CS233496B1 - Flat insulating material for low voltage electrical machines - Google Patents

Abstract

The invention relates to the issue of insulating materials of temperature class F for insulating systems of low-voltage electrical machines. The insulating material according to the invention has, in comparison with the insulators produced so far, higher thermoplasticity, is more dimensionally stable, is more flame-resistant and, after hardening, forms a compact whole with the winding of the electrical machine. The essence of the invention lies in the fact that it consists of at least one layer in an unhardened state of flexible thermal insulator with a surface weight of at least 120 g/m, formed on the basis of thermal paper and glass fabric, pre-impregnated with a pre-polymerized binder or a combination of binders from the group of thermosetting plastics with a resin component content of 0 to 90%. bonded with at least one layer of pre-hardened prepreg with a surface weight of 40 to 400 g/m2, formed on the basis of glass fabric and a binder or a combination of binders from the group of thermosetting substances with a resin component content of 10 to 90%. The use of the invention is considered especially in the manufacture of insulation systems of overloaded electrical machines, operating in modes of frequent starting, reversing and under deteriorated operating conditions

Description

BACKGROUND OF THE INVENTION The present invention relates to insulating materials for low voltage electrical machines utilized in higher temperature classes, in particular temperature class F, in particular insulating materials for insulating slot, position and interfacial parts of low voltage electrical machines.

At present, flat insulating materials formed by a combination of polyester mats with polyethylene terephthalate foils are used to insulate the winding grooves and inter-phase insulation, even though they do not actually meet the technical parameters that would guarantee their sufficient service life in temperature class F. Their main drawback is their small dimension at operating temperature and loss of mechanical properties, especially ductility. These insulations in common low-voltage electrical machine failure conditions (overload until the overcurrent trip can be repeated several times) are less resistant to overloading of the wire harness, especially at the output of the slot, often causing failure of the motor insulation system due to short circuit. Disadvantages of these insulations eSte is increased by the use of some impregnating lacquers which are necessary for the insulation system of low-voltage electric machines, but which still worsen the insulating properties, since after impregnating and gluing the groove insulation with the impregnant on the stator or rotor stack. insulation, respectively. its shrinking, it is cracking. Cracks formed in the groove portion increase the risk of electrical breakage between the winding and the frame. As a result of the loss of ductility during operational aging, the slot insulation at the point of exit from the machine's magnetic circuit breaks or breaks and ceases to perform its insulating function. The interfacial and positional insulations of the insulating materials are stratified and cracked upon loss of aging elongation, thereby disrupting the insulating system in the most exposed parts of the winding cells. Insulation of electrical low-voltage machines with aramid paper and insulations combined with a capton partially removes these deficiencies, while these insulations are resistant to commonly used impregnants, but when insulating the groove parts with these insulating materials, they arise during manual filling or filling. during winding of the winding, its inter-operation and final shaping of the deformation (folding, cutting) of the groove insulation at the outlet of the groove and in the operation of low-voltage electric machines, premature destruction of the insulation occurs. When interfacial insulation is inserted, deformation occurs, which is the greater the more complicated the shape of the winding. Due to the stiffness of the interfacial insulation, the winding fronts are imperfectly copied when inserted, as a result of which cavities and gaps are created, and the heat dissipation from the low-voltage electrical machine winding is impaired.

The above-mentioned disadvantages of the prior art overcome the present invention of sheet insulating material for low-voltage electrical machines, which consists in that it consists of at least one layer in an unconfirmed state of a flexible core insulator of at least 120 g / m basis weight. , pre-impregnated with a prepolymerised binder or a combination of binders from the group of thermosetting plastics containing a bituminous component of 10 to 90 bonded with at least one layer of pre-cured prepreg of 40 to 400 g / m 2 components 10 to 90%.

By using the insulating materials according to the invention for insulating electrical low-voltage machines, mechanical deformations and imperfect adhesion of the groove insulations to the winding and the frame are eliminated. Insulation material has higher temperature resistance, thermoplasticity, compared to manufactured insulators, it is dimensionally stable, resists to a higher degree of flame and after hardening it forms a compact unit with winding. The insulating material according to the invention is more suitable for interfacial insulation than the materials used hitherto and also because its surface is rougher, which prevents the winding faces from slipping. The insulating system of the low voltage electrical machines with the insulating material applied according to the invention can be impregnated with conventional, impregnating varnishes and if the insulating material is partially porous, it allows perfect pre-impregnation of the entire insulating system.

The following examples illustrate the nature of the invention in direct application:

EXAMPLE

The sheet lzolating material was prepared by gluing a glass fabric foil and bilayer epoxy binder having an epoxy equivalent of 180 to 400e in the first layer and a softening point of 30 to 50 ° C in the first layer and an epoxy equivalent of 150 to 500 in the second layer Not more than 40 to 60 ° C, basis weight 220 g / m ² and epoxy prepreg

Weighing 330 g / m 2 with a bitumen content of 38% and a bitumen binder flow at

MPA and 170 ° C 17%. The components were bonded at a pressure of 0.5 to 1 MPa, a temperature of 165 ° C for 5 to 15 s. The resulting product was perfectly glued and flexible. The insulating material was cut to the desired groove size. Prior to insertion of the groove insulation into the grooves of the reversed asynchronous motor, the groove outlets were lined with 0.20 mm wired sheet insulation, which is of exclusive auxiliary nature and prevents damage to the sheet insulator during insertion and shaping of the winding. After inserting the winding into the grooves, the reversed asynchronous motor was pre-dried before impregnation. As the temperature rises, the lysing material softened, softened, mechanical stresses were removed, and the insulator adapted to its winding shape. The entire lysis system was solidified by adjusting the temperature to 150 ° C for 6 hours. The reversed asynchronous motor, with a winding temperature of 180 ° C, had functional interphase and groove insulation even after 1,000 hours of operation.

Basic physico-mechanical and dielectric properties of the insulating material used before and after curing at 200 ° C for 30 minutes:

Thickness (mm)

Stiffness (N) not confirmed confirmed

Breakdown voltage (HF) not confirmed Hardened

Breakdown voltage hardened at 130 ° C (kV)

155 ° C 200 ° C 250 ° C

Thermoplasticity at 265 ° C (hr)

Shrinkage (%) during temperature aging at 160 ° C after 130 days

220 days

310 days at 200 ° C after 130 days

220 days

310 days

0.35

126

9.1

10.5 θ, 7

8.2

7.0

6.5

0.6

By bonding the foil insulation material as in Example 1 and the polyamide prepreg 2 with a basis weight of 187 g / m and a bitumen content of 35% and a bitumen binder flow at 10 MPa and 170 ° C at 15% pressure and temperature as in Example 1, physical-mechanical and dielectric properties before and after curing at 200 ° C for 30 minutes:

Thickness (mm) 0.28

Stiffness (N) not confirmed 22 confirmed 74

Breakdown voltage (kV) not confirmed 9.5 confirmed 10.5

Breakdown voltage hardened at 130 ° C (kV) 9.8

155 ° C 7.0

200 ° C 6.6

250 ° C 5.5

Thermoplasticity> 8 at 265 ° C (hr)

Shrinkage (%) during temperature aging at 160 ° C after 130 days 0

220 days 0

310 days 0.5 at 200 ° C after 130 days 0

220 days 0

310 days 0

The use of the solution according to the invention comes into consideration, in particular, in the construction of insulating systems of overloaded electrical machines operating in frequent triggering, reversing and in degraded operating conditions.

Claims (1)

233496 4 -Height (mm) '0.28 Stiffness (N) Unhardened 22 Hardened 74 Breakdown Tension (kV) Unhardened 9.5 Hardened 10.5 Hardening Strength Hardened at 130 ° C (kV) 9.8 155 ° C 7 0 200 ° C 6.6 250 ° C 5.5 Thermoplasticity> 8 at 265 ° C (hr) Shrinkage (%) during temperature aging at 160 ° C after 130 days 0 220 days 0 310 days 0.5 at 200 ° C after 30 days 0 220 days 0 310 days 0 The use of the solution according to the invention is particularly suitable for the production of insulated systems of overloaded electrical machines operating in six trigger, reversing, and degraded operating modes. OBJECT OF THE INVENTION A sheet-like insulating material for low-voltage electrical machines, characterized in that it comprises at least one layer in an uncontrolled state of a flexible plastic insulating material having a mass of at least 120 g / m 2, formed on the basis of paper and glass-fiber pre-impregnated with a prepolymerized binder or a combination of reactive group binders with a content of a nutrient component of 10 to 90% bonded to at least one layer of pre-cured prepreg having a basis weight of 40 to 400 g / m, formed on a glazed fabric and binders or combinations of binders from the group of thermosetting agents with a nutrient content of 10 to 90%, Severografia, np, MOST Price 2,40 Kčs