WO1998027635A1 - Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation - Google Patents
Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation Download PDFInfo
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- WO1998027635A1 WO1998027635A1 PCT/SE1997/000881 SE9700881W WO9827635A1 WO 1998027635 A1 WO1998027635 A1 WO 1998027635A1 SE 9700881 W SE9700881 W SE 9700881W WO 9827635 A1 WO9827635 A1 WO 9827635A1
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- arrangement
- overcurrent
- switch
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F3/00—Cores, Yokes, or armatures
- H01F3/10—Composite arrangements of magnetic circuits
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/288—Shielding
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/32—Insulating of coils, windings, or parts thereof
- H01F27/323—Insulation between winding turns, between winding layers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F29/00—Variable transformers or inductances not covered by group H01F21/00
- H01F29/14—Variable transformers or inductances not covered by group H01F21/00 with variable magnetic bias
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F3/00—Cores, Yokes, or armatures
- H01F3/10—Composite arrangements of magnetic circuits
- H01F3/14—Constrictions; Gaps, e.g. air-gaps
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
- H02H3/023—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order by short-circuiting
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/025—Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/32—Insulating of coils, windings, or parts thereof
- H01F2027/329—Insulation with semiconducting layer, e.g. to reduce corona effect
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/023—Current limitation using superconducting elements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/028—Current limitation by detuning a series resonant circuit
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2203/00—Specific aspects not provided for in the other groups of this subclass relating to the windings
- H02K2203/15—Machines characterised by cable windings, e.g. high-voltage cables, ribbon cables
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Definitions
- Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation.
- Device and method relatxng to protection of an object against over-currents comprising over-current reduction and current limitation.
- This invention is related to a device in an electric power plant for protection of an object connected to an electric power network or another equipment in the electric power plant from fault-related over-currents, the device comprising a switching device in a line between the object and the network/equipment .
- the invention includes a method for protecting the object from over- currents .
- the electric object in question is preferably formed by a rotating electric machine having a magnetic circuit, for instance a generator, motor (both synchronous and as n- chronous motors are included) or synchronous compensator requiring protection against fault-related over-currents, i.e. in practice short-circuit currents.
- a rotating electric machine having a magnetic circuit, for instance a generator, motor (both synchronous and as n- chronous motors are included) or synchronous compensator requiring protection against fault-related over-currents, i.e. in practice short-circuit currents.
- the structure of the rotating electric machine may be based upon conventional as well as non-conventional technique.
- the present invention is intended to be applied in connection with medium or high voltage.
- medium voltage refers to 1-72,5 kV whereas high voltage is >72,5 kV.
- transmission, sub-transmission and distribution levels are included.
- a conventional circuit-breaker switching device of such a design that it provides galvanic separation on breaking. Since this circuit breaker must be designed to be able to break very high currents and voltages, it will obtain a comparatively bulky design with large inertia, which reflects itself in a comparatively long break-time.
- the over-current primarily intended is the short-circuit current occurring in connection with the protected object, for instance as a consequence of faults in the electric insulation system of the protected object.
- Such faults means that the fault current ( short-circuit current ) of the external network/equipment will tend to flow through the arc created in the object.
- the result may be a very large breakdown.
- the dimensioning short-circuit current/fault-current is 63 kA. In reality, the short- circuit current may amount to 40-50 kA.
- a problem with said circuit-breaker is the long-break time thereof.
- the dimensioning break-time (IEC-norm) for completely accomplished breaking is 150 milliseconds (ms). It is associated to difficulties to reduce this break-time to less than 50-130 ms depending upon the actual case. The consequence thereof is that when there is a fault in the protected object, a very high current will flow through the same during the entire time required for actuating the circuit-breaker to break. During this time the full fault current of the external power network involves a considerable load on the protected object.
- a short-circuit current (fault current) in the protected object may be composed of the own contribution of the object to the fault current and the current addition emanating from the network/equipment.
- the own contribution of the object to the fault current is not influenced by the functioning of the circuit-breaker but the contribution to the fault current from the network/equipment depends upon the operation of the circuit breaker.
- the requirement for constructing the protected object so that it may withstand a high short-circuit current/fault current during a considerable time period means substantial disadvantages in the form of more expensive design and reduced performance.
- the rotating electric machines intended here comprise synchronous machines mainly used as generators for connection to distribution and transmission networks collectively denoted power networks hereunder.
- the synchronous machines are also used as motors and for phase compensation and voltage regulation, then as mechanically idling machines.
- the technical field also comprises double-fed machines, asynchronous converter cascades, external pole machines and synchronous flux machines.
- the magnetic circuit referred to in this context may be air-wound but may also comprise a magnetic core of laminated, normal or oriented, sheet or other, for example amorphous or powder based, material, or any other action for the purpose of allowing an alternating flux, a winding, a cooling system etc. , and may be disposed in the stator or the rotor of the machine, or in both.
- Such a machine has its magnetic circuit designed with a threaded conductor, which is insulated with a solid insulation and in which earth has been incorporated.
- stator slots In order to be able to explain and describe the non-conventional machine, a brief description of a rotating electric machine will first be given, exemplified on the basis of a synchronous machine. The first part of the description substantially relates to the magnetic circuit of such a machine and how it is constructed according to classical technique. Since the magnetic circuit referred to in most cases is located in the stator, the magnetic circuit below will normally be described as a stator with a laminated sheet metal core, the winding of which will be referred to as a stator winding and slots arranged for the winding in the laminated core will be referred to as stator slots or simply slots.
- synchronous machines have a field winding in the rotor, where the main flux is generated by direct current, and an AC winding in the stator.
- the synchronous machines are normally of three-phase design and the invention mainly relates to such machines.
- the synchronous machines are designed with salient poles.
- cylin- drical rotors are used for two- or four-pole turbo generators and for double-fed machines. The latter have an AC winding in the rotor and this may be designed for the voltage levels of the power network.
- the stator body for large synchronous machines are often made of sheet steel with a welded construction.
- the laminated core is normally made from varnished 0.35 or 0.5 mm electric sheet.
- the laminated core is, at least for medium size and large machines divided into packages with radial or axial ventilation channels.
- the sheet is punched into segments, which are attached to the stator body by means of wedges/dovetails.
- the laminated core is retained by pressure fingers and pressure plates.
- the stator winding is located in slots in the laminated core and the slots have, as a rule, a cross section as a rectangle or as a trapetzoid.
- Polyphase AC windings are designed either as single layer or two-layer windings.
- single-layer wind- ings there is only one coil side per slot, and in the case of two-layer windings there are two coil sides per slot.
- coil side is meant one or more conductors brought together in height and/or width and provided with a common coil insulation, i.e. an insulation intended to withstand the rated voltage of the machine relative to earth.
- Two layer windings are usually designed as diamond windings, whereas the single-layer windings, which are relevant in this connection may be designed as diamond windings or as a flat winding.
- coil span is meant the distance in circular measure between two coil sides belonging to the same coil, either in relation to the relevant pole pitch or in the number of intermediate slot pitches.
- chording usually different variants of chording are used, for example fractional pitch, to give the winding the desired properties.
- the type of winding substantially describes how the coils in the slots, that is the coil sides, are connected together outside the stator, that is at the coil ends.
- a typical coil side is formed by so called Roebel bars, in which certain of the bars have been made hollow for a coolant.
- a Roebel bar comprises a plurality of rectangular, parallel connected copper conductors, which are transposed 360 degrees along the slot. Ringland bars with transpositions of 540 degrees and other transpositions also occur. The transposition is necessary to avoid circulating currents. Between each strand there is a thin insu- lation, e.g. epoxy/glass fibre.
- the main insulation between the slot and the conductors is made, e.g., of epoxy/glass fibre/mica and has externally a thin semiconducting earth potential layer used for equalizing the electrical field.
- a semiconducting earth potential layer used for equalizing the electrical field.
- an electric field control in the form of so called corona protection varnish intended to convert a radial field into an axial field, which means that the insulation on the coil ends occurs at a high potential relative to ground.
- the field control is a problem which sometimes gives rise to corona in the coil-end region, which may be destructive.
- the water- and oil-cooled synchronous machine described in J. Elektroteknika is intended for voltages up to 20 kV.
- the article describes a new insulation system consisting of oil/paper insulation, which makes it possible to emerse the stator completely in oil. The oil can then be used as a coolant while at the same time using it as insulation.
- a dielectric oil-separating ring is provided at the internal surface of the core.
- the stator winding is made from conductors with an oval hollow shape provided with oil and paper insulation. The coil sides with their insulation are secured in the slots made with rectangular cross section by means of wedges.
- coolant oil is used both in the hollow conductors and in holes in the stator walls.
- Such cooling systems entail a large number of connections of both oil and electricity at the coil-ends.
- the thick insulation also entails an increased radius of curvature of the conductors, which in turn results in an increased size of the winding overhang.
- stator part of a synchronous machine which comprises a magnetic core of laminated sheet with trapetsoidal slots for the stator winding.
- the slots are tapered since the need of insulation of the stator winding is smaller towards the interior of the rotor where that part of the winding which is located nearest the neutral point is located.
- stator part comprises a dielectric oil-separating cylinder nearest the inner surface of the core. This part may increase the magnetization requirement relative to a machine without this ring.
- the stator winding is made of oil-immersed cables with the same diameter for each coil layer. The layers are separated from each other by means of spacers in the slots and secured by wedges.
- the winding comprises two so called half-windings connected in series.
- One of the two half- windings is located, centered, inside an insulating sleeve.
- the conductors of the stator winding are cooled by surrounding oil.
- a disadvantage with such a large quantity of oil in the system is that the risk of leakage and the considerable amount of cleaning work which may result from a fault condition.
- Those parts of the insulating sleeve which are located outside the slots have a cylindrical part and a conical termination, the duty of which is to control the electric field strength in the region where the cable leaves the laminated core.
- the oil-cooled stator winding comprises a conventional high- voltage cable with the same dimension for all the layers.
- the cable is placed in stator slots formed as circular, radially located openings corresponding to the cross section area of the cable and the necessary space for fixing and for coolant.
- the different radially located layers of the winding are surrounded by and fixed in insulated tubes. Insulating spacers fix the tubes in the stator slot.
- an internal dielectric ring is also here needed for sealing the oil-coolant against the internal air gap.
- the structure shown does not have any reduction of the insulation or of the stator slots.
- the structure comprises a very thin radial waist between different stator slots, which means a large slot leakage flux which significantly influences the magnetization requirement of the machine.
- stator teeth should adjoin as closely to the casing of the coil sides as possible from a magnetical point of view. It is highly desirable to have a stator tooth having, at each radial level, a maximum width since the width of the tooth affects considerably the losses of the machine and, accordingly, the need for magnetization. This is particularly important for machines with higher voltage since the num- ber of conductors per slot becomes large therein.
- the primary object of the present invention is to devise ways to design the device and the method so as to achieve better protection for the object and, accordingly, a reduced load on the same, a fact which means that the object itself does not have to be designed to withstand a maximum of short-circuit currents/fault currents during relatively long time periods.
- a secondary object with the invention is to design the protection device and method such that an adequate protection is achieved for rotating electric machines, the design of which is based upon non-conventional design prin- ciples, which may mean that the design does not have the same resistance to fault-related over-currents, internal as well as external, as the conventional machines of today.
- the object indicated above is achieved in that the line between the object and the switching device is connected to an overcurrent reducing arrangement, which is actuatable for overcurrent reduction with assistance of an overcurrent conditions detecting arrangement within a time period substantially less than the break time of the switching device, and that between the connection of the overcurrent reducing arrangement to the line and the object, there is provided a current limiter.
- the invention is based upon the principle not to rely for breaking purposes only upon a switching device which finally establishes galvanic separation, but instead use a rapidly operating overcurrent reducing arrangement, which, without effecting any real breaking of the overcurrent, nevertheless reduces the same to such an extent that the object under protection will be sub- jected to substantially reduced strains and, accordingly, a smaller amount of damage.
- the reduced overcurrent/fault current means, accordingly, that when the switching device establishes galvanic separation, the total energy injection into the protected object will have been much smaller than in absence of the overcurrent reducing arrangement.
- the current limiter is of such a nature that it is rapidly operating for current reduction to such an extent that the strains imposed on the object will be dramatically reduced without the current limiter having to effect any total breaking of the overcurrent/fault current.
- the overcurrent reducing arrangement is designed as comprising an overcurrent diverter for diversion of over- currents to earth or otherwise another unit having a lower potential than the network/equipment.
- the current limiter according to the invention is suitably based on current limitation by means of a constant or variable inductance and/or resistance or other impedance.
- the invention is applicable on rotating electric machines having magnetic circuits designed by means of cable technology. These machines may under certain conditions become sensitive to electrical faults. Such a design may for instance be given a lower impedance than what is considered conventional today within the power field. This means a lower resistance against fault-related over-currents than that presented by conventional machines of today. If the machines, besides, have been designed from the start to operate with a higher electrical voltage than the conventional machines of today, the strain on the electrical insulation system of the machine, caused by the resulting higher electrical field, becomes, of course, greater.
- the machine may be more efficient, more economical, mechani- cally lighter, more reliable, less expensive to use and generally more economical than conventional machines, and the machine may manage without the usual connection to other electromagnetic machines, but such a machine places great demands on the electrical protection to eliminate, or at least reduce, the consequences of a breakdown in the machine in question.
- a combination of the protection device according to the invention and a rotating electric machine designed in this way means, accordingly, an optimization of the plant in its entirety.
- the electric machine primarily intended with the invention operates with such a high voltage that the ⁇ /Y-connected step-up transformer mentioned above may be omitted, i.e. machines with a considerably higher voltage than machines according to the state of the art is intended in order to be able to perform direct connection to power networks at all types of high voltage. This means considerably lower investment costs for systems with a rotating electric machine and the total efficiency of the system can be increased.
- a rotating electric machine according to the invention entails a considerably reduced thermal stress on the stator. Temporary overloads of the machine does become less critical and it will be possible to drive a machine at overload for a longer period of time without running the risk of damage arising. This means considerable advantages for owners of power generating plants, who are forced today, in case of operational disturbances, to rapidly switch to other equipment in order to ensure the delivery requirements laid down by law. With a rotating electric machine of such a design here contemplated, the maintenance costs can be significantly reduced because a transformer does not have to be included in the system for connecting the machine to the power network.
- the invention also includes a synchronous compensator directly connected to the power network.
- the insulation system about said at least one current-carrying conductor included in the winding in question comprises an electrically insulating layer of a solid insulating material, about which there is arranged an outer layer of a semiconducting material. An inner layer of semiconducting material is arranged inwardly of the insulating layer. Said at least one conductor is arranged inwardly of the inner layer.
- the inner and outer layers have substantially equal coefficients of thermal expansion as the insulating material.
- both layers and the insulating material have substantially equal thermal coefficients of expansion.
- the electrical load on the insulation increases as a consequence of the fact that the semiconducting layers about the insulating material will form equipotential surfaces meaning that the electrical field in the insulating material will be distributed evenly over the same.
- the outer semiconducting layer is suitably connected to earth potential or otherwise a low potential. This means that for such a cable the outer layer about the insulating material may be kept at earth potential for the whole length of the cable.
- the outer semiconducting layer may also be cut off at suitable locations along the length of the conductor and each cut-off partial length may be directly connected to earth potential.
- a further improvement of the invention is achieved by making the coils and the slots, in which the coils are placed, round instead of rectangular. By making the cross section of the coils round, these will be surrounded by a constant magnetic field without concentrations where magnetic sepa- ration may arise. Also the electric field in the coil will be distributed evenly over the cross section and local loads on the insulation are considerably reduced. In addition, it is easier to place circular coils in slots in such a way that the number of coil sides per coil group may increase and an increase of the voltage may take place without the current in the conductors having to be increased.
- strands may be insulated from each other and only a small number of strands may be left uninsulated and in contact with the inner semiconducting layer to ensure that this is at the same potential as the conductor.
- the outer semiconducting layer should present such electrical properties that a potential equalization along the conductor is ensured. However, the outer layer may not present such conduction properties that a current will be carried along the surface, which could give cause to losses, which in turn could cause undesired thermal load.
- the inner semiconducting layer must have a sufficient electrical conductivity to ensure potential equalization and, accordingly, equalization of the electric field outside the layer but this requires, on the other hand, that the resistivity may not be too small. It is preferred that the resistivity for the inner and outer layers is in the range 10 -6 ⁇ cm - 100 k ⁇ cm, suitably 10 -3 - 1000 ⁇ cm, preferably 1-500 ⁇ cm.
- the use of a cable of a flexible type for forming the winding means that the winding work may occur by means of a threading operation where the cable is threaded into the openings of the slots in the magnetic cores. Since the outer semiconducting layer is connected to earth potential or otherwise a relatively low potential, it will essentially operate for enclosing the electrical field inwardly of the layer.
- the use of an insulation system comprising a solid insulation surrounded by inner and outer semiconducting layers for enclosing the electrical field in the insulation means a substantial improvement compared with the prior art and eliminates entirely the need for resorting to liquid or gaseous insulation materials.
- a machine according to the invention has a number of features, which substantially distinguishes it from the prior art with respect to classical machine technology and the machine technology which has been published during the last years:
- the winding is made of a cable having one or more solidly insulated conductors with a conducting layer around the insulation.
- cables are preferably used with a circular cross sec- tion. However, in order to obtain a better packing density, cables with another cross section may be used
- the design of the slots is adapted to the cross section of the cable of the winding in such a way that the slots are formed as a number of axially and radially outwardly of each other extending cylindrical openings with an open waist running between the layers of the stator winding
- the design of the slots is adapted to the trapped insulation of the slots
- the development with respect to the strands means that the conductor of the winding consists of a number of layers combined with each other, i.e. not necessarily adequately transposed with respect to each other, of strands, including both uninsulated and insulated strands
- the development with respect to the outer casing means that the outer casing is cut off at suitable locations along the length of the conductor and each cut-off partial length is directly connected to earth potential
- the winding is preferably carried out as a multi-layer concentrical cable winding to decrease the number of coil- end crossings.
- the trapped insulation means that a nearly constant tooth width may be used independently of the radial propagation - the use of such a cable means that the outer semiconducting layer of the winding may be kept at earth potential along the whole length thereof
- an important advantage is that the electrical field is near zero in the coil-end region outside the outer semiconducting layer and that the electrical field does not have to be controlled when the layer is at earth poten- tial. This means that one cannot get any field concentrations, neither in the core, in coil-end regions nor in the transition therebetween
- a rotating electric machine means a considerable number of important advan- tages in relation to corresponding prior art machines.
- the machine can be connected directly to a power network at all types of high voltage.
- earth potential has been consistently conducted along the whole winding, which means that the coil-end region can be made compact and that support means in the coil-end region can be applied at practically earth potential.
- oil-based insulation and cooling systems disappear. This means that no sealing problems may arise and that the dielectric ring previously mentioned is not needed.
- One advantage is also that all forced cooling can be made at ground potential.
- Fig 1 is a purely diagrammatical view illustrating the basic aspects behind the solution according to the invention
- 2d are diagrams illustrating in a diagrammatical form and in a comparative way fault current developments and the energy development with and without the protection device according to the invention
- Fig 3 is a diagrammatical view illustrating a conceivable design of a device according to the invention.
- Figs 4-9 are views partly corresponding to Fig 3 of dif- ferent alternative embodiment of the invention with regard to the current limiter denoted 6;
- Fig 10 is a diagrammatical view illustrating a possible design of the overcurrent reducing arrangement
- ig 11 is a diagrammatical view illustrating the device according to the invention applied in connection with a power plant comprising a generator, a transformer and a power network coupled thereto;
- ig 12 illustrates parts contained in a cable intended to form the winding for a magnetic circuit of a rotating electric machine of a kind particularly well suited to be protected by the protection device according to the invention.
- ig 13 illustrates in an axial end view an embodiment of a sector/pole pitch of a magnetic circuit in a rotating electric machine, for which the protection device according to the invention is particularly well suited.
- FIG. 1 An electric power plant comprising a protected object 1 is shown in Fig 1.
- this object could for instance consist of a generator.
- This object is connected, via a line 2, to an external distribution net- work 3.
- the unit denoted 3 could be formed by some other equipment contained in the power plant.
- the power plant involved is conceived to be of such a nature that it is the object 1 itself which primarily is intended to be protected against fault cur- rents from the network/equipment 3 when there occurs a fault in the object 1 giving rise to a fault current from the network/equipment 3 towards the object 1 so that the fault current will flow through the object.
- Said fault may consist in a short-circuit having been formed in the ob- ject 1.
- a short-circuit is a conduction path, which is not intended, between two or more points.
- the short-circuit may for instance consist of an arc. This short-circuit and the resulting violent current flow may involve considerable damages and even a total break-down of the object 1.
- the designation 3 will, to simplify the description, always be mentioned as consisting of an external power network. However, it should be kept in mind that some other equipment may be involved instead of such a network, as long as said equipment causes violent current flows through the object 1 when there is a fault.
- a conventional circuit breaker 4 is arranged in the line 2 between the object 1 and the network 3.
- This circuit breaker comprises at least one own sensor for sensing circumstances indicative of the fact that there is an overcurrent flowing in the line 2. Such circumstances may be currents/voltages but also other indicating that a fault is at hand.
- the sensor may be an arc sensor or a sensor recording short circuit sound etc.
- the circuit breaker 4 is activated for breaking of the connection between the object 1 and the network 3.
- the circuit breaker 4 must, however, break the total short circuit current/fault current.
- the circuit breaker must be designed to fulfil highly placed requirements, which in practice means that it will operate relatively slowly.
- Fig 2a it is illustrated in a current/time-diagram that when a fault, for instance a short circuit in the object 1, occurs at the time f au ⁇ t, the fault current in the line denoted 2 in Fig 1 rapidly assumes the magnitude ⁇ .
- This fault current i ⁇ is broken by means of the circuit breaker 4 at t ] _, which is at least within 150 ms after tf au] _- [ -.
- Fig 2b illustrates the diagram i ⁇ -t and, accordingly, the energy developed in the protected object 1 as a consequence of the short circuit therein.
- the energy injection into the object occurring as a consequence of the short-circuit current is, accordingly, represented by the total area of the outer rectan- gle in Fig 2d.
- the circuit breaker 4 is of such a design that it establishes galvanic separation by separation of metallic contacts. Accordingly, the circuit breaker 4 comprises, as a rule, required auxiliary equipment for arc extinguishing.
- the line 2 between the object 1 and the switching device 4 is connected to an arrangement reducing overcurrents towards the apparatus 1 and generally denoted 5.
- the arrangement is actuatable for overcurrent reduction with the assistance of an overcurrent conditions detecting arrangement within a time period substantially less than the break time of the circuit breaker 4.
- This arrangement 5 is, accordingly, designed such that it does not have to establish any galvanic separation. Therefore, conditions are created to very rapidly establish a current reduction without having to accomplish any total elimination of the current flowing from the network 3 towards the protected object 1.
- Fig 2b illustrates in contrast to the case according to Fig 2a that the overcurrent reducing arrangement 5 according to the invention is activated upon occurrence of a short circuit current at the time tf au ⁇ -t- for overcurrent reduction to the level ⁇ 2 a the time t2.
- the time interval f au ⁇ -t-t2 represents, accordingly, the reaction time of the overcurrent reducing arrangement 5.
- the task of the arrangement 5 not to break but only reduce the fault current, the arrangement may be caused to react extremely rapidly, which will be discussed more closely hereunder.
- current reduction from the level i ⁇ to the level ⁇ 2 is intended to be accomplished within one or a few ms after unacceptable overcurrent conditions having been detected. It is then aimed at to accomplish the current reduction in a shorter time than 1 ms, and preferably more rapidly than 1 microsecond.
- the device comprises a current limiter generally denoted 6 and arranged in the line 2 between the connection of the arrangement 5 to the line 2 and the object 1.
- This current limiter is adapted to operate for current limitation primarily in a direction towards the object 1 but in certain fault cases also in a direction away from the object.
- the current limiter 6 may be arranged to be brought into operation for current limi- tation as rapidly as or even more rapidly than the overcurrent reducing arrangement 5.
- the current limiter could be designed to be activated for current limitation not until the over-current from the network 3 towards the object 1 has been reduced by means of the over-current reducing arrangement 5, but of course the current limiter 6 should be brought to activity for current limitation substantially more early than the time when the circuit breaker 4 breaks. From that stated it appears that it is suitable that the current limiter 6 is coupled to the line 2 in such a way that it is the current reduced by means of the over-current reducing arrangement which in an even more reduced extent will flow through the current limiter 6.
- Fig 2b illustrates the action of the current limiter 6.
- the current limiter 6 enters into operation for current limitation at the time t3, which in the example would mean that the duration of the current 2 reduced by means of the over-current reducing arrangement 5 has been substantially limited, namely to the time span ⁇ -t ⁇ -
- the representations in Fig 2 are to be considered as purely diagrammatical.
- the time 3, when the current limiter 6 is activated may be much earlier and even earlier than the time for activation of the overcurrent reducing arrangement 5 at the time t2- It appears from Fig 2b that the fault current after the time t3 is reduced to the level i3.
- the dimensioning of the arrangement 5 and the current limiter 6 is conceived to be carried out such that the arrangement 5 reduces the fault current and the voltage to be restricted by means of the current limiter 6 to substantially lower levels.
- a realistic activation time as far as the current limiter 6 is concerned is 1 ms, the dimensioning possibly being possible to carry out such that the current limiter 6 is caused to delimit the current not until after the arrangement 5 has reduced the current flowing through the limiter 6 to at least a substantial degree. As pointed out, this is not a requirement but the opposite case would also be possible.
- alternating current connections In a multi phase arrangement with alternating current, the line denoted 2 may be considered as forming one of the phases in a multi phase alternating current system.
- the device according to the invention may be realized so that either all phases are subjected to the protecting function according to the invention in case of a detected error, or that only that or those phases where a fault current is obtained is subjected to current limitation.
- the overcurrent reducing arrangement generally denoted 5 comprises an overcurrent diverter 7 for diverting overcurrents to earth 8 or otherwise another unit having a lower potential than the net- work 3.
- the overcurrent diverter may be considered as forming a current divider which rapidly establishes a short circuit to earth or otherwise a low potential 8 for the purpose of diverting at least a substantial part of the current flowing in the line 2 so that said current does not reach the object 1 to be protected.
- the overcurrent diverter 7 should be able to establish a short circuit having a better conductivity than the one corresponding to the short circuit fault in the object 1 to be protected so that accordingly a main part of the fault current is diverted to earth or otherwise a lower potential via the overcurrent diverter 7. It appears from this that, accordingly, in a normal fault case, the energy injection into the object 1 in case of a fault becomes substantially smaller than that which is indicated in Fig 2d as a consequence of lower current level i2 as well as shorter time span 2 ⁇ t3-
- the overcurrent diverter 7 comprises switch means coupled between earth 8 or said lower potential and the line 2 between the object 1 and the network 3.
- This switch means comprises a control member 9 and a switch member 10.
- This switch member may for instance be formed by at least one semiconductor component, for instance a thyristor, which is open in a normal state, i.e. isolating in relation to earth, but via the control member 9 may be brought into an active, conducting state in a very short time in order to establish current reduction by diversion to earth.
- an overcurrent conditions detecting arrangement may comprise at least one and preferably several sensors 11-13 suitable for detecting such overcurrent situations requiring activation of the protection function. As also appears from Fig 3, these sensors may include the sensor denoted 13 located in the object 1 or in its vicinity. Furthermore, the detector arrangement comprises a sensor 11 adapted to sense overcurrent conditions in the line 2 upstreams of the connection of the overcurrent reducing arrangement 5 and the line 2. As is also explained in the following, it is suitable that a further sensor 12 is provided to sense the current flowing in the line 2 towards the object 1 to be protected, i.e. the current which has been reduced by means of the overcurrent reducing arrangement 5.
- the senor 12 is capable of sensing the current flowing in the line 2 in a direction away from the object 1, for instance in cases where energy magnetically stored in the object 1 gives rise to a current directed away from the object 1.
- the sensors 11-13 do not necessarily have to be constituted by only current and/or voltage sensing sensors.
- the sensors may be of such nature that they generally speaking may sense any conditions indicative of the occurrence of a fault of the nature requiring initiation of a protection function.
- the device is designed such that the control unit 14 thereof will control the further breaker 6 to closing, in case it would have been open, and, in addition, the overcurrent reducing arrangement 5 is activated such that the short circuit current may be diverted by means of the same.
- the function on occurrence of a short circuit therein could be such that the short circuit first gives rise to a violent flow of current into the transfor- mator, which is detected and gives rise to activation of the arrangement 5 for the purpose of current diversion.
- the current limiter 6 is caused to reduce the current, but, controlled by means of the control unit 14, possibly not earlier than leaving time for the energy, in occurring cases, magnetically stored in the generator 1 to flow away from the generator 1 and be diverted via the arrangement 5.
- the device comprises a control unit generally denoted 14. This is connected to the sensors 11-13, to the overcurrent reducing arrangement 5 and to the current limiter 6. The operation is such that when the control unit 14 via one or more of the sensors 11-13 receives signals indicating occurrence of unacceptable fault currents towards the object 1, the overcurrent reducing ar- rangement 5 is immediately controlled to rapidly provide the required current reduction.
- the control unit 14 may be arranged such that when the sensor 12 has sensed that the current or voltage has been reduced to a sufficient degree, it controls the current limiter 6 to obtain opera- tion thereof for breaking when the overcurrent is below a predetermined level.
- the embodiment may alternatively also be such that the current limiter 6 is controlled to limit the current a certain predetermined time after the overcurrent reducing arrangement having been controlled to carry out current reduction.
- the circuit breaker 4 may comprise a detector arrangement of its own for detection of overcurrent situations or otherwise the circuit breaker may be controlled via the control unit 14 based upon information from the same sen- sors 11-13 also controlling the operation of the overcurrent reducing arrangement.
- the current limiter 6 is formed by an inductance 27 provided in the line 2.
- Such an inductance achieved by means of a coil has the result that at a certain increase of the current, a back electromotive force arises, which counteracts increase of current.
- An advantage with this embodiment is that it is extremely simple and furthermore, it gives rise to, when a fault occurs, a rapid limitation of the current flow towards the object 1 without need for active control.
- the switch means 10 of the overcurrent reducing arrangement 5 In absence of a fault, the circuit breaker is closed whereas the switch means 10 of the overcurrent reducing arrangement 5 is open, i.e. in a non- conductive state. In this situation the switch means 10 must, of course, have an adequate electrical strength so that it is not unintentionally brought into a conducting state. Over-voltage conditions appearing in the line 2 as a consequence of athmospheric (lightning) circumstances or coupling measures may, thus, not cause the voltage strength of the closing means 10 in its non-conducting state to be exceeded.
- it is suitable to couple at least one surge arrester 22 in parallel over the switch means 10. In the example, such surge arresters are illustrated on either side of the switch means 10. The surge arresters have, accordingly, the purpose to divert such over-voltages which otherwise could risk to cause inadvertent breakthrough in the switch means 10.
- the breaking function is initiated as far as the circuit breaker 4 is concerned.
- the control unit 14 controls the over-current reducing arrangement 5 to effect such reduction, and this more closely by causing the switch means 10 into an electrically conducting state via control member 9. As described before, this may occur very rapidly, i.e.
- the current limiter 6 may, as well, enter into a rapid function to limit the current flowing into the line 2 towards (or possibly from) the object 1.
- breaking is carried out as the last measure by means of the circuit breaker 4.
- the over-current reducing arrangement 5 as well as the current limiter 6 are designed to be able to function repeatedly.
- the switch means 10 is reset into a non-conducting state, and the current limiter 6 is ready, so that the next time the circuit breaker 4 closes, the protective device is in a completely operational state.
- the arrangement 5 may require exchange of one or more parts in order to operate again.
- Fig 4 illustrates an alternative embodiment of the current limiter 6a.
- This embodiment comprises an inductance 28 and a capacitor 29, which form, in unison, a resonance circuit, which at resonance gives a very high impedance.
- the inductance and the capacitor are coupled parallel to each other.
- a switch 30 and the capacitor 29 are coupled in parallel over the inductance 28 placed in the line 2. Accordingly, the switch 30 and the condensator 29 are coupled inparallel over the inductance 28 placed in the line 2. Accordingly, the switch 30 and the condensator 29 are placed in series with each other.
- the coupler 30 has one or more contacts, which by means of a suitable operat- ing member 31 may be controlled for closing or opening respectively via the control unit 14.
- the current limiter 6a illustrated in Fig 4 operates in the following way: during normal operational conditions, the switch 30 is open.
- the impedance of the current limiter 6a is given by the inductance and the resistance of the inductor.
- the control unit 14 will control the switch means 10 for closing for the purpose of overcurrent di- version and furthermore, the control unit 14 will control the switch 30 to closing such that the capacitor 29 is coupled in and a parallel resonance circuit, which should be adjusted to the power frequency, is formed.
- the impedance of the current limiter 6a will be very high at resonance. As is also apparent from a compara- tive study of Fig 2b, a considerable current reduction down to the drawn current level i 3 is obtained.
- Fig 5 an alternative embodiment of the current limiter 6b is shown, this embodiment being based upon a se- ries resonance circuit comprising an inductance 32 and a capacitor 33 in series with each other and a switch 34 coupled in parallel over the capacitor 33.
- An operating member 35 for operating the contact or contacts of the switch 34 is under control from the control unit 14.
- the switch 34 over the capacitor 33 is open.
- the coil 32 in series with the capacitor 33 in series resonance (at for example 50 Hz) has a very small impedance. Transient fault currents are blocked by the coil 32.
- the voltage over the capacitor as well as the inductance is increased.
- By closing the switch 34 over the capacitor the same is shortcircuited. This involves a drastic increase of the total impedance, for what reason the current is limited.
- the inductance 32 may be made variable, for instance by short-circuiting parts of the winding or a winding located on the same core. In this way it becomes possible to continuously adjust the current limiter 6b to minimize the voltage drop over the current limiter during normal load.
- Another modification not shown in Fig 5 is to use a self-triggered spark gap instead of the switch 34 over the capacitor 33. In this way, a self-triggered function is achieved, i.e. the embodiment becomes passive in the sense that no particular control from any control unit is required.
- the current limiter 6c comprises a switch 36 arranged in the line 2 and in parallel over this switch a capacitor 37 and a resistor 38, the capacitor and resistor being coupled in parallel relative to each other.
- the switch 36 has in reality the character of a vacuum circuit breaker provided with transversely directed coils 39 to increase the arc voltage and achieve current commutation into the limiting resistor 38.
- the control unit 14 is arranged to control the switch 36 via an operating member 40.
- Fig 7 illustrates a current limiter 6d formed by a mechanical switch 41 having a commutation element 42 consisting of a large number of series-connected arc cham- bers.
- the arc chambers are made of a resistive material.
- the switch 41 opens, the arc short-circuits the resistive arc chamber.
- the arc moves into the arc chamber, the arc is divided into many subarcs. In this way the arcs are increasing the length of the resistive path between the contacts and an increasing resistance is achieved.
- control unit 14 is arranged to control the operation of the switch 41 via an operating member 43.
- Fig 8 illustrates a further embodiment of a current limiter 6e.
- This limiter comprises, in the embodiment, a fast semiconductor switch 44 and a parallel current-lim- iting impedance 45 and a voltage-limiting element 46, for instance a varistor.
- the semiconductor switch 44 may be formed by means of gate turn-off thyristors (GTO thyristors ) .
- a resistor is used as a current limiting impedance.
- the varistor 46 limits the over-voltage when the current is restricted. Under normal load conditions, the current flows through the semiconductors 44.
- the semiconductor switch 44 is opened under control via the control unit 14, preferably via a suitable operating member 47, and the current is commu- tated to the resistor 45.
- a current limiter 6f is illustrated in Fig 9, this limiter comprising a coil 48 connected in the line 2.
- the coil 48 is included in a reactor having an iron core 49. Between the iron core 49 of the reactor and the coil 48 there is provided a superconducting tubular screen 50. Under normal operation, the superconducting screen 50 screens-off the iron core from the coil, the inductance thus being relatively low. When the current exceeds a certain level, the superconduction ceases and the induc- tance increases drastically. Thus, a strong current limitation is obtained.
- the screening of the iron core from the coil occurs due to the Meissner-effeet.
- An advantage with the embodiment according to Fig 9 is, as far as current limiter 6f is concerned, that a small inductance is at hand in normal operation.
- a disadvantage is that in order to achieve superconduction, cooling to very low temperatures, for instance by liquid nitrogen, is required.
- Fig 10 illustrates an alternative embodiment of the overcurrent reducing arrangement 5.
- the embodiment according to Fig 10 is intended to involve causing of a medium present in a gap 24 between electrodes 23 to assume electrical conductivity by means of a control member 9a.
- This control member is arranged to control the operation of members 25 for causing or at least initiating the me- dium or a part thereof in the gap 24 into a conducting state.
- Said member 25 is in the example arranged to cause the medium in the gap 24 to assume electrical conductivity by causing or at least assisting in causing the medium to ionization/plasma.
- the members 25 comprise at least one laser, which by energy supply to the medium in the gap 24 provides for the ionization.
- a mirror 26 may be used for necessary diverting of the laser beam bundle.
- the embodiment according to Fig 10 may be such that the means 25 do not alone give rise to ionization/plasma in the entire electrode gap.
- the intention may be that an electrical field imposed over the gap should contribute in ionization/plasma formation, only a part of the medium in the gap being ionized by means of the members 25 so that thereafter the electrical field in the gap gives rise to establishment of plasma in the entire gap.
- Fig 11 illustrates a conventional embodiment in the sense that a generator lb via a transformer la is coupled to a power network 3a.
- the objects to be protected are, accordingly, represented by the transformer la and the generator lb.
- the over-current reducing arrangement 5a and the current limiter 6g and the ordinary circuit breaker 4a are, as can be seen, arranged similar to what appears from Fig 1 for the case that the object 1 shown therein is conceived to form the object la according to Fig 11. Accordingly, reference is in this regard made to the descrip- tions delivered with respect to Fig 1. The same is due for the protection function of the over-current reducing arrangement 5c and the current limiter 6i with respect to the generator lb.
- the generator lb could, accordingly, be considered equivalent with the object 1 in Fig 1 whereas the transformer la could be considered equivalent to the equipment 3 in Fig 1.
- the overcurrent reducing arrangement 5c and the current limiter 6i will, in combination with the conventional circuit breaker 4b, be able to protect the generator lb against violent flow of current in a direction away from the transformer la.
- the additional overcurrent reducing arrangement 5b with associated current limiter 6h are present.
- the current limiters 6g and 6i respectively are arranged in the connections between said over-current reducing arrangements 5a and 5b and the transformer la.
- the further over-current reducing arrangement 5b is intended to protect the transformer la from current flows towards the transformer from the generator lb.
- the circuit breaker 4b will be able to break independently of in which direction between the objects la and lb a protection function is desired.
- the inner current-carrying conductor comprises a number of non-insulated strands. Around the strands there is a semiconducting inner casing. Around this semiconducting inner casing, there is an insulating layer of solid insulation.
- XLPE cross- linked polyethylene
- EP ethylene-propyl- ene
- This insulating layer is surrounded by an outer semiconducting layer which in turn is surrounded by a metal shield and a mantle
- a power cable Such a cable will be referred to hereunder as a power cable.
- the cable 51 is described in the figure as comprising a current-carrying conductor 52 which comprises transposed both non-insulated and insulated strands. Electromechanically transposed, solidly insulated strands are also possible.
- a current-carrying conductor 52 which comprises transposed both non-insulated and insulated strands. Electromechanically transposed, solidly insulated strands are also possible.
- the cable used as a winding in the preferred embodiment does not have metal shield and external sheath. To avoid induced currents and losses associated therewith in the outer semiconducting layer, this is cut off, preferably in the coil end, that is, in the transitions from the sheet stack to the end windings.
- Each cut-off part is then connected to ground, whereby the outer semiconducting layer 55 will be maintained at, or near, ground potential in the whole cable length.
- the design of the magnetic circuit as regards the slots and the teeth, respectively, is of decisive importance.
- the slots should connect as closely as possible to the casing of the coil sides. It is also desirable that the teeth at each radial level are as wide as possible. This is important to minimize the losses, the magnetization requirement, etc., of the machine.
- FIG. 13 shows an embodiment of an axial end view of a sector/pole pitch 56 of a machine according to the invention.
- the rotor with the rotor pole is designated 57
- the stator is composed of a laminated core of electric sheets successively composed of sector-shaped sheets. From a back portion 58 of the core, located at the radially outermost end, a number of teeth 59 extend radially inwards towards the rotor. Between the teeth there is a corresponding number of slots 60.
- the use of cables 51 according to the above among other things permits the depth of the slots for high-voltage machines to be made larger than what is possible according to the state of the art.
- the slots have a cross section which is reduced towards the rotor since the need of cable insulation becomes lower for each winding layer towards the rotor.
- the slot substantially consists of a circular cross section 62 around each layer of the winding with narrower waist portions 63 between the layers. With some justification, such a slot cross section may be referred to as a "cycle chain slot".
- the cable which is used as a winding may be a conventional power cable as the one described above.
- the grounding of the outer semiconducting shield then takes place by stripping the metal shield and the sheath of the cable at suitable locations.
- the scope of the invention accommodates a large number of alternative embodiments, depending on the available cable dimensions as far as insulation and the outer semiconductor layer etc. are concerned, of a so-called cycle chain slot.
- the magnetic circuit may be located in the stator and/or the rotor of the rotating electric machine.
- the design of the magnetic circuit will largely correspond to the above description independently of whether the magnetic circuit is located in the stator and/or the rotor.
- a winding is preferably used which may be described as a multilayer, concentric cable winding.
- Such a winding means that the number of crossings at the coil ends has been minimized by placing all the coils within the same group radially outside one another. This also permits a simpler method for the manufacture and the threading of the stator winding in the different slots.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP50096898A JP2001505758A (en) | 1996-12-17 | 1997-05-27 | Apparatus and method for protecting objects against overcurrent by overcurrent reduction and current limiting |
BR9714794-0A BR9714794A (en) | 1996-12-17 | 1997-05-27 | Device and method related to the protection of an object against excessive currents, including reduction of excessive current and current limitation |
CA002275638A CA2275638A1 (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation |
EP97924463A EP0950276A1 (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation |
AU29876/97A AU2987697A (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-curren ts comprising over-current reduction and current limitation |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9604630A SE515677C2 (en) | 1996-12-17 | 1996-12-17 | Overcurrent magnitude limiting device for high voltage rotating equipment e.g. generator, motor |
SE9604630-5 | 1996-12-17 | ||
SE9700335-4 | 1997-02-03 | ||
SE9700335A SE508556C2 (en) | 1997-02-03 | 1997-02-03 | Power transformer and reactor with windings with conductors |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998027635A1 true WO1998027635A1 (en) | 1998-06-25 |
Family
ID=26662820
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE1997/000881 WO1998027635A1 (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation |
PCT/SE1997/000883 WO1998029929A1 (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE1997/000883 WO1998029929A1 (en) | 1996-12-17 | 1997-05-27 | Device and method relating to protection of an object against over-currents comprising over-current reduction and current limitation |
Country Status (9)
Country | Link |
---|---|
EP (2) | EP1008220A1 (en) |
JP (2) | JP2001505758A (en) |
CN (2) | CN1246210A (en) |
AU (2) | AU730114B2 (en) |
BR (2) | BR9714794A (en) |
CA (2) | CA2275619A1 (en) |
PL (2) | PL334091A1 (en) |
TR (2) | TR199901969T2 (en) |
WO (2) | WO1998027635A1 (en) |
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WO2002015361A1 (en) * | 2000-08-17 | 2002-02-21 | Siemens Aktiengesellschaft | Instant tripping device for short circuits in electrical dc and ac networks of surface and underwater vessels, especially combat vessels, and offshore installations |
WO2011159893A1 (en) * | 2010-06-17 | 2011-12-22 | Varian Semiconductor Equipment Associates, Inc. | Technique for limiting transmission of fault current |
EP2495745A1 (en) * | 2011-03-04 | 2012-09-05 | ABB Technology AG | Current-rise limitation in high-voltage DC systems |
WO2013134392A1 (en) * | 2012-03-06 | 2013-09-12 | Ferrotec (Usa) Corporation | Electrical breakdown limiter for a high voltage power supply |
EP2790285A1 (en) * | 2013-04-12 | 2014-10-15 | Alstom Technology Ltd | Current limiter |
WO2015154796A1 (en) * | 2014-04-08 | 2015-10-15 | Siemens Aktiengesellschaft | Method for protecting an electrical modular unit from overcurrent damage |
WO2015092553A3 (en) * | 2013-12-18 | 2015-10-29 | Ingeteam Power Technology, S.A. | Variable impedance device for a wind turbine |
EP3035482A1 (en) * | 2014-12-17 | 2016-06-22 | General Electric Company | Systems and methods for implementing series compensators in static ups |
EP3747100B1 (en) * | 2018-01-30 | 2022-03-16 | Hitachi Energy Switzerland AG | Surge arrestor dimensioning in a dc power transmission system |
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US8228645B2 (en) * | 2009-03-03 | 2012-07-24 | General Electric Company | Systems and methods for protecting a series capacitor bank |
EP2264729A1 (en) | 2009-06-18 | 2010-12-22 | ABB Technology Ltd | Method and device for detecting failure of a vacuum interrupter of an on load tap changer |
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JP6083570B2 (en) * | 2013-10-04 | 2017-02-22 | 音羽電機工業株式会社 | SPD with separator |
CN104360116A (en) * | 2014-11-12 | 2015-02-18 | 上海理工大学 | Current limiter |
US9681568B1 (en) | 2015-12-02 | 2017-06-13 | Ge Energy Power Conversion Technology Ltd | Compact stacked power modules for minimizing commutating inductance and methods for making the same |
KR101995684B1 (en) * | 2016-09-30 | 2019-07-02 | 가부시키가이샤 알박 | Power supply |
JP6289794B1 (en) * | 2016-09-30 | 2018-03-07 | 株式会社アルバック | Power supply |
US10897130B2 (en) * | 2018-03-30 | 2021-01-19 | The Boeing Company | Micro plasma limiter for RF and microwave circuit protection |
CN109687418B (en) * | 2019-01-29 | 2020-09-01 | 湖南大学 | Short-circuit current drainage device and method and power system comprising fault drainage device |
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1997
- 1997-05-27 TR TR1999/01969T patent/TR199901969T2/en unknown
- 1997-05-27 WO PCT/SE1997/000881 patent/WO1998027635A1/en not_active Application Discontinuation
- 1997-05-27 JP JP50096898A patent/JP2001505758A/en active Pending
- 1997-05-27 EP EP97924465A patent/EP1008220A1/en not_active Withdrawn
- 1997-05-27 BR BR9714794-0A patent/BR9714794A/en not_active Application Discontinuation
- 1997-05-27 CA CA002275619A patent/CA2275619A1/en not_active Abandoned
- 1997-05-27 BR BR9714227-1A patent/BR9714227A/en unknown
- 1997-05-27 JP JP50097098A patent/JP2001509357A/en active Pending
- 1997-05-27 CN CN97181826A patent/CN1246210A/en active Pending
- 1997-05-27 CN CN97181829A patent/CN1246213A/en active Pending
- 1997-05-27 EP EP97924463A patent/EP0950276A1/en not_active Withdrawn
- 1997-05-27 AU AU29878/97A patent/AU730114B2/en not_active Ceased
- 1997-05-27 TR TR1999/02195T patent/TR199902195T2/en unknown
- 1997-05-27 AU AU29876/97A patent/AU2987697A/en not_active Abandoned
- 1997-05-27 PL PL97334091A patent/PL334091A1/en unknown
- 1997-05-27 CA CA002275638A patent/CA2275638A1/en not_active Abandoned
- 1997-05-27 PL PL97334127A patent/PL334127A1/en unknown
- 1997-05-27 WO PCT/SE1997/000883 patent/WO1998029929A1/en not_active Application Discontinuation
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Cited By (19)
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WO2002015361A1 (en) * | 2000-08-17 | 2002-02-21 | Siemens Aktiengesellschaft | Instant tripping device for short circuits in electrical dc and ac networks of surface and underwater vessels, especially combat vessels, and offshore installations |
KR100842950B1 (en) * | 2000-08-17 | 2008-07-01 | 지멘스 악티엔게젤샤프트 | Instant tripping device for short circuits in electrical dc and ac networks of surface and underwater vessels, especially combat vessels, and offshore installations |
WO2011159893A1 (en) * | 2010-06-17 | 2011-12-22 | Varian Semiconductor Equipment Associates, Inc. | Technique for limiting transmission of fault current |
US8739396B2 (en) | 2010-06-17 | 2014-06-03 | Varian Semiconductor Equipment Associates, Inc. | Technique for limiting transmission of fault current |
EP2495745A1 (en) * | 2011-03-04 | 2012-09-05 | ABB Technology AG | Current-rise limitation in high-voltage DC systems |
WO2012119919A1 (en) * | 2011-03-04 | 2012-09-13 | Abb Technology Ag | Current-rise limitation in high-voltage dc systems |
CN103403830A (en) * | 2011-03-04 | 2013-11-20 | Abb技术有限公司 | Current-rise limitation in high-voltage DC systems |
WO2013134392A1 (en) * | 2012-03-06 | 2013-09-12 | Ferrotec (Usa) Corporation | Electrical breakdown limiter for a high voltage power supply |
EP2790285A1 (en) * | 2013-04-12 | 2014-10-15 | Alstom Technology Ltd | Current limiter |
WO2014166660A1 (en) * | 2013-04-12 | 2014-10-16 | Alstom Technology Ltd | Current limiter |
US9791876B2 (en) | 2013-04-12 | 2017-10-17 | General Electric Technology Gmbh | Current limiter |
WO2015092553A3 (en) * | 2013-12-18 | 2015-10-29 | Ingeteam Power Technology, S.A. | Variable impedance device for a wind turbine |
US10352304B2 (en) | 2013-12-18 | 2019-07-16 | Ingeteam Power Technology, S.A. | Variable impedance device for a wind turbine |
WO2015154796A1 (en) * | 2014-04-08 | 2015-10-15 | Siemens Aktiengesellschaft | Method for protecting an electrical modular unit from overcurrent damage |
KR101897725B1 (en) | 2014-04-08 | 2018-09-12 | 지멘스 악티엔게젤샤프트 | Method for protecting an electrical modular unit from overcurrent damage |
US10530240B2 (en) | 2014-04-08 | 2020-01-07 | Siemens Aktiengesellschaft | Method for protecting an electrical modular unit from overcurrent damage |
EP3035482A1 (en) * | 2014-12-17 | 2016-06-22 | General Electric Company | Systems and methods for implementing series compensators in static ups |
US10148122B2 (en) | 2014-12-17 | 2018-12-04 | Abb Schweiz Ag | Systems and methods for implementing series compensators in static UPS |
EP3747100B1 (en) * | 2018-01-30 | 2022-03-16 | Hitachi Energy Switzerland AG | Surge arrestor dimensioning in a dc power transmission system |
Also Published As
Publication number | Publication date |
---|---|
TR199902195T2 (en) | 2000-01-21 |
CA2275619A1 (en) | 1998-07-09 |
JP2001505758A (en) | 2001-04-24 |
CN1246210A (en) | 2000-03-01 |
WO1998029929A1 (en) | 1998-07-09 |
AU2987897A (en) | 1998-07-31 |
PL334127A1 (en) | 2000-02-14 |
EP1008220A1 (en) | 2000-06-14 |
AU730114B2 (en) | 2001-02-22 |
CA2275638A1 (en) | 1998-06-25 |
PL334091A1 (en) | 2000-01-31 |
TR199901969T2 (en) | 1999-11-22 |
BR9714794A (en) | 2000-07-11 |
CN1246213A (en) | 2000-03-01 |
EP0950276A1 (en) | 1999-10-20 |
JP2001509357A (en) | 2001-07-10 |
AU2987697A (en) | 1998-07-15 |
BR9714227A (en) | 2000-04-18 |
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