EP2807657A1

EP2807657A1 - Material for insulation system, insulation system, external corona shield and an electric machine

Info

Publication number: EP2807657A1
Application number: EP13707309.4A
Authority: EP
Inventors: Mario Brockschmidt; Peter GRÖPPEL; Friedhelm Pohlmann; Claus Rohr; Roland Röding
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2012-03-26
Filing date: 2013-02-20
Publication date: 2014-12-03
Also published as: US20180068757A1; US20150041178A1; EP3905279A1; EP2645373A1; WO2013143787A1; US10902972B2; CN104303239B; CN104303239A; IN2014DN07431A

Abstract

High-voltage insulation systems are simplified and can have a thinner design by the use of an electrically conductive PTFE fabric, wherein the thermal conductivity is also improved.

Description

Material for insulation system, insulation system,

External corona protection and an electric machine

The invention relates to a material for insulation system, an insulation system, a Außenglimmschutz and an electric machine.

Potential control allows in rotating machines, such as e.g. Generators or high-voltage motors, the

Minimization of electrical voltages (potential differences) whereby the occurrence of partial and / or glow discharges can be reduced or completely avoided. In rotating electrical machines, the reliability of the insulation system is largely responsible for their operational safety. The insulation system has the task

electrical conductors (wires, coils, rods) permanently

against each other and against the stator core or the

Isolate environment. The external potential control has the task to establish an electrical contact between the

Earth potential lying stator core and the outside of the main insulation to realize. This will

ensured that no partial discharges occur in cavities in the area of the boundary layer of insulation and laminated core.

Here is to distinguish

External corona shielding (AGS) for generator winding bars produced in accordance with single rod production (AGS)

e)

• External corona shielding (AGS) for generator winding bars produced by GVPI process (AGS-G). For fully saturated stator windings (Global Vacuum Pressure Impregnation GVPI), the entire laminated core is impregnated and cured together with a fully installed winding. This is the bonding of the winding in the Grooves of the laminated core so tight that it through the

different coefficients of expansion of copper, iron and insulation to high thermomechanical stresses

between copper, insulation and iron comes after a certain number of heat plays (starts and stops of the

Generators) can lead to rupture of the interfaces. To prevent the column of an electrical

Potential difference are below and igniting there

Partial discharges destroying the insulation becomes one

External potential control (outer corona protection, OCP) used in Figure 1 as a double-layered

External corona protection, as used for potential control by means of G-VPI processed machines, is shown. About the current-Roebelstab from Kupparterteilleitern 40, an insulating base winding 70 is applied from fine mica tape, which smooths the edge radii of the thin copper section conductor 40 and increases.

A first graphite-containing Leitvliesband 100 is wound over this, which is connected via a contact strip 130 at only one point with the high voltage potential of the copper part conductor 40.

Only then is the main insulation 160 wound from fine luster glass. Instead of the copper subconductor now forms the first Leitvliesband 100, the high voltage electrode. It is

permanently bonded to the main insulation.

On the main insulation 160 follows the inner

An outer corona shield 110 made from a prior art material (conductive, flexible tape, especially from Krempel), an outermost divider 190 ', and an outer corona shield 200. An outer corona shield 140 interwoven in the outermost divider 190' connects inner 110 and outer 200 outer corona shields. The resulting when starting and stopping the generator

thermomechanical stresses between the

Copper conductor bond and the insulation can after some operating time to local detachment of the insulating sleeve of Conduct ladder without igniting the dreaded partial discharges in the resulting columns. The area of

Delamination is potential free because of that

High voltage potential has been transferred to the main backing firmly baking Leitvlies. This IPS design on the highly stressed inner interface between conductor and insulation allows for decades of peak load operation of turbo generators without a noticeable

Partial discharge aging

It is therefore an object of the invention, o.g. To solve problems.

The object is achieved by an insulation material according to claim 1, insulation system according to claim 17, a

Außenglimmschutz according to claim 20 and an electrical

Machine according to claim 21.

In the dependent claims further advantageous measures are listed, which can be combined with each other in order to achieve further advantages.

Show it:

FIG. 1 shows an external potential control of a

Generator winding rod according to the prior art, Figure 2 shows an inventive external potential control and Figure 3 shows a generator.

The figures and the description only represent

Embodiments of the invention.

The invention consists in using hydrophobic material, in particular PTFE (Teflon) as insulation, in particular for such a high-voltage insulation system, wherein the insulation system is electrically conductive in layers

is designed. The high voltage isolation system may be a simple system or a more complex system as in FIG. The invention will be explained only with reference to PTFE as an example of a hydrophobic material.

Preferably, even the hydrophobic material or PTFE is designed to be electrically conductive. The PTFE is then a composite material.

This is preferably carried out in the production of the material, in particular by means of mixing in of electrically conductive material, of graphite, for example. by extrusion at the

Production, in which case preferably fibers are produced.

But it is also a subsequently electrically conductive coating of a fabric, a fiber, a Geleges, a membrane or a film possible.

The fabric is preferably formed from fibers which comprise the electrically conductive insulation material, in particular PTFE. This fabric is preferably in tape form and is wound onto the surface to be insulated for application (see Figure 2).

Likewise, a perforated band (in tissue form or the like), a perforated membrane or a perforated scrim (scrim as known from textile technology) can be used, ie it can be inserted into the band, into the tissue, into the membrane (which is already porous) or in the clutch introduced through holes. Preferably, therefore, the high-voltage insulation system in the outer corona protection fibers or a fabric of PTFE, wherein to achieve the electrical conductivity and between the fabric-forming structures preferably a electrically conductive material, preferably graphite

is available.

The AGS in the high-voltage insulation system in Figure 2 preferably comprises a fabric of PTFE, this being so

is designed so that the tissue has pores that can be infiltrated as described above by the described method.

The basic structure and mode of operation of the current AGS system according to FIG. 1 should remain unchanged

remain with the exception of the omission of the outer corona strip 140 and replacement of the crevice mica by the

PTFE-containing material according to the invention. It is also preferable to dispense with the outer corona shield 200 in FIG.

This gives the following advantages:

· Good impregnability, since it is a porous

Tissue acts and thus can be applied before curing.

• Unchanged resistance before and after impregnation, as the conductivity is due to fibers rather than particles like the AGS tape. (These have due to the enveloping the particles after impregnation

Plastic matrix has a different resistance value

Compared to the initial value).

The objectives for the AGS-G according to the invention are:

• simplified application / cost reduction

Reduced layer thickness of the double AGS by thinner ones

alternative

The approach for the AGS-G according to the invention is:

• Reduction of the layer thickness by using a

Separating layer, which has a defined mechanical Decoupling realized without that it comes to changing the electrical resistance. This is to be realized by replacing the double layer gap mica by hydrophobic tissue types. This may be in particular a Teflon tissue. The structure is done in the following way:

An improvement results according to the invention by the

Use of electrically conductive fabric 190 of PTFE, as this eliminates the "braiding" of the outer corona shielding tape 140 (Figure 1). This would allow a reduction of the layer thickness and the production costs (FIG. 2).

The inventive structure of an innovative

External potential control for use in the GVPI process allows for an insulation system that has state-of-the-art features, but has the benefits of:

• Determination of TE freedom after curing

· Comparable loss factors after execution of

Temperature cycle tests for accelerated

thermomechanical load

• comparable electrical durability under

Operating voltage load and at elevated

voltage stress

• comparable electrical durability under

Operating voltage load and at elevated

Stress load after removal at

different temperature cycles.

These investigations were carried out on generator winding bars with the following design:

• Aluminum profiles with a length of approx. 1.5 m and

Dimensions of learning x 5cm

• Number of layers of mica 8 + 1 layer IPS for one

Nominal voltage of 13,8kV

• Number of generator winding bars per collective: 6. A reduction of the layer thickness of the current AGS from about 450 μm to a value of about 100 μm was made possible.

FIG. 3 shows by way of example a generator as

electric machine.

According to Figure 3 extends a

Rotary machine arrangement, in particular a

Generator assembly 2 along a longitudinal axis 3 from a turbine-side end portion 6 to a pathogen side

End region 8. The generator arrangement 2 has a housing 10. In the turbine-side end portion 6 is a

Cooling device 12 is arranged. And that is in one

Cooler head 14, which is a part of the housing 11, two coolers 16 and a compressor in the form of a blower 18 with a fan hub 20 arranged. The fan hub 20 is seated on a rotor 22 which extends along the longitudinal axis 3 through the

Generator assembly 2 extends. Following the

Cooling device 12 in the direction of the longitudinal axis 3, the actual generator region 23 is arranged. In this area, the rotor 22 is surrounded by a stand 24 to form an air gap 26. The stand 24 has a

Stator winding with a turbine-side stator winding head 28A and with a pathogen-side stator winding head 28B on. Between the two stator winding heads 28A, 28B, a so-called laminated core 30 is arranged. Analogous to the stator 24, the rotor 22 has a turbine-side rotor winding head 32A and an exciter-side rotor winding head 32B.

Due to the usual in turbo generators high

Power density is a cooling of the generator assembly 2 in the generator region 23 is necessary. A particularly high

Cooling requirements here have the Ständerwickelköpfe 28A, 28B, and the Läuferwickelköpfe 32A, 32B. For cooling the

Generator region 23 has this a cooling system 34 which is supplied by the cooling device 12 with cooling gas. The cooling system 34 has a number of cooling gas channels 36A, D, 48, via which the cooling gas is circulated. A first cooling gas channel 36A extends in the axial direction and is arranged between the stator 24 and the housing 10. A second cooling gas channel 36 B is formed by the air gap 26. Further extending in the axial direction

Coolant gas channels 36C lead through the laminated core 30. To cool the rotor 22, a cooling gas channel 36D leads through it. The cooling gas flow in the generator region 23 and in the

Cooling device 12 is indicated in each case by arrows, wherein the dashed arrows indicate the flow path of the cold

Cooling gas and the solid arrows indicate the flow path of the heated cooling gas (hot gas).

To cool the Ständerwickelköpfe 28 A, 28 B divides the coming of the coolers 16 cooling gas flow in

turbine end 6 on. One partial flow serves for cooling the turbine-side stator winding head 28A and the other partial flow is forwarded via the cooling gas channel 36A to the exciter-side stator winding head 28B and split again. The one part is used to cool the

Ständerwickelkopfs 28B and flows from there as hot gas on the air gap 26 back again. The other part is passed through the cooling gas channels 36 C of the laminated core 30 and exits in the turbine-side end portion 6 as hot gas and is the coolers 16, respectively. For cooling the rotor winding heads 32A, 32B, cooling gas is introduced into the cooling gas passage 36D of the rotor 22 from both the turbine-side end portion 6 and from the turbine-side end portion 6

exciter-side end 8 initiated. A partial flow of the cooling gas flows through the respective rotor winding heads 32A, 32B and is then passed into the air gap 26 as hot gas and fed to the coolers 16. The remaining one

Partial flow is further passed through the rotor 22 in the cooling gas channel 36D, in such a way that the cooling gas from the two Läuferwickelköpfen 32A, 32B flows towards each other and is passed approximately in the central region 38 of the generator portion 23 in the air gap 26.

Claims

claims

1. Electrically conductive insulation material,

the hydrophobic material,

especially PTFE,

having,

in particular.

2. Insulation material according to claim 1,

the electrically conductive, hydrophobic material,

in particular has electrically conductive PTFE.

3. insulating material according to one or both of claims 1 or 2,

having fibers.

4. insulation material according to claim 3,

in which the fibers are hydrophobic, electrically conductive material,

in particular electrically conductive PTFE fibers

exhibit,

in particular, consist of it.

5. insulation material according to one or more of

Claims 1 to 4,

that a tissue,

in particular of fibers,

having,

that at least partially,

in particular completely comprises fibers according to claim 4. Insulating material according to one or more of

Claims 1, 2, 3, 4 or 5,

a tissue (5) of hydrophobic, electrically conductive material,

in particular of electrically conductive PTFE

having .

7. insulation material according to one or more of

Claims 1 to 5,

which represents a membrane.

8. insulation material according to one or more of

Claims 1, 2 or 3,

that represents a clutch.

9. insulation material according to one or more of

previous claims,

that makes a band.

10. insulation material according to one or more of

previous claims,

that is perforated.

11. insulation material according to one or more of

previous claims,

a perforated band of electrically conductive, hydrophobic material,

in particular of electrically conductive PTFE,

having .

12. Insulation material according to one or more of the preceding claims,

in the electrically conductive material in the hydrophobic material,

especially in PTFE,

is mixed.

13. insulation material according to one or more of

Claims 3 to 12,

in which electrically conductive material is distributed between the fibers, the scrim, the membrane or the fabric structure.

14. insulation material according to one or more of

previous claims,

in which the hydrophobic material, the PFTE, the fiber, the tissue, the membrane, the scrim or the band are coated with an electrically conductive layer.

15. insulation material according to one or more of

Claims 12, 13 or 14,

wherein the electrically conductive material is graphite.

16. insulation system according to claim 17,

having pores,

which are in particular infiltratable.

17. Layer-wise electrically conductive insulation system, in particular high-voltage system,

the hydrophobic material,

especially PTFE,

having .

18. Insulation system according to claim 17,

wrapped in ribbon.

19. insulation system according to one or both of claims 17 or 18,

in which the PTFE-containing material between inner

External corona shield (110) and outer

Outside corona protection material (200) is arranged.

20. external corona protection,

having an insulating material or a

Isolation system according to one or more of the preceding claims,

in particular consisting thereof.

21. Electrical machine with an insulating material or an insulation system according to one or more of the preceding claims 1 to 20,

in particular a generator.