A method for calculating the pressure maintaining time of high-voltage motor stator coil main insulation VPI

Abstract

The application relates to the technical field of stator coil, and particularly discloses a calculation method of VPI pressure maintaining time of high-voltage motor stator coil main insulation, which divides the thickness of the stator coil main insulation into multiple range sections, and calculates the VPI pressure maintaining time according to the aspect ratio of the linear part of the stator coil and the wire of the stator coil. The application combines the influence of different main insulation thicknesses, different linear part lengths and different wire aspect ratios of the stator coil on the VPI pressure maintaining time, meets the insulation performance of the stator coil main insulation after VPI impregnation and hot-pressing curing, reduces the VPI defects of the stator coil main insulation, reduces the quality loss caused by the unqualified coil insulation performance, and ensures the stable reliability of long-term safe operation of the unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stator coil, more particularly, to a calculation method of VPI pressure maintaining time of high-voltage motor stator coil main insulation. BACKGROUND

[0002] As a core component of the motor, the stator coil main insulation VPI (Vacuum Pressure Impregnation) is a key technology in the manufacture of high-voltage motors, and the VPI process determines the amount and size of the internal air gap of the stator coil main insulation, as well as the electrical performance of the coil main insulation, which plays a crucial role in the running life and safety reliability of the motor insulation.

[0003] At present, the conventional method for producing VPI stator coil insulation of high-voltage motors in domestic and foreign motor manufacturers is as follows: after the coil wire is solidified and formed, different layers of little mica tape are semi-laminated on the surface of the coil wire according to the high or low rated voltage of the motor. In order to improve the production efficiency, usually dozens of stator coils with different voltage grades, different insulation thicknesses, different lengths and shapes are put into the impregnation tank at the same time for VPI. After the coil is put into the impregnation tank, the impregnation tank is vacuumed, the impregnating resin is input into the impregnation tank, a certain pressure is applied to the resin in the impregnation tank, and the pressure is maintained for a period of time, then the pressure in the impregnation tank is unloaded, the VPI resin is pumped back, and the coil is taken out for heat pressing and solidification.

[0004] The traditional VPI process method of the stator coil main insulation has many problems. In the actual production and manufacturing process of the coil, dozens of coils with different sizes, shapes and voltage grades are impregnated under the same VPI parameters, and the coil main insulation VPI impregnation is often poor or the impregnation time is too long. When the coil main insulation is thick, the straight part is long, and the ratio of the height to the width of the wire is large, the impregnating resin does not completely penetrate into the inner layer of the mica tape, the resin between the layers of the mica tape is not uniformly filled, the coil main insulation is empty, the air gap is too much, the interlayer adhesion is poor, and the insulation performance is unqualified, such as large coil dielectric loss increment, low power frequency breakdown voltage, short electrical aging life, etc. When the coil main insulation is thin, the straight part is short, and the ratio of the height to the width of the wire is small, the small size coil impregnated with the large size coil will move the mica flake in the main insulation mica tape due to the too long impregnation time, resulting in unqualified insulation performance such as low power frequency breakdown voltage and short electrical aging life. The phenomenon of insulation batch rejection, economic loss and product delivery cycle delay caused by the VPI defects of the stator coil main insulation occurs from time to time in domestic and foreign motor manufacturers. SUMMARY

[0005] The technical problem solved by the present application is to provide a calculation method of VPI pressure maintaining time of high-voltage motor stator coil main insulation.

[0006] The solution adopted by the present application to solve the technical problem is:

[0007] The calculation method of VPI pressure maintaining time of high-voltage motor stator coil main insulation divides the stator coil main insulation thickness into multiple range sections, and calculates the VPI pressure maintaining time according to the stator coil straight part and the high-width ratio of the stator coil wire.

[0008] In some possible implementation manners,

[0009] The stator coil main insulation thickness is d, and the multiple range sections include d≤4mm, 4mm<d<6mm, and d≥6mm.

[0010] In some possible implementation manners,

[0011] The stator coil straight part is L, and the stator coil straight part is divided into two range sections, and the two range sections include L<5m and L≥5m.

[0012] In some possible implementation manners,

[0013] When the stator coil main insulation thickness d≤4mm, the VPI pressure maintaining time t1 of the stator coil main insulation is

[0014]

[0015] Wherein, C1 is 2.1-2.5h, C2 is 0.2-0.3 / mm, and C3 is 0.16-0.25 / m, and the values are determined according to the motor operation characteristics and the insulation life requirement.

[0016] In some possible implementation manners,

[0017] When the stator coil main insulation thickness 4mm<d<6mm and the stator coil straight part L<5m, the VPI pressure maintaining time t2 of the stator coil main insulation is

[0018]

[0019] Wherein, C4 is 0.16-0.19 / mm, C5 is 0.2-0.28 / m, and C6 is 0.22-0.3h, and the values are selected according to the motor operating characteristics and insulation life requirements.

[0020] In some possible embodiments,

[0021] When the stator coil main insulation thickness d is greater than or equal to 6mm and / or the stator coil straight line part L is greater than or equal to 5m, the stator coil main insulation VPI pressure maintaining time is t3,

[0022]

[0023] Wherein, C7 is 0.15-0.18 / mm, C8 is 0.22-0.28 / m, and C9 is 0.25-0.32h, and the values are selected according to the motor operating characteristics and insulation life requirements.

[0024] In some possible embodiments,

[0025] When multiple types of stator coil main insulation are subjected to VPI at the same time, the multiple types of stator coil main insulation all satisfy the condition that the stator coil main insulation thickness d is less than 6mm and the stator coil straight line part L is less than 5m;

[0026] The formula (1) or the formula (2) is used for calculation respectively;

[0027] The longer time in the calculation results is selected as the VPI pressure maintaining time of the batch.

[0028] In some possible embodiments,

[0029] When multiple types of stator coil main insulation are subjected to VPI at the same time, the multiple types of stator coil main insulation all satisfy the condition that the thickness d is greater than or equal to 6mm or the stator coil straight line part length L is greater than or equal to 5m, the formula (3) is used for calculation respectively, and the longer time in the calculation results is selected as the VPI pressure maintaining time of the batch.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The present application combines different stator coil main insulation thicknesses, different straight line part lengths, and different wire height-width ratios, and satisfies the insulation performance of all different sizes and shapes of stator coil main insulation after VPI impregnation heat pressing and curing, reduces the VPI defects of the stator coil main insulation, reduces the quality loss caused by unqualified coil insulation performance, ensures the timely and quality delivery of the stator coil, and ensures the stable reliability of long-term safe operation of the unit.

[0032] The application avoids the insulation defects of the large-size stator coil main insulation, such as poor impregnation, air void, large dielectric loss increment, low power frequency breakdown voltage, and short electric aging life, by calculating and analyzing the parameters of the stator coil main insulation thickness, the coil straight portion length, and the coil wire aspect ratio, and by optimizing the VPI pressure maintaining time, thereby greatly reducing the quality loss caused by the unqualified stator coil insulation performance. DETAILED DESCRIPTION

[0033] In the present application, unless otherwise explicitly specified and limited, the terms such as "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or can be integrated; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. The "first", "second" and similar words mentioned in the present application do not represent any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "a" and the like do not represent a quantity limit, but represent the existence of at least one. In the implementation of the present application, the association relationship of the associated objects is described as "and / or", which means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" is two or more. For example, multiple positioning columns refer to two or more positioning columns. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] The present application will be described in detail below.

[0035] A calculation method of VPI pressure maintaining time of high-voltage motor stator coil main insulation, the stator coil main insulation thickness is divided into multiple range sections, and the VPI pressure maintaining time is calculated according to the high-width ratio of the stator coil straight portion and the stator coil wire.

[0036] In some possible implementation manners,

[0037] The stator coil main insulation thickness is d, and the multiple range sections include d≤4mm, 4mm<d<6mm, and d≥6mm.

[0038] In some possible implementation manners,

[0039] The stator coil straight portion is L, and the stator coil straight portion is divided into two range sections, and the two range sections include L<5m and L≥5m.

[0040] In some possible implementation manners,

[0041] When the thickness d of the main insulation of the stator coil is less than or equal to 4 mm, the VPI pressure maintaining time t1 of the main insulation of the stator coil is determined according to the following formula (1):

[0042]

[0043] In the formula, C1 is 2.1-2.5 h, C2 is 0.2-0.3 / mm, and C3 is 0.16-0.25 / m, which are determined according to the operating characteristics of the motor and the insulation life requirement.

[0044] It should be noted that when multiple types of main insulation of the stator coil are subjected to VPI simultaneously, the thickness d of the multiple types of main insulation of the stator coil is less than or equal to 4 mm, such as 2 mm, 3 mm, and 4 mm, the corresponding time is calculated respectively, and all the times are compared, and the longest time is taken as the VPI pressure maintaining time of the VPI of the multiple types of main insulation of the stator coil.

[0045] In some possible implementations,

[0046] When the thickness d of the main insulation of the stator coil is greater than 4 mm and less than 6 mm, and the linear part L of the stator coil is less than 5 m, the VPI pressure maintaining time t2 of the main insulation of the stator coil is determined according to the following formula (2):

[0047]

[0048] In the formula, C4 is 0.16-0.19 / mm, C5 is 0.2-0.28 / m, and C6 is 0.22-0.3 h, which are determined according to the operating characteristics of the motor and the insulation life requirement.

[0049] In some possible implementations,

[0050] When the thickness d of the main insulation of the stator coil is greater than or equal to 6 mm and / or the linear part L of the stator coil is greater than or equal to 5 m, the VPI pressure maintaining time t3 of the main insulation of the stator coil is determined according to the following formula (3):

[0051]

[0052] In the formula, C7 is 0.15-0.18 / mm, C8 is 0.22-0.28 / m, and C9 is 0.25-0.32 h, which are determined according to the operating characteristics of the motor and the insulation life requirement.

[0053] In some possible implementations, when multiple types of main insulation of the stator coil are subjected to VPI simultaneously, the multiple types of main insulation of the stator coil all satisfy the condition that the thickness d of the main insulation of the stator coil is less than 6 mm and the linear part L of the stator coil is less than 5 m, and the formula (1) or the formula (2) is used for calculation respectively.

[0054] The longer time in the calculation result is selected as the VPI pressure maintaining time of the batch.

[0055] The various types of stator coil main insulation described herein satisfy the condition that the stator coil main insulation thickness d < 6 mm and the stator coil straight portion length L < 5 m, i.e., when the various types are three types, including Type One, Type Two and Type Three; in Type One, the stator coil main insulation thickness is 4 mm and the stator coil straight portion length is 4 m, in Type Two, the stator coil main insulation thickness is 4 mm and the stator coil straight portion length is 3 m, and in Type Three, the stator coil main insulation thickness is 3 mm and the stator coil straight portion length is 2 m.

[0056] The formula (1) and the formula (2) are respectively applied to the three types before VPI to obtain six groups of time, the six groups of time are compared, and the longest time is selected as the VPI pressure maintaining time.

[0057] In some possible embodiments, when the various types of stator coil main insulation are subjected to VPI at the same time, the various types of stator coil main insulation are all of thickness d ≥ 6 mm or stator coil straight portion length L ≥ 5 m, the formula (3) is respectively applied to the four types to obtain four groups of time, the four groups of time are compared, and the longest time is selected as the VPI pressure maintaining time.

[0058] For example, the various types include Type Four, Type Five, Type Six and Type Seven; in Type Four, the stator coil main insulation thickness is 7 mm; in Type Five, the stator coil main insulation thickness is 8 mm; in Type Six, the stator coil straight portion length is 5 m; and in Type Seven, the stator coil straight portion length is 6 m; the formula (3) is respectively applied to the four types to obtain four groups of time, the four groups of time are compared, and the longest time is selected as the VPI pressure maintaining time.

[0059] Example 1

[0060] A batch of various types of stator coil main insulation is subjected to VPI at the same time, the batch includes four types, and all satisfy the condition that the stator coil main insulation thickness d ≤ 4 mm, the formula (1) is applied to the calculation result, as shown in Table 1.

[0061]

[0062] Table 1

[0063] According to the calculation result in Table 1, the VPI pressure maintaining time of the batch of various types of stator coil main insulation is 6.5 h, or the pressure maintaining is performed twice, each time for 3.25 h.

[0064] Example 2

[0065] A batch of various types of stator coil main insulation is simultaneously subjected to VPI, the batch contains five types, all of which meet the requirements of d < 6 mm for the thickness of the stator coil main insulation and L < 5 m for the length of the straight portion of the stator coil, and the calculation results according to formula (1) or (2) are shown in Table 2.

[0066]

[0067] Table 2

[0068] According to the calculation results in Table 2, the VPI pressure maintaining time for the batch of various types of stator coil main insulation is 9.8 h, or the pressure is maintained for two times, each time for 4.9 h.

[0069] Example 3

[0070] A batch of various types of stator coil main insulation is simultaneously subjected to VPI, the batch contains four types, all of which meet the requirements of d ≥ 6 mm for the thickness of the stator coil main insulation or L ≥ 5 m for the length of the straight portion of the stator coil, and the calculation results according to formula (3) are shown in Table 3.

[0071]

[0072]

[0073] Table 3

[0074] According to the calculation results in Table 3, the VPI pressure maintaining time for the batch of various types of stator coil main insulation is 18.2 h, or the pressure is maintained for two times, each time for 9.1 h.

[0075] Example 4

[0076] For the stator coil main insulation with a thickness of 5.6 mm, a straight length of 3.6 mm, and a coil height-width ratio of 5.2, the original impregnation process parameters are used for VPI pressure maintaining for 5 h, and the impregnation process parameters according to the proposal of the application are used for pressure maintaining for 2*4.5 h, and the impregnation parameters are shown in Table 4.

[0077]

[0078] Table 4

[0079] The insulation performance of the stator coil after hot-pressing and curing is shown in Table 5.

[0080]

[0081] Table 5

[0082] From the stator coil insulation performance test data of Table 5, it can be seen that the stator coil after being hot-pressed for 5 hours using the original impregnation process parameters has a large initial dielectric loss, dielectric loss increment, partial discharge value, and a low instantaneous power frequency breakdown voltage value, indicating that the stator coil main insulation is poorly impregnated and has a non-dense insulation; the stator coil after being hot-pressed for 2*4.5 hours using the impregnation process parameters of the application has a small initial dielectric loss, dielectric loss increment, partial discharge value, and a high instantaneous power frequency breakdown voltage value, indicating that the stator coil main insulation is well impregnated, dense, and has excellent electrical performance.

[0083] The application is not limited to the foregoing specific embodiments. The application extends to any novel one, or any new combination, of the characteristics disclosed in this specification, as well as to any novel method or process disclosed in any of the steps or any new combination.

Claims

1. A method for calculating the VPI pressure holding time of high voltage motor stator coil main insulation, characterized in that, The stator coil main insulation thickness is divided into multiple range sections, and the VPI pressure maintaining time is calculated according to the stator coil straight line part and the aspect ratio of the stator coil wire; The stator coil main insulation thickness is d, and the multiple range sections include d≤4mm, 4mm<d<6mm, and d≥6mm; When the stator coil main insulation thickness d is less than or equal to 4 mm, the stator coil main insulation VPI pressure maintaining time , （1）； wherein, takes a value of 2.1-2.5, takes a value of 0.2-0.3, takes a value of 0.16-0.25 according to the motor operating characteristics and insulation life requirements, L is the length of the straight part of the stator coil, and K is the height-width ratio of the stator coil wire.

2. The method for calculating the VPI pressure maintaining time of the high-voltage motor stator coil main insulation according to claim 1, characterized in that, The stator coil straight line part is divided into two range sections, including L<5m and L≥5m.

3. The method for calculating the VPI pressure maintaining time of the high-voltage motor stator coil main insulation according to claim 2, characterized in that, When the stator coil main insulation thickness 4mm < d < 6mm and the stator coil straight portion L < 5m, the stator coil main insulation VPI pressure maintaining time is , （2）； wherein, 0.16-0.19, 0.2-0.28, 0.22-0.3, according to the motor operating characteristics and insulation life requirements.

4. The method for calculating the VPI pressure maintaining time of the high-voltage motor stator coil main insulation according to claim 2, characterized in that, When the stator coil main insulation thickness d≥6mm and / or the stator coil straight section L≥5m, the stator coil main insulation VPI pressure maintaining time is , （3）; wherein, 0.15-0.18, 0.22-0.28, 0.25-0.32, according to the motor operating characteristics and insulation life requirements.

5. The method for calculating the VPI pressure maintaining time of the high-voltage motor stator coil main insulation according to claim 3, characterized in that, When multiple types of stator coil main insulation are simultaneously subjected to VPI, the multiple types of stator coil main insulation all satisfy the conditions of stator coil main insulation thickness d<6mm and stator coil straight line part L<5m; Respective calculation is performed by using formula (1) or formula (2); The longer time in the calculation results is selected as the VPI pressure maintaining time of the batch.

6. The method for calculating the VPI pressure maintaining time of the high-voltage motor stator coil main insulation according to claim 4, characterized in that, When multiple types of stator coil main insulation are simultaneously subjected to VPI, the multiple types of stator coil main insulation all have thickness d≥6mm or stator coil straight line part length L≥5m, and respective calculation is performed by using formula (3), and the longer time in the calculation results is selected as the VPI pressure maintaining time of the batch.

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