In this paper, the forces generated by the arc current and the flux density are obtained by using 3-D finite element analysis, taking into account the current distribution in the current paths and variations in arc diameter. It is shown that this 3-D analysis approach is capable of evaluating new designs of contact systems in molded case circuit breakers.

Simulation of gas flow phenomena in high-voltage self-blast circuit breakers at heavy fault current interruption

CFD (computational fluid dynamics) calculations for high- and low-current arcs in an interrupter of the self-blast type have been performed. The high-current simulation provides information about the mixing process of the hot PTFE cloud with the cold SF/sub 6/ which is difficult to access for measurement. In addition, it yields the gas state inside the pressure chamber when the fault current approaches its current zero. Depending on the arcing time, fault current and interrupter geometry blow temperatures of up to 2000 K with a PTFE mass fraction of up to 10% have been found. The low-current simulation performed for this blow temperature gives detailed information about the arc behaviour in the time immediately before current zero. Special attention has been paid to the flow phenomena in the expanding nozzle region. Due to the interaction of the supersonic flow with the obtuse arcing contact and the nozzle geometry, a complex flow structure with a shock Is established. This has been simulated for low-current arcs in an extinguishing flow with boundary conditions as obtained from the high-current simulation.

3-D finite element analysis of repulsion forces on contact systems in low voltage circuit breakers

Low voltage circuit breakers which interrupt fault currents rapidly are widely used in power distribution systems. It is necessary, for the optimum design of circuit breakers, to analyze electromagnetic forces on the contact systems equipped with arc rupturing parts. In this paper, the forces generated by currents and flux densities are obtained by using the 3-D finite element method taking into account current constriction and variations in arc diameter. It is shown that the 3-D analysis is capable of evaluating new designs of LV circuit breaker contact systems.

Ignition of an electrical arc in a capillary: arc parameters in the initial period

Fuse-to-varistor current commutation offers considerable promise for easier and cheaper high fault current interruption in distribution systems. Commutation relies on the fast generation of high voltages by the fuse. The fuse arc ignition period has been examined, with an emphasis on expulsion fuses. In the paper, relationships between the energy of the fuse arc ignition, the arc pressure and the peak voltage are presented and compared with experimental data. It is demonstrated that the actual arc length, energy and pressure are all proportional to each other. The arc length was approximately determined using streak records available in the literature. During the ignition period it was found that the sum of the length of individual arcs increased as a function of the time squared. It was also established that the pressure rise in capillary confinements is due to vaporisation of the fuse element rather than the walls of the enclosure. >

Finite element analysis of fault current interrupter for pad-mounted switchgear package

The author presents the results of a numerical analysis of a magnetic sensor device for a resettable vacuum fault interruption system. It uses a force generated between the connecting bus and a steel element which can drive the trip rod. The force acting on the steel members of the device is generated by the magnetic field around the connecting bus. The field distribution is determined by the finite element method (FEM). Two different configurations of the device are analyzed: with a steel disk and with a U-shaped magnetic circuit. Computational results are compared with experimental data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Resettable economical fault current interrupter for taps of a padmounted switchgear package

A resettable overcurrent protective device has been developed for padmounted switchgear packages. A low-Curie-temperature alloy and permanent magnet latch provide a simple, direct sensing and tripping means. Electromagnetic trip action at high fault currents causes two-cycle interruption to be attainable with the vacuum bottle and spring actuated mechanism. Linkage can be incorporated to provide three-phase tripping with single-phase fault detection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Computer Analysis of Switching Transients Involving ARC Model

The objective of this paper is to study the relevance of computerised modelling technigues to the solution of switching transients involving dynamic arc. The system is to be represented by a set of mathematical equations by the Rung-Kutta-England numerical technique and the nonlinear dynamic arc model is to be used as the circuit element. The work is concerned with the analysis of the transient recovery voltage (TRV) created by th^ cable-connected busbar fault current interruption in distribution system. In this paper, a new analytical method has been developed for solving this problem: the modified DOMMEL method. The TRV in the I.E.C. standards was compared with the more accurate simulation developed in this paper for the case of the cable-connected bus fault. In particular, the wave form of the TRV is similar to that of the short line fault on the transmission line which imposes a severe duty on the circuit breaker due to the high initial rate of rise of the voltage across the circuit breaker. The results indicated large differences and it issuggested that the I.E.C. standard needs modification.

Network equivalents in power system electromagnetic transient analysis

The paper develops an analysis basis and procedure by which parts of a complete network may be represented in equivalent form in evaluations of electromagnetic transient propagation in power systems. In particular, the equivalents are based on impulse driving-point and transfer impedance functions for networks of multi-conductor power transmission lines. The paper shows how these functions may first be defined numerically as discrete time series and then used in over-voltage studies of line energisation within a network, the analysis of the electromagnetic transients of short-circuit fault conditions, and the evaluation of circuit-breaker transient recovery voltages in fault current interruption.

Factors influencing the formation and structure of fuse fulgurites

Cartridge fuselinks rely upon the properties of the arcs initiated after melting to ensure satisfactory interruption of fault currents. Factors which influence the properties of fuse arcs and subsequent formation of ‘fulgurites’ are described in this paper. Attempts are made to include parameters not only attributable to the physics of the arc column itself, but also those having a relationship to the physical properties and geometry of components such as filler, conducting element and cartridge.

Transient torque of turbine‐generator system under sequential three‐phase fault current interruption

Transient torque of turbine‐generator system under sequential three‐phase fault current interruption

A new 115-kv stored-energy-type capacitor switch

SHUNT CAPACITORS for supplying leading reactive kilovars for power-factor correction have been used on power systems for a great many years, but it is only recently that large shunt capacitor banks have been applied extensively to power systems at primary transmission voltages. Such applications have given rise to a requirement for satisfactory high-voltage switching equipment at minimum cost. Up until the present time the power system engineer has had but little choice of equipment other than the standard commercially available power circuit breakers for his capacitor switching applications. Such circuit breakers were designed fundamentally for the relatively infrequent interruption of system fault currents; were very often without special design considerations for interruption of capacitive currents; and were so costly as to restrict definitely the economic feasibility of many potential applications. Conversely, a capacitor switch should be designed to function satisfactorily when subjected to a very large number of routine switching operations, possibly several per day, without frequent maintenance periods; may be designed with relatively low fault-interrupting capacity, as fault protection is usually obtained by individual capacitor fuses and station bus differential; and should be designed for minimum cost to extend the range of economic feasibility of shunt capacitor installations at transmission voltages.

A New 115-Kv Stored-Energy-Type Capacitor Switch [includes discussion

Shunt capacitors for supplying leading reactive for power factor correction have been used on power systems for a great many years, but it is only recently that large shunt capacitor banks have been extensively applied to power systems at primary transmission voltages. Such applications have given rise to a requirement for satisfactory high-voltage switching equipment at minimum cost. Up until the present the power system engineer has had but little choice of equipment other than the standard commercially available power circuit breakers for his capacitor switching applications. Such circuit breakers were fundamentally designed for the relatively infrequent interruption of system fault currents, they were very often without special design considerations for interruption of capacitive currents, and were so costly as definitely to restrict the economic feasibility of many potential applications. Conversely, a capacitor switch should be designed to function satisfactorily when subjected to a very large number of routine switching operations, possibly several per day, without frequent maintenance periods; it may be designed with relatively low fault-interrupting capacity, as fault protection is usually obtained by individual capacitor fuses and station bus differential; and it should be designed for minimum cost to extend the range of economic feasibility of shunt capacitor installations at transmission voltages. Field tests on a prototype of such a switch have now been successfully performed and are outlined in this article.

A 230-Kv 10,000-Megavolt-Ampere Steel-Clad Impulse Breaker - Another Rating in a Line of High-Capacity High-Voltage Breakers [includes discussion

This paper describes a further step in the development of a line of high-voltage high-capacity steel-clad impulse oil circuit breakers to fulfill the industry requirements for increased interrupting ratings at 138 kv, 161 kv, 230 kv, and 330 kv. The 230-kv 10,000-megavolt-ampere breaker introduced in this paper follows the design concepts formulated for the initial step and offers the same excellent operating characteristics associated with the impulse oil-blast principle of interruption. A new tank configuration results in an oil reduction of 40 per cent over the 230-kv conventional round tank breaker while doubling the short-circuit interrupting rating of that design. It further minimizes ground shock disturbance during the interruption of heavy-duty fault currents and allows overall tank heights to be reduced to such an extent that it is now possible to ship 230-kv breakers with all three poles factory-assembled and welded to a unit base. Complete electrical, interrupting, and mechanical design tests demonstrated that the breaker meets all industry standards with ample margins of safety. Tests at the Switchgear Development Laboratory included both fault duty interruptions and the switching of line charging currents. These tests have fully proved the adequacy of the design and indicate that higher interrupting ratings could be obtained, with modifications.

Arcing time of high-voltage air-break contactors

A HIGH-VOLTAGE AIR-BREAK contactor must be able to interrupt the circuit to motor loads or static loads covering a wide current range. Considerable attention has been given to the ability of contactors to interrupt fault currents, but little has been published on the problem of obtaining satisfactory performance at low currents. The difficulty at low currents is one of getting acceptably short arcing time.

Arcing time of high-voltage air-break contactors at low currents

A high-voltage air-break contactor must be able to interrupt the circuit to motor loads or static loads covering a wide current range. Considerable attention has been given to the ability of contactors to interrupt fault currents, but little has been published on the problem of obtaining satisfactory performance at low currents. The difficulty at low currents is one of getting acceptably short arcing time.

Performance Test of the Allgemeine Elektricitats Gesellschaft Free-Jet Air-Blast 220-Kv 2,500-Megavolt-Ampere Reclosing Circuit Breaker

Tests of a representative sample of this circuit breaker were made on the system of the Bonneville Power Administration in order to provide an opportunity for American manufacturers and operating engineers to study the operation of this circuit breaker in interrupting faults and line charging currents. A single pair of interrupting contacts in open air, ease of contacts visual inspection, maintenance and replacement attracted much attention and favorable comment, particularly from operating engineers. The circuit breaker successfully interrupted fault currents in about six cycles (average) as compared with three cycles of fast oil circuit breakers of American manufacture. Interruption of line charging current, although successful, was accompanied by many restrikes. It is hoped that these tests and the analysis of the test data will facilitate development of an American circuit breaker which will retain the favored features of the European prototype but will be faster in interrupting fault currents and practically free from restrikes in interrupting line charging currents.