CS253914B1 - Layered insulator of thermal class F to H - Google Patents

Abstract

The layered insulator is intended for slot insulation of rotating electrical machines of small and medium power, higher thermal classes. The layered slot insulation consists of a thin layer of heat-resistant aramid cardboard, covered on one or both sides with a protective layer of natural or synthetic fabrics, or mats using a highly heat-resistant organic binder. The solution will also be used as insulation of winding ends, positional and interphase insulation and surface insulation in transformers.

Description

The invention relates to a laminated insulator of thermal class F and H, intended mainly as groove insulation for rotating electrical machines of small to medium power, at low voltage.

To isolate magnetic circuits from windings in rotating electrical machines operating at higher temperatures, special single-layer or more frequent combinations of either bonded or loosely layered insulators are used. These are primarily materials based on stud, glass fabric, asbestos, or heat-resistant synthetic material.

The disadvantage of the types of groove insulation used so far is that they satisfy only one or only some of the electrical, assembly, operational or economic requirements at the same time. For example, the polyamide cardboard itself is thick, difficult to process and poorly impregnated. The use of glass fabric for layered insulation results in a deterioration of the bending properties and increased flight of fine glass fibers from the fabric or, in the case of using varnished glass fabric, the glass fabric fibrils are sprayed into the groove together with the varnish used.

The disadvantages of the prior art are eliminated by the solution according to the invention, where the insulator consists of synthetic cardboard made of heat-resistant aromatic polyamide with a density of 780 to 1100 kg/m ³ , a thickness of 0.05 to 0.25 mm, laminated on one or both sides with a protective material using a heat-resistant binder. As a protective material, glass fabric lubricated with polyurethane varnish, mica or glass paper for thermal class H and synthetic fiber mats, e.g. polyester mat for class F, are used. As a heat-resistant binder, a polyurethane, alkylepoxide or silicone binder is used.

The layered insulators according to the invention have an increased impregnator content by 10 to 15% as a result of the perfect supersaturation of the entire material with the binder, which results in an increase in heat transfer from the winding to the magnetic circuit by 10 to 20% and thus improves the short-term current and power loadability of the machine. While maintaining the essential electrical insulation and mechanical properties (Table 1), these insulators according to the invention have a reduced stiffness in the longitudinal direction (p) by 20 to 25%, in the transverse direction (n) by 15 to 22%, which is reflected in a simple method of shaping and low laboriousness during winding. As a result of lubricating the glass fabric with polyurethane varnish, the drift of fine fibers is removed.

The following examples of layered insulators according to the invention for small and medium rotating machines, i.e. in the range of miniature motors up to motors up to 600 kV power usable in temperature classes F and H, represent some possible combinations:

Example

A: compacted aramid cardboard, specific weight 930 kg/m ³ , thickness 0.13 mm

B: non-alkaline glass fabric lubricated with canvas weave, thickness 0.10 mm

C: polyurethane binder

By layering component Z on both sides of component A using binder C, a layered insulation of type BCACB with a thickness of 0.37 mm is created.

Example 2

A: compacted aramid cardboard, specific weight 1,030 kg/m ³ , thickness 0.18 mm

B: polyester mat, specific weight 820 kg/m ³ , thickness 0.08 mm

C: alkyl epoxy binder

The layering is of the BCACB type with a thickness of 0.38 millimeters.

Example 3

A: compacted aramid cardboard, specific weight 1,030 kg/m ³ , thickness 0.18 mm

B: polyester mat, specific weight 850 kg/m ³ , thickness 0.10 mm

C: modified epoxy-based binder.

By layering component Z on one side of component A, a BCA-type insulator is created, 0.30 millimeters thick.

3

Table 1

Physical and dielectric properties Marking

Features

Resistance to along (P) tear in (N) across (n) Stiffness in (Nj P n Specific thermal conductivity 24°C in (Wm ^_1 k ⁴ ) 43.5°C Differential voltage 23 °C add. st. in (kV) after bending 180°C add. st. after bending Fortress Border P in tension in (MPaj n Elongation, % P n The purpose of the invention is to obtain them layered insulation made of synthetic fiberboard and thermal

resistant layer for groove insulation in thermal class F and H economically advantageous

208 405 402 151 210 201 111 110 — 200 200 _. 0.182 — 0.140 — 8.2 8.3 7.25 4.6 7.1 — 7.8 8.2 7.2 4.4 7.0 124 111 110 117 48 48 5 22 23 4 16 19

method, by increasing the proportion of more economical components while maintaining the insulating properties of the material.

SUBJECT

Claims (3)

6 12 3 233914 3 Table 1 Physical and dielectric properties Labeling Properties Resistance to (P) tear at (N) across (n) Stiffness at (N) P n Specific thermal conductivity 24 ° C at (Wm_1k4) 43,5 ° C Breakout Tension 23 ° C Suppl. st. v (kV) after bending 180 ° C dod. Bending Strength P Tensile Strength v (MPaj n Elongation,% P n) The object of the present invention is to provide a laminated synthetic arterial insulation and a heat-resistant layer for grooved insulation in thermal class F and H in an economical way. 111 110 - 200 200 _. 0.182 - 0.140 - 8.2 8.3 7.25 4.6 7.1 - 7.8 8.2 7.2 4.4 7.0 124 111 110 117 48 48 5 22 23 4 16 19 by increasing the proportion of more economical components while preserving the insulating properties of the material. 1. A heat-insulated laminated thermal insulation class F and H, characterized in that it comprises a ridge a-ramid cardboard of 0.05 to 0.25 mm, preferably 0.18, which is laminated on one or both sides with a protective material. an organic or inorganic fiber fracture by means of an organic binder which does not degrade to 180 ° C. THE INVENTION 2. A layered insulator according to claim 1, wherein the protective layer is a glass fabric, lubricated with a heat-resistant or synthetic mat. paper or glass paper. 3. A laminate according to claim 1, wherein the heat-resistant binder is a polyurethane, an alkylepoxide or a silicone adhesive.