Abstract: An electromagnetic device includes a plurality of coils formed by winding conductors. At least some of the conductors are constructed by stacking conductor constructional elements so that an eddy current generated by a leakage flux linked to the conductor is divided. An outer insulating member is disposed on an outer circumferential surface of the conductor stack for electrically insulating the conductor stack from another member. An inner insulating member whose thickness is smaller than a thickness of the outer insulating member is disposed between the conductor constructional elements adjoining to each other in the same conductor stack.

Abstract: A rotating asynchronous converter and a generator device having a first stator connected to a first AC network with a first frequency f1, and a second stator connected to a second AC network with a second frequency f2. The converter has a rotor which rotates in dependence of the first and second frequencies f1, f2. The stators each have at least one winding formed of at least one current-carrying conductor, and an insulation system, formed of semiconducting layers each forming an equipotential surface, and a solid insulation between the semiconducting layers.

Abstract: A wind-power unit has a wind turbine has an electric generator connected to the wind turbine. The stator of the generator has a winding formed of a high-voltage cable having a core of conducting material, a first layer of semiconducting material surrounding the core, an insulating layer of solid material surrounding the first layer, and a second layer of semiconducting material surrounding th solid insulation. The wind turbine has a plurality of turbine blades running vertically and being connected to a turbine shaft. The generator is arranged at the lower end of the turbine shaft. A wind-power plant; the use of a wind-power unit; and a method of generating electric power are described.

Abstract: The present invention relates to a rotating asynchronous converter and a generator device. The converter comprises a first stator connected to a first AC network with a first frequency f1, and a second stator connected to a second AC network with a second frequency f2. The converter also comprises a rotor means which rotates in dependence of the first and second frequencies f1, f2. The stators each comprises at least one winding, wherein each winding comprises at least one current-carrying conductor, and each winding comprises an insulation system, which comprises on the one hand at least two semiconducting layers, wherein each layer constitutes substantially an equipotential surface, and on the other hand between them is arranged a solid insulation.

Abstract: The magnetic circuit of a generator in a wind power plant is arranged to directly supply a high supply voltage of 2-50 kV, preferably higher than 10 kV. The generator is provided with solid insulation and its winding includes a cable (6) comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by at least one outer and one inner semiconducting layer (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The stator winding may be produced with full or fractional slot winding, the phases of the winding being Y-connected. The Y-point may be insulated and protected from over-voltage by means of surge arrestors, or else the Y-point may be earthed via a suppression filter. The invention also relates to a wind power plant, a generator included in the plant and a variable speed system for such a plant.

Abstract: A method for mounting a tube in a space having a shape corresponding to the shape of the tube. The tube is inserted into the space, pressurized with a hot pressure medium causing the tube to expand until the space is filled, then a cold pressure medium is substituted for the hot pressure medium while maintaining constant pressure causing the tube to solidify in its expanded shape. Also, a rotating electric machine having such a tube between windings of a high-voltage cable in a stator slot.

Abstract: A rotating electric machine (1) has a rotor, a stator (2), and stator windings (3, 4). The windings (3, 4) include high voltage cable drawn through slots (5, 6) in the stator (2). Support members (8) are arranged inside the slots (5, 6) along and in contact with the windings (3, 4), said support members (8) comprising a hose (8?) with a substantially triangular cross-section. A wire (9) is extending through and being attached to each support member (8). When mounting the support members (8) air inside a support member (8) is evacuated in order to shrink the support member (8). Then the wire (9) extending through the support member (8) is used to pull the evacuated support member (8) into a slot (5, 6), whereupon the evacuated support member (8) is expanded by releasing the vacuum inside in order to make it clamp a cable inside a slot (5, 6) of the stator (2).

Abstract: A rotating electrical machine and method for making the machine, where the machine includes a high-voltage stator winding and elongated support devices for supporting the winding. The machine and method employ an arrangement of cable that is made of inner conductive strands, covered with a first semiconducting layer, which is covered with an insulating layer, which is covered with a second semiconducting layer. The cable is wound in slots in the stator such that separate cable lead-throughs are positioned in specific arrangements with respect to each other and in slots of the stator. The arrangement of the cable in the stator protects the integrity of the respective components in the cable and particularly the second semiconducting layer.

Abstract: A Roebel bar (10) for an electrical machine comprises a plurality of essentially parallel, transposed conductor elements (11, 12, 13), which, lying over and/or next to one another, form a bar with an essentially rectangular cross section, which is surrounded on the outside by an insulation (19) and has between the insulation (19) and the conductor elements (11, 12, 13) means (14, 14?; 15, 15?; 17, 18) for forming an inner corona protection (ICP). In the case of such a Roebel bar, particularly effective inner corona protection is achieved by the fact that the means for inner corona protection comprise preformed, angled profiles (17, 18) of an electrically conducting material, which, running in the longitudinal direction of the Roebel bar (10), enclose the edges of the bar formed by the conductor elements (11, 12, 13), and to which the insulation (19) is applied.

Abstract: A corona suppression apparatus for a dynamoelectric machine having a stator coil (12) covered with a corona suppression covering (16), the apparatus including a member (10) conducting to ground (20) abutting a top layer (28) of the corona suppression covering proximate an overlap region (18) of the corona suppression covering. The member may be positioned in a gap (30) between the stator coil corona suppression covering and a stator core clamping finger (24) extending from the stator core proximate the stator coil. The member may also be configured to exert a compressive force on the overlap region by being compression biased between the corona suppression covering and the stator core clamping finger.

Abstract: In a plant containing a turbo-generator the magnetic circuit of the turbo-generator is included in an electric generator which directly supplies a high supply voltage of 20-800 kV, preferably higher than 36 kV. The insulation of the generator is built up of a cable (6) comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by outer and inner semiconducting layers (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The phases of the winding are Y-connected. The Y-point may be insulated and protected from over-voltage by means of surge arresters, or else the Y-point may be earthed via a suppression filter.

Abstract: In a plant comprising one or more electric machines constructed with insulated conductors and connected for heavy current via insulated conductors, the magnetic circuit in at least one of these electric machines is connected directly to a high supply voltage of 20-800 kV, preferably higher than 36 kV. The insulation of the electric machine is built up of a cable (6) placed in its winding and comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by outer and inner semiconducting layers (34, 32) and intermediate insulating layers (33). The conductors (31) may be group-wise connected in parallel and semiconducting layers are therefore not required around every conductor in the group.

Abstract: A rotating asynchronous converter for connection of AC network with equal or different frequencies employs a first stator connected to a first AC network with a first frequency and a second stator connected to a second AC network with a second frequency, and a rotor which rotates in response to the first and second frequencies. The converter has at least one winding formed of a cable, including a conductor and a magnetically permeable, electric field confining insulating covering surrounding the conductor.

Abstract: The magnetic circuit of a generator in a hydro-generator plant is arranged to directly supply a high supply voltage of 20-800 kV, preferably higher than 36 kV. The generator is provided with solid insulation and its winding includes a cable (6) comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by at least one outer and one inner semiconducting layer (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The stator winding may be produced with full or fractional slot winding, the phases of the winding being Y-connected. The Y-point may be insulated and protected from over-voltage by means of surge arresters, or else the Y-point may be earthed via a suppression filter. The invention also relates to a hydro-generator plant, a generator included in the plant and a procedure for building such a plant.

Abstract: An electric high voltage AC machine intended to be directly connected to a distribution or transmission network (16) comprises at least one winding. This winding comprises at least one current-carrying conductor, a first layer having semiconducting properties provided around said conductor, a solid insulating layer provided around said first layer, and a second layer having semiconducting properties provided around said insulating layer. In addition grounding means (18, 24, 26, 28) are provided to connect at least one point of said winding to ground.

Abstract: The magnetic circuit of a synchronous compensator plant is included in an electric machine which is directly connected to a high supply voltage of 20-800 kV, preferably higher than 36 kV. The electric machine is provided with solid insulation and its winding(s) is/are built up of a cable (6) intended for high voltage comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by at least one outer and one inner semiconducting layer (34, 32) and intermediate insulating layers (33). The plant is made as a mobile unit.

Abstract: A rotating electric machine having a magnetic circuit which in one of the parts of a rotor and a stator of the machine comprises an element (1) having a slot for a winding of layers (14, 16) of cables (9) extending substantially axially and arranged substantially radially outside each other, said cables comprising an inner conductor (10) comprising a plurality of strands (13) and an insulation (11) arranged outside thereof, has a larger share of strands of the cables closest to the other part of the rotor and the stator electrically insulated (15) with respect to each other than in the cables in the cable layer (16) most far away from said other part.

Abstract: The magnetic circuit of synchronous compensator plant is included in an electric machine which is directly connected to a high supply voltage of 20-800 kV, preferably higher than 36 kV. The electric machine is provided with solid insulation and its winding(s) is/are built up of a cable (6) intended for high voltage comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by at least one outer and one inner semiconducting layer (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The phases of the winding are Y-connected, and the Y-point may be insulated and protected from over-voltage by means of surge arresters, or else the Y-point is earthed via a suppression filter. A procedure is used in the manufacture of a synchronous compensator for such plant, in which the cable used is threaded into the openings in the core for the magnetic circuit of the synchronous compensator.

Abstract: An electromagnetic device comprises a magnetic field generating electrical circuit including a winding (1) having at least one electrical conductor (2). The winding comprises a solid insulation (4) surrounded by outer and inner layers (3, 5) serving for equalization of potential and having semiconducting properties. Said at least one electrical conductor (2) is arranged interiorly of the inner semiconducting layer (3). The invention also relates to methods for electric field control and production of a magnetic circuit as well as use of a cable for obtaining a winding.

Abstract: A rotating electric machine for direct connection to all types of high-voltage networks, in which the magnetic circuit adapted for high voltage comprises a rotor, stator and windings. The winding comprising a conductor surrounded by a solid insulation system. The invention also relates to a method for manufacturing the same.

Abstract: A magnet wire for an electrical equipment system includes a conductor, an insulation coating at least a portion of the conductor for insulating the conductor, and at least one of a varnish and an epoxy coating at least a portion of the insulation, wherein at least one of the varnish and the epoxy include a corona suppressing material.

Abstract: The invention relates to a rotor (1) for a turbogenerator having a field winding (4) which is formed from hollow conductors (3), having a damper bar (8), having insulation (9) arranged between the damper bar and the field winding, having a wedge (15) and having a gas outlet zone (5) which is located in the central rotor region. In order to reduce the distance between the field winding and the wedge, provision is made for the damper bar to be interrupted and to be replaced by an insulating piece (10) in the gas outlet zone (5), and for the damper bar parts (8) to be electrically conductively bridged by the wedge (15).

Abstract: A method for making a dynamoelectric machine conductor bar, compromises providing a plurality of bundled together spiraling strand conductors having surrounding insulation to define a substantially rectangular shape with the strand conductors and strand insulation defining an opposing conductor bar end portion having an electrically insulated gap between the strand insulation adjacent the bar end portion; and applying a filler material to fill the gap to electrically shield the conductor bar end portion and to a greater than 0.080 to about 1.5 inch continuous outer radius surface end portion.

Abstract: An inductive drive motor is shown wherein a magnetic rotor is positioned within an enclosed space defined by a housing surface. A stator is positioned around the surface in close contact therewith wherein the rotor is positioned substantially centrally thereof. The stator includes windings around the perimeter thereof wherein a phased flow of current therein provides for the creation of a magnetic field for rotatively driving the rotor. The rotor can be connected to various devices for mixing or scraping various liquid contents within the enclosed space. The stator windings are completely encapsulated in a corrosion resistant material, such as, a suitable plastic. Thus, the inductive drive motor has an extended life when used in corrosive environments.

Abstract: A high voltage stator bar 20 (FIG. 7) is used in a power generation system and includes a core section having a core 32 and stator coil 23, including at least one coil involute. A ground wall insulation layer 40 overlies and surrounds the stator coil. An inner grounding electrode 42 overlies and surrounds at least a portion of the ground wall insulation layer and includes the at least one coil involute. An insulator 46 overlies and surrounds the inner grounding electrode and leaves at least one exposed area 51 of the inner grounding electrode. An outer grounding electrode 52 overlies and surrounds the insulator and is electrically connected to the inner grounding electrode at the at least one exposed area of the inner grounding electrode for relieving a build-up of internal voltage, thereby preventing partial discharge.

Abstract: A polyphase electric generator (10) is disclosed having a fixed output voltage configurable to virtually any voltage level within a certain range of voltages. The armature winding (18) of the generator is arranged in a combined Delta and Wye topology (60, 66). Each phase winding (20, 54) in the armature is partitioned into first and second sections of the phase winding (56, 58). The first sections (56, 62, 64) of each of the phase windings are arranged together in a Delta topology (60). Each of the second sections of each phase winding is arranged in a Wye topology (66) with a pair of the first winding sections. Each of the second sections (58) are connected at one end to a node (68) of the Delta topology where two of the first winding sections are connected. The opposite ends (70) of the second sections of each phase winding are connected to output terminals (26) of the armature to provide a line-to-line voltage output.

Abstract: The present invention provides a high voltage generator stator coil for power generation systems for preventing partial discharge. The high voltage generator stator coil preferably includes a plurality of metal strands that form a high voltage conductor, conductive resin-rich filler material positioned to make electrical contact with the plurality of metal strands, a conductive inner corona protector positioned to electrically contact and overlie the conductive resin-rich filler material, groundwall insulation positioned to overlie and surround the conductive inner corona protector, and a conductive outer corona protector positioned to overlie and surround the groundwall insulation. The present invention also provides a method for forming a high voltage generator stator coil. The method preferably includes abuttingly contacting a plurality of metal strands in a stacked configuration to thereby form a high voltage conductor having at least a substantially straight portion.

Abstract: An insulating material (10) for an electrical generator rotor and method of forming the same. An insulating substrate (12) is formed from a single layer of woven glass fabric (16) having a necessary thickness and coated with a thermosetting resin (18). A first side of the substrate (12) is adhered to a first layer of copper winding material (20) of an electrical generator. A second side of the substrate (12) is covered with a layer of contacting material (14), such as plastic film, paper, treated felt or coated glass fabric, to cover the rough as-formed surface of the substrate (12) resulting from the coating of the necessarily thick layer of fabric (16). The contacting material (14) provides a desired coefficient of friction to form a slip surface permitting relative movement between the first layer of copper winding material (20) and a second layer of copper winding material (24) disposed over the insulating material (10).

Abstract: A polyphase electric generator (10) is disclosed having a fixed output voltage configurable to virtually any voltage level within a certain range of voltages. The armature winding (18) of the generator is arranged in a combined Delta and Wye topology (60, 66). Each phase winding (20, 54) in the armature is partitioned into first and second sections of the phase winding (56, 58). The first sections (56, 62, 64) of each of the phase windings are arranged together in a Delta topology (60). Each of the second sections of each phase winding is arranged in a Wye topology (66) with a pair of the first winding sections. Each of the second sections (58) are connected at one end to a node (68) of the Delta topology where two of the first winding sections are connected. The opposite ends (70) of the second sections of each phase winding are connected to output terminals (26) of the armature to provide a line-to-line voltage output.

Abstract: Resin-impregnated sheet materials, such as fabrics, films, paper and tapes, for forming electrical insulation that exhibits significantly improved voltage endurance performance. The present invention finds particular use as groundwall insulation for high voltage generator stator bars, in which the groundwall insulation is formed by mica tape filled with submicron particles of silicon dioxide, aluminum oxide, titanium dioxide and/or zirconium dioxide, in combination with an unfilled mica tape impregnated with the same or compatible resin binder. The filled tape is preferably in the form of a mica paper having at least one woven fabric on at least one of its surfaces, a resin binder permeating the mica paper and woven fabric so as to bond the woven fabric to the mica paper, and oxide particles dispersed in the woven fabric.

Abstract: A stator for a high voltage generator has cable windings that are radially inserted into the stator slots. The stator is assembled as the cable windings are laid into the stator slots. The stator slots are left wide open to allow the cable windings and separator bars to be inserted in the slot as the stator is assembled. The open slots have sidewalls that are defined by stator teeth, which extend radially out from a rotor jig in the stator. As each coil section is laid in a slot, a separator bar is inserted over the coil so that another coil section can be laid into the stator. The coils are stacked in a slot and sandwiched between separator bars also in the slot. The separator bar is keyed to the sidewalls of the teeth to provide structural support for the cable windings.

Abstract: An end winding (10) of a high voltage air-cooled ac generator or motor is made more resistant to surface deterioration by corona activity by using a paint whose binder contains at least 20% by weight silicone. An end winding, including its insulated conductors and separator and support structures, are coated with the paint whose composition includes a solvent or thinner, optional pigments, and the binder containing at least 20% by weight silicone. The balance (if any) of the binder can be, for example, an alkyd, acrylic, phenolic or epoxy resin.

Abstract: A conductor winding configuration for a large electrical machine has a supporting body and at least one winding element. The at least one winding element is inserted into an associated slot in the supporting body and has at least one electrical conductor. The at least one electrical conductor is sheathed by insulation which, for its part, is surrounded by a first protective layer. The first protective layer is in turn surrounded by a second protective layer. The protective layers rest against one another with surfaces that ensure free movement of the protective layers against one another.

Abstract: A stator coil for a rotating electrical machine having a ground wall insulation of a stator coil impregnated with a resin, maintaining a releasing characteristic between the ground wall insulation and a slot of a stator core, preventing surface corona and exhibiting excellent characteristics for a long time. The stator coil of the rotating electrical machine has a conductor covered with an insulating layer and a surface-corona preventive layer, the stator coil being accommodated in the slot of a stator core and, together with the stator core, impregnated with a thermosetting resin so that the stator coil is integrated with the stator core. The surface-corona preventive layer has a wound semiconductive tape and a composite tape including a fluorine-containing non-bonding material layer on a second semiconductive tape.

Abstract: A supporting element or core stack for an electric winding, in particular for a stator of a turbogenerator, includes a supporting surface to which an electric conductor can be attached. The supporting surface is provided with a coating for corona shielding. A turbogenerator has the supporting element. A method of producing a corona shield for an electric winding disposed on a supporting element, includes providing the supporting element with a coating for corona shielding.

Abstract: A technique for forming stator coils for an electric motor is disclosed. The technique includes forming D-shaped or generally trapezoidal coils having a closed loop defining a long side and a short side joined by end portions. The coils are installed in a stator core having a plurality of slots formed around its inner periphery. The long sides of the coils are disposed in a predetermined position within these slots, such as in a lower position, while the short sides are disposed in opposite positions, such as in upper positions. The long sides extend beyond the short sides at end regions of the stator core. The end portions of each coil wrap around the ends of the stator core and incline from the long side of the respective coil to the short side thereof. Crossing points are established between the long side of each coil and end portions of adjacent coils.

Abstract: In a high-voltage insulated stator winding having at least one stator winding bar (10) for an electrical machine, which stator winding bar (10) is surrounded by winding insulation (13) which comprises a plurality of insulating layers (22) arranged one above the other, in which case each insulating layer (22) is composed of an insulating material arranged on a base (16), in particular in the form of Mica paper (14), improved dielectric utilization (withstand voltage) and improved thermal utilization (heat dissipation) are achieved to an equivalent extent in that a heat-resistant plastic film is used as the base (16), which plastic film is modified by introducing a filler which can resist corona discharges.

Abstract: A high voltage generator armature bar (10) that exhibits improved performance by forming one or more of its conductive components from a conductive material that uses a tin oxide-based composition as a conductive filler. The armature bar (10) is of the type having one or more tiers of conductor strands (12), strand insulation (14), conductive internal grading (20), groundwall insulation (22), conductive slot armoring (24), and preferably a transposition filler (18). The conductive internal grading (20), the conductive slot armoring (24) and/or the transposition filler (18) contain a conductive filler of antimony-doped tin oxide that may constitute the entire conductive filler, or can be present as a shell on the filler particles.

Abstract: An electromechanical machine includes a stator fixed with respect to a housing structure and a rotor fixed with respect to a driven shaft. The stator includes a magnetically permeable core having a plurality of parallel winding slots containing conductive windings. Coilheads are located at opposite axial ends of the magnetically permeable core where the windings turn to extend down a parallel winding slot. The motor is equipped with electrostatic shield arrangements in the winding slots and coilheads to reduce capacitive coupling between the stator and rotor during operation.

Abstract: An electromagnetic equipment such as dynamoelectric machine includes an electromagnetic coil formed by winding an insulated wire. The insulated wire is made of a bare conductor having, on its surface, two layers of an insulating coating composed of a varnish and a low-resistance conductive coating composed of a heat resisting varnish containing a conductive oxide. A coil formed of the insulated wire is applied to the whole electromagnetic coil or a coil part near a power supply terminal.

Abstract: A winding element for an electrical machine, in particular a turbogenerator, includes an electrically conductive conductor configuration for carrying an electric current, an insulating layer surrounding the conductor configuration and a protective configuration surrounding the insulating layer. The protective configuration includes an isolating layer disposed like a helix, and an at least slightly electrically conductive contact layer likewise disposed like a helix and overlapping itself. The contact layer traverses or passes through the isolating layer from an inner side facing the insulating layer to an outer side facing away from the insulating layer. A winding assembly for an electrical machine includes an electrically conductive winding support and a winding element circumferentially surrounded and electrically contacted by the winding support.

Abstract: A tapered electrode with a rounded tab portion and a grading electrode is disclosed for minimizing the concentration of current flow to localized areas of the electrode. The tapered electrode comprises a base portion and a tab portion with a rounded end. The grading electrode comprises areas of varying width and relative resistance which operate to grade current flow away from the terminal portion of the tapered electrode tab.

Abstract: A rotor for an induction motor of the squirrel cage type wherein the rotor bars are exposed to a resilient anti-sparking compound in the rotor slots of the machine. The rotor bars are provided with a longitudinal slot to permit the insertion of the anti-sparking compound after assembly of the squirrel cage rotor. Alternatively, the laminations may be shaped to produce a longitudinal groove in the rotor bar slot to permit the insertion of the anti-sparking compound in the groove so produced. Of course, both the rotor bar and the rotor slot may both be provided with complimentary slots adjacent one another in which the anti-sparking compound may be injected.

Abstract: Damaging shaft voltages in an induction motor are prevented by an electrostatic shield between the stator winding structure and the rotor structure. The electrostatic shield is held at the same potential as the grounded motor frame. The shield includes an aluminum strip in each winding slot, with one strip in firm engagement with the stator core. The strips are flat strips and extend beyond both ends of the slot to the outer end turns of the stator winding. This places that one strip at the ground reference potential of the motor frame. All strips are connected to the one grounded strip by an end ring. All others are insulated from the core. The strips are connected at only one end to avoid a squirrel cage winding affect.

Abstract: Stator bars and stator coils (winding elements) for a large dynamoelectric machine which are to be permanently placed in the slots of the magnetic core of the machine are wrapped so as to be surrounded on three sides with an elongated sheet of an elastomeric substance. A stretching device is attached to the two overlapping edges of the elastomeric sheet in such a manner as to be able to stretch the sheet around the winding element and thus reduce the thickness of the elastomer. The winding element surrounded by the stretched layer of the elastomeric substance is placed in a selected stator slot and the stretching device is detached from the elastomeric material. The elastomeric material attempts to regain its former thickness but is confined to the remaining space between the winding element and the sides of the slot. The offal is trimmed from the elastomeric substance and the winding element remains lodged in the slot.

Abstract: The corona-shielding arrangement for the stator winding of an electric machine, comprising a semiconductive textile corona-shielding strip wound around the major insulation of slot portion and end yoke portion of each bar of the stator winding is constructed such that the slot portion (10) of the stator winding bar is wound around in at least one layer with a first semiconductive, volume-conducting coronashielding strip (24) having an approximately constant degree of overlap. The end yoke portion is wound around in at least one layer with a second semiconductive, volume-conducting corona-shielding strip (24), the degree of overlap from the exit of the bar from the stator body (14) to the bar end becoming continuously smaller. This corona-shielding arrangement is economic to produce; the voltage characteristic in the longitudinal direction of the bar is simple to optimize.

Abstract: Improved turbine generators including stator coil bracing and methods for bonding stator coils to diamond spacers to reduce the leakage of Corona suppressive compositions, such as CORONOX.RTM., are provided. The apparatus and methods include wrapping a portion of the stator coils coated with the Corona suppressive compositions with a reinforced layer which has been impregnated with a room-temperature polermerizing resin. The preferred constructions increase the bond strength between the coils and diamond spacers to provide a more homogeneous stator unit.

Abstract: Resinous compositions used as electric insulation have unique corona-resistance increased from 10- to 100-fold or more by the addition of organoaluminate, organosilicate or fine alumina or silica of critical particle size, and dynamoelectric machines and transformers incorporating coils made of wire strands coated with these novel compositions consequently have substantially increased service lives.

Abstract: An arrangement for and method of limiting the electrical stress in a region of high electric field strength associated with high voltage equipment, especially power cables, employs two overlapping layers of semiconductive material that have different a.c. electrical impedance characteristics to surround the region. The inner layer may be a heat-shrinkable tube having a linear characteristic, and the outer layer may have a non-linear characteristic and be provided as an internal coating on a further heat-shrinkable tube of insulating material. Such an arrangement provides good electrical protection in terms of both a.c. and impulse performance.

Abstract: Conductor bar for electric machines operating at high voltage, including at least two subconductor packets being disposed side by side and being formed of mutually insulated subconductors, the subconductors being intertwined in such a manner that each subconductor occupies each possible physical position in at least one location within the conductor bar, an insulating sleeve, a semiconductor layer applied to the insulating sleeve, a further semiconductor layer disposed between the subconductor packets and the insulating sleeve, the conductor bar having a straight portion and narrow sides having a given width, a narrow-side subconductor bar crossing from one subconductor packet to another, the narrow-side subconductor bar being disposed at a given height filling a portion of the given width of the narrow side leaving a remaining width, hardenable cement layers being disposed substantially at the given height flanking the narrow-side conductor bar in vicinity of the crossing and filling the remaining width.