System for insulating the stator of a rotary electric machine, and rotary electric machine

Abstract

The present invention relates to an insulating system for a rotary electric machine that comprises anti-corona protection comprising an OCP layer (8) applied on an intermediate region and on at least part of a projected region and an ECP layer (9) applied on the projected region, in order to form at least one overlap region (P) in which the OCP (8) and ECP (9) layers overlap, the ECP layer (9) being compressed on the OCP layer (8) in the overlap region (P), and at least one main spacer shim (11) configured to be arranged between two adjacent coils (5a, 5b), the main spacer shim (11) comprising a single solid piece having a thickness E corresponding to a minimum distance required between the two adjacent coils.

Description

"Insulation System for Stator of Rotating Electrical Machine and Rotating Electrical Machine" FIELD OF THE INVENTION

[0001] The present invention relates to the field of electrical machines and, in particular, to rotating electrical machines operating in explosive atmospheres. BACKGROUND OF THE INVENTION

[0001] Rotating electrical machines are equipment used to convert electrical energy into mechanical energy, in the case of motors, and vice versa, in the case of generators. They are generally made up of four basic structures: the rotor, which is the rotating component that is directly or indirectly energized; a static element called the stator, which is also energized and typically subject to higher electrical voltages than the rotor; bearings, responsible for joining the static and rotating parts; and finally, the casing, which acts as an enclosure and promotes integration with other auxiliary systems.

[0002] Those skilled in the art know that rotating electrical machines, especially those operating in high voltage ranges, particularly those above 6.6 kV, are subject to surface and corona discharges due to ionization of the medium as a result of the high electric field in specific regions of the winding, resulting in sparking. Corona and partial discharge (PD) are frequently confused. Corona refers to a specific type of discharge, which is the ionization of the gas surrounding a surface of high electrical potential. It is common to describe a corona discharge as a discharge that extinguishes in the air from a surface. PD is the dielectric breakdown of a gaseous medium, connecting one surface to another, typically involving at least one electrically insulating surface, which occurs when the electric field exceeds the dielectric strength of the gaseous medium.According to the definition given by the IEC (International Electrotechnical Commission) standard, PD is a form of electrical discharge that occurs in a part of an insulating system, without causing a complete rupture of the system. PD occurs in specific locations within the insulating material, such as in defects. or discontinuities, or superficially. Although PD does not cause immediate insulation failure, its continued occurrence can lead to material degradation.

[0003] Explosive atmospheres are those that contain, in addition to oxygen, a proportion of gas, vapor, dust, or fibers, in which a spark from an electrical circuit, or the heating of equipment, can be a source of ignition, causing an explosion. This type of atmosphere is found, for example, in industries in the petrochemical, food, pharmaceutical, paper, and textile sectors.

[0004] Due to the risk associated with operating electrical machines in explosive atmospheres, such machines typically undergo rigorous certification processes to ensure that their characteristics meet the technical requirements for safe operation. Among these characteristics, those related to the insulation system are particularly relevant.

[0005] Currently, such requirements and criteria are defined in international technical standards, such as the IEC 60079 series standards for explosive atmospheres and IEC 60034 for electric motors. Thus, for example, a machine that is suitable for operating in an explosive atmosphere, an area classified as Zone 2 (flammable vapors or gases), with Ex ec (increased safety) protection for gas group IIC (acetylene or hydrogen), must meet the requirements of the IEC 60079-7 standard.

[0006] Atmospheres containing hydrogen represent a particularly high risk for the operation of equipment subject to surface and corona discharges, since this type of atmosphere requires low energy to be activated when compared to traditional environments. Therefore, group IIC exhibits lower ignition energy when compared to groups IIB and HA.

[0007] The manufacture of engines for explosive atmospheres plays a crucial role in sustainability, especially in green hydrogen plants, where safety, health, and environmental (EHS) regulations are very strict. These engines are designed to operate safely in environments with flammable gases, such as hydrogen, minimizing the risk of serious accidents and environmental damage. In addition to ensuring safety, they contribute to energy efficiency by contributing to the clean energy cycle and reducing gas emissions, while also... Extended durability minimizes resource waste. These practices promote a sustainable industry of essential inputs for a low-carbon economy.

[0008] Solutions aimed at mitigating surface discharges and corona discharges are known in the state of the art, such as techniques for equalizing and / or grading the surface potential. In this sense, the use of insulation layers in the electrical conductors of electrical machines is known, including so-called external corona protection (OCP, "Outer Corona protection") and end-winding corona protection (ECP, "End-winding Corona protection").

[0009] Despite known solutions, the state of the art is constantly searching for solutions that allow compliance with the criteria and requirements for the operation of electrical machines in explosive atmospheres. OBJECTIVES OF THE INVENTION

[0010] One of the objectives of the invention is to provide a rotating electrical machine capable of operating in explosive atmospheres that provide a low ignition point.

[0011] Another objective of the invention is to provide a rotating electric machine capable of operating in explosive atmospheres containing gases of group IIC, such as hydrogen, in specified proportions.

[0012] Another objective of the invention is to provide an insulation system for a rotating electrical machine that enables the machine to meet the criteria and requirements of Ex ec IIC certification as set out in IEC 60079-7. BRIEF DESCRIPTION OF THE INVENTION

[0013] The present invention achieves the above objectives by means of an insulation system for a rotating electrical machine comprising a housing that contains an active core with a rotor and a stator, the stator comprising a plurality of conductive bars that form the stator coils, each of the conductive bars comprising an intermediate region configured to be housed in a lamination bundle (stator core) and a projecting region that projects axially outward from the core, the coils receiving a layer of insulation. principal, the insulation system comprising:

[0014] An anti-Corona protection comprising an OCP protection applied over the intermediate region and over at least part of the projected region and an ECP protection applied over the projected region such that at least one overlapping region is formed in which the OCP and ECP protections are superimposed, the ECP protection being compressed over the OCP protection in the overlapping region, and the anti-Corona protection further comprising at least one final insulating layer applied over the ECP protection; and

[0015] at least one main spacer shim configured to be disposed between two adjacent coils, the main spacer shim comprising a single solid piece whose thickness corresponds to the minimum required distance between the two adjacent coils.

[0016] In one embodiment of the invention, the ECP protection is provided in the form of a single ECP tape, and the final insulating layer is applied over the ECP protection in the form of a seamless tape.

[0017] Preferably, the minimum required distance between adjacent coils is 7 mm for voltages of 6.6 kV and above.

[0018] The isolation system of the present invention may further comprise at least one adjustment shim whose thickness is a fraction of the thickness of the main spacer shim.

[0019] In embodiments of the invention, the insulation system further comprises at least one spacer configured to separate connecting cables from the stator, wherein at least one spacer comprises two plates with recesses configured for receiving the cables, the two plates being connected by means of thickness adjustment.

[0020] The present invention also relates to a rotating electrical machine comprising the insulation system according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in more detail below, with reference to the accompanying drawings, in which:

[0022] Figure 1 - is a schematic illustration of a known anti-Corona protection device from the state of the art;

[0023] Figure 2 - is a schematic illustration of an anti-Corona protection of an insulation system according to an embodiment of the present invention;

[0024] Figure 3 - is a schematic illustration of additional components of the insulation system according to an embodiment of the present invention; and

[0025] Figure 4 - is a schematic illustration of a spacer component of the insulation system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described below based on an exemplary embodiment of the present invention shown in Figures 1 to 4.

[0027] Figure 1 shows a known state-of-the-art corona protection solution. In Figure 1, the electrical conductor is exemplarily illustrated in the form of stator bars 1 that form the stator windings or coils. As can be seen in this figure, the corona protection solution comprises an OCP protection 2 provided in an intermediate section of bar 1, especially in the section that is internal to the core slot 3 and extends to the region immediately outside the slot 3. An ECP protection 4 is provided in the region of bar 1 that projects axially outward from the core.

[0028] "Axially" is used in this description with reference to a direction parallel to the mechanical axis of the electrical machine.

[0029] As is well known to those skilled in the art, state-of-the-art stator bars may also comprise an inner main insulation layer which may be formed, for example, by resin-impregnated mica particles or by a mica tape.

[0030] Figure 2 shows a first aspect of the insulation system of the present invention. In this first aspect, the conductor 5, which may comprise a stator bar 5, comprises a main insulation layer 7, an OCP shield 8, which extends into an intermediate region of the conductor 5 and partially into a projecting region that projects axially outward from the stator core 6, and An ECP 9 protection is provided over the projected region and at least partially overlaps, with compression, the OCP 8 protection. Thus, in the solution of the present invention, there is double protection against Corona in at least one overlapping portion P of the projected region, the double protection being formed by the overlapping of the OCP 8 and ECP 9 protections in at least one region P.

[0031] In the embodiment of the invention shown in the figures, region P has a length between approximately 10 mm and approximately 30 mm.

[0032] The term "projected region" as used here defines a region that projects axially outward from core package 6.

[0033] In the solution of the present invention, the overlapping region P between the OCP 8 and ECP 9 guards is subjected to compression, so that the ECP guard... 9 is compressed onto the OCP 8 protection. Such compression may be carried out by any suitable compression means, for example, with a “C” type press clamp or any press clamp known in the state of the art.

[0034] In one embodiment of the present invention, the insulation system further comprises at least one final insulating layer 10 applied over the ECP protection 9, wherein such final insulating layer 10 is preferably a mica tape applied without seams. The term "without seams" as used herein defines a tape applied as a continuous spiral, without cuts or interruptions in the material, or with cuts and interruptions so insignificant that they guarantee continuous contact between the cut / interrupted parts.

[0035] Thus, in the present invention, at the ends of the final insulating layer 10. Regions R1 and R2 are formed where the final insulating layer exceeds the ECP 9 protection.

[0036] In the embodiment shown in the figures, region R1 has a length of about 5 mm to about 20 mm from one end of the ECP 9 protection. Region R2 precedes the ECP 9 protection, preferably starting before the curve of the bar, and has a length of about 5 mm to about 20 mm.

[0037] In the illustrated embodiment of the present invention, the ECP 9 protection is Provided in the form of a single, seamless ECP 9 tape, ensuring electrical continuity for protection.

[0038] In one embodiment of the invention, the OCP 8 protection consists of fabric or film-based tapes, which may comprise a plurality of materials, such as polyester, silicone, or glass, impregnated with materials such as carbon black or metal oxides. The ECP 9 protection consists of fabric or film-based tapes, which may comprise a plurality of polymers, such as polyester, silicone, or glass, impregnated with polymeric material (such as, among others, epoxy or polyester) containing materials such as carbides, oxides, and / or carbon black.

[0039] Figure 3 illustrates a second aspect of the insulation system of the present invention. As can be seen in this figure, the insulation system of the present invention comprises at least one main spacer shim 11, configured as a single solid piece whose thickness is dimensioned to ensure a minimum required distance between two laterally adjacent coils 5a and 5b of the stator.

[0040] This minimum required distance is a distance designed to maintain the electric field at levels that reduce the probability of ionization of the medium, preventing the generation of electrical discharges or reducing the energy of any discharges to levels below that necessary to ignite the explosive atmosphere. In a preferred embodiment, the minimum required distance is at least 7 mm, so that the single piece forming the main spacer wedge 11 has a minimum thickness E of 7 mm.

[0041] The formation of the spacer block 11 as a single piece allows for a lower propensity for discharges, which would occur in a block formed by a succession of thinner blocks.

[0042] In one embodiment of the present invention, at least one adjusting shim 11a is further provided, the thickness of which is necessarily a fraction of the thickness E of the main spacer shim 11. This at least one adjusting shim 11a has the function of filling a possible gap formed when the distance between coils in The region where the main wedge 11 is installed is larger than the thickness E of the main wedge 11.

[0043] In this sense, as an example, in a situation where the thickness E of the main spacer shim 11 is X mm and the thickness e of the adjustment shim 11a is 0.2X mm, for a region with a distance between laterally adjacent coils 5a and 5b of 1.4X mm, one spacer shim 11 and two adjustment shims 11a will be used.

[0044] In a preferred embodiment of the invention, the main spacer wedge 11 and at least one adjustment wedge 11a are manufactured from a material with relative permittivity similar to that of the main insulation and are formed without machined edges.

[0045] For example, spacer and adjustment shims could be made of polymeric material, such as epoxy, polyester, polypropylene, polyamide or polyurethane, filled with solid material comprising some of the following materials: glass, silica, alumina, carbonates, talc, mica, fibers, quartz powder, among others.

[0046] As shown in Figure 3, the solution of the present invention may further comprise fastenings 12, such fastenings being provided over the wedges 11.

[0047] In embodiments of the present invention, the ties 12 are made in the form of ribbons, shirts or felt of fibers, such as, for example, fiberglass or polyester. It should be understood, however, that such ties are optional and could be dispensed with in the case of, for example, the use of expandable wedges.

[0048] Figure 4 illustrates a further aspect of a preferred embodiment of the insulation system of the present invention comprising the provision of at least one spacer 13 for the stator connecting cables 14.

[0049] Just as with the main spacer 11 and adjustment 11a, the spacer 13 for connecting cables 14 provides a minimum distance between the connecting cables 14, important for reducing the electric field in the medium to levels that prevent ionization of the medium, avoiding the generation of electrical discharges or reducing The energy from any discharges would be lower than the level required to ignite the explosive atmosphere.

[0050] In the embodiment of the invention shown in Figure 4, the spacer 13 comprises two plates 13a and 13b with recesses 13c configured for receiving cables 14, the two plates 13a and 13b being connected by means of thickness adjustment 15. In the illustrated embodiment, the thickness adjustment means 15 are two screws with nuts disposed at the ends of plates 13a and 13b.

[0051] Additionally, the insulation system of the present invention may comprise loops (not shown) arranged on any of the static structures of the machine, such as, for example, along the casing. The loop is intended to secure the cable separator, so as to ensure spacing between the cables and the internal or external surfaces of the static elements, when the electrical design so requires.

[0052] The insulation system of the present invention allows for the achievement of an electrical machine that fully meets the criteria and requirements of Ex ec IIC certification, and the present invention is preferably intended for machines operating in voltage ranges above 6.6 kV, more preferably in voltage ranges from 10 kV to 15 kV.

[0053] The association between the overlapping of the OCP and ECP made with compression, the absence of splices in the ECP, and the protection of the ECP region are of paramount importance to obtain the appropriate discharge levels for this type of machine. These characteristics allow for attenuation of the local electric field, avoiding external discharges, constituting the ideal design, with the synergistic effect achieved by such an association being essential for reaching the necessary magnitude of effect.

[0054] Maintaining minimum distances between elements, using special shims, proper arrangement of tie-downs, as well as cable separators and spacers, makes it possible to guarantee low discharge values ​​that allow for the design of this type of machine, which, in isolation, would not have as good an effect as that achieved by the combination of these characteristics.

[0055] Having described examples of preferred embodiments of the present It should be understood that the scope of the present invention encompasses other possible variations of the inventive concept described, being limited only by the content of the appended claims, including possible equivalents.

Claims

CLAIMS 1. Insulation system for a rotating electrical machine comprising a housing that houses an active core with a rotor and a stator, the stator comprising a plurality of conductive bars (5) forming the stator coils, each of the conductive bars (5) comprising an intermediate region configured to be housed in a stator core bundle (6) and a projecting region that projects axially outward from the core, the coils receiving a main insulation layer (7), the insulation system being characterized in that it comprises: an anti-Corona protection comprising an OCP protection (8) applied over the intermediate region and over at least part of the projecting region and an ECP protection (9) applied over the projecting region such that it is formed by at least one overlapping region (P) in which the OCP protections (8) and ECP protections (9) are overlapped, the ECP protection (9) being compressed over the OCP protection (8) in the overlapping region (P),and the anti-Corona protection further comprising at least one final insulating layer (10) applied over the ECP protection (9); and at least one main spacer wedge (11) configured to be disposed between two adjacent coils (5a, 5b), the main spacer wedge (11) comprising a single solid piece whose thickness E corresponds to a minimum required distance between the two adjacent coils (5a, 5b).

2. Insulation system according to claim 1, characterized in that: the ECP protection (9) is provided in the form of a single ECP tape (9); and at least one final insulating layer (10) is applied over the ECP protection (9) in the form of a seamless tape.

3. Insulation system, according to claim 1 or 2, characterized in that the minimum required distance is 7 mm for voltages of 6.6 kV and above.

4. Insulation system, according to any one of claims 1 to 3, characterized in that it further comprises at least one adjustment wedge. (11a) whose thickness e is a fraction of the thickness E of the main spacer wedge (11).

5. Insulation system, according to any one of claims 1 to 4, characterized in that it further comprises at least one spacer (13) configured to separate connecting cables (14) from the stator, or at least one spacer (13) comprising two plates (13a, 13b) with recesses (13c) configured for receiving the cables, the two plates (13a, 13b) being connected by means of thickness adjustment (15).

6. Rotating electrical machine comprising a housing that contains an active core with a rotor and a stator, the machine being characterized in that it comprises an insulation system as defined in any one of claims 1 to 5.

Images