This part of GB12802 specifies the classification and requirements of polyester films for electrical insulation. This part of GB12802 applies to films made from polyethylene terephthalate by casting and balanced biaxial orientation. GB 12802.2-2004 Films for electrical insulation Part 2: Polyester films for electrical insulation GB12802.2-2004 Standard download decompression password: www.bzxz.net

ICS 29. 035. 20
National Standard of the People's Republic of China
GB12802.2—2004
Replaces GB13950--1992
Film for electrical insulation
Part 2: Polythylene terephthalate film used for eletrical insulation(IEC 60674-3-2.1992,Part 3.Specifications for individual relerials-Sheet 2.Reguirernenis for balanced biaxially oriented polyethyleneterephthalate(PET)films used for electrical insulation, MOD) 2004-02-04 issued
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China China National Standards Administration
2004-08-01 implementation
The three indicators of tensile strength, electrical strength and electrical weakness in Table 3 of this part are mandatory. GB12802 "Films for electrical insulation" is divided into three parts: Part 1: Polypropylene film for capacitors, .. Part 2: Polyester film for electrical insulation; --- Part 3: Polyimide film.
GB/T 12802.2--2004
This part is the second part of GB12802. The revision adopts IFC60674-3-2:1992 (Specification for plastic films for electrical use Part 3: Specification for individual materials Part 2: Requirements for balanced biaxially oriented poly(terephthalic acid) alkyd (PET) films for electrical insulation) (English version). The main differences between this part and EC60674-3-2 are as follows: Added 25μm and 150μm thickness specifications of polyester films; Added the provisions on the shortest segment length;
Added IEC61074:1991 Test method for determination of heat of fusion, melting point, heat of crystallization and crystallinity of electrical insulating materials by differential scanning calorimetry;
-Specified the specific index of melting point, and added in the note of Table 2 The melting point can also be added by DSC method, according to the provisions of IEC61074, the index is to be determined;
Classification According to domestic requirements, type 1 is 6020 and 6021. Type 2 is 6022; the naming clause is cancelled.
This part replaces GB13950-1992.
This part differs from (GB13950-1992) as follows: the number of joints has been increased;
The "film end face film height" in Table 3 of GB13950-1992 is changed to "the difference between the film width and the film width excluding the core";
... The shrinkage rate is adjusted to the size change:
The indicators of tensile strength, elongation at break, relative dielectric constant, dielectric loss factor and density are adjusted; - 125μm, The index value of the low-frequency electrical strength of the 150μm thickness specification film; the electrode system for testing the power frequency electrical strength is specified; - the melting point is added. The DSC method can also be used according to the provisions of IEC61074. The index is to be determined: the word "recommended" in Chapter 5 and Chapter 6 of CB13950-1992 is cancelled, and the "rapid rise" is changed to "voltage rise speed 500V/s\,
This part is proposed by the China Electrical Equipment Industry Association. This part is under the jurisdiction of the National Technical Committee for Standardization of Insulating Materials. The drafting units of this part are Sichuan Dongfang Insulating Materials Co., Ltd. and Guilin Power Capacitor General Factory. The main drafters of this part: Yu Yafang, Li Zhaolin, Li Zhiping. The previous versions replaced by this part are: - GB13950-1992,
1 Fan Pu| |tt||Films for electrical insulation
Part 2: Polyester films for electrical insulation
GB/T12802.2—2004
This part of GB12802 specifies the classification and requirements of polyester films for electrical insulation (hereinafter referred to as films). This part of GB12802 applies to films made from cast sheets and balanced biaxially oriented surfaces of polyethylene terephthalate. 2 Normative references
The clauses in the following documents become the clauses of this part through reference to this part of GB12802. For dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this part. However, parties to agreements based on this part are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest versions apply to this part. GB/T1354 Test method for plastic film for electrical use (GB/T135411992, neqIEC60674-2.1988) GB/T13542 General requirements for plastic film for electrical use (GB/T13542-1992, neqIEC60674-1:1980) IEC61074:1991 Test method for heat of fusion, melting point, heat of crystallization and crystallization temperature of electrical insulating materials by differential scanning calorimetry
3 Classification
Films are divided into two types and models according to their characteristics and uses, as shown in Table 1. 1 Classification and models of films
4 General requirements
Properties and uses
Transparent films for general purposes
Opaque films for general purposes
Films for capacitor dielectrics
The film material should be made of polyethylene terephthalate, have a biaxially oriented structure with approximately balanced orientation and meet the requirements of GB/T13542.
For some applications, requirements for adding additives (such as pigments, dyes) to the material may be proposed. Unless otherwise specified, additives should not affect any performance requirements of the type of film listed. 5 Dimensions
5. 1 Thickness
The film thickness shall be in accordance with the provisions of Chapter 4 of GB/T 13541-1992. Films with a thickness of 15 um or less shall be in accordance with the provisions of 4.1.2 or 4.2 of GB/T 13541-1992, and films with a thickness of more than 15 μm shall be in accordance with the provisions of 4.1.1 or 4.2 of GB/T13541-1992.
This part of GB12802 does not make any requirements on thickness, but the preferred thicknesses are as follows: 2 μm, 3 μm, 3.5 μm.5 μm, 6 μm.8 μm, 10 μm.12 μm, 15 μm, 19 μm, 23 μm, 25 μm, 36 μm, 50 μm.75μm100um, 125μm.150μm.190μm, 250μm300μm350μmGB/T 12802.22004
Unless otherwise specified in the supply contract, the measured thickness shall be within the range of ±10% of the nominal value. 5.2 Width
The film width shall be in accordance with Chapter 6 of GB/T13541-1992. Due to different application conditions, it is impossible to give the preferred width specification. The width specification shall be determined by negotiation between the supply and demand parties. Except for the film for making elliptical wedges, which stipulates that when the width is less than 25mm, a deviation of -0.3mm~0mm can be selected, the width deviation of other films shall comply with the requirements of 5.2 in GB/T13542-1992. 6 Performance
6.1 Performance requirements not related to barrier
Performance requirements not related to thickness are shown in Table 2.
Capsule 2 Performance requirements for all models
Melting point"
Dielectric constant
Dielectric loss factor
6 020,6022
48Hz~62Hz
48H2-62H2
Volume resistivity
Surface resistivity
Electrolytic corrosion
Dimensional stability under high overflow
Under tension
Under pressure
1390±10
1400±10
≥256
3. 2±0. 3
3. 2±0, 3
≤3×10-3
GB/T13541 (Chapter/Article)
21 Mesh adjustment method
21' Wire drawing method
Use sinking and floating method or density gradient column to test, use potassium iodide aqueous solution, take the median of three test values ​​as the test result,Keep 4 significant figures. This method is only applicable to films with a thickness greater than 12 μm. b
The LSC method can also be used in accordance with the provisions of IEC61074, and the indicators are to be determined. c The AC electric field strength applied to the sample during the test is not greater than 10 V/μm. According to the requirements of the test instrument, the method of multi-film combination can be used. The number of samples is three, and the median of the three test values ​​is taken as the test result. d The test conditions are 23℃, 50%RH, and after 24h exposure, the test current is (100=10)V for those with a thickness greater than 10μm; for those with a thickness less than 10μm, it is 10 V. Type 1 According to the requirements of the test instrument, the method of multi-film combination can be used. The electrification time is 2 min. The number of samples is three. The median of the three tests is taken as the test result.
The test conditions of the tensile wire method are 40℃, 93%RFI, and the exposure cycle is 06 h. 6.2 Performance requirements related to thickness
Performance requirements related to thickness are shown in Table 3. Properties
Elongation
(in either direction)
Minimum value
Elongation at break
Rate (in either direction)
Minimum value
Dimensional change
(in either direction)
Shrinkage)
Electrical strength
Electrical spurious point
Table 3 Performance requirements related to thickness
>15 μm~≤100 μm
>100 μm~≤250 μm>250 μm
See Table 4
See Table 5
See Table 6
Note: Tensile strength, electrical strength and electrical weakness are mandatory indicators. No requirement for films with a thickness of less than m.
, the stretching speed is 100mm/min, and the distance between the markings is 100mm. 110
CB/T12802.2--2004
GB/T 13541
(Chapter/Article)
22(15c℃15min)
1 and 2
Apply 6mm diameter electrodes. Films with a thickness of ≤100m should be tested in air with a voltage increase rate of 600V/s. Materials with a thickness of less than 100pm should be tested in transformer oil. The arithmetic mean of 10 tests is taken as the test result, and the test area is 10 m. The test voltage is calculated according to the nominal thickness of the film at 200 V/μm. Electric strength (AC test), for all models Table 4
Nominal thickness/urr
Electrical strength
Minimum value/(V/μn)
GB/T 13641(year/article)
Use 6 mm1 diameter electrode.
In air
GB/T 12802.2—2004
Nominal thickness/
Fall 4(continued)
Electrical strength
Note, the performance index values ​​of non-recommended preferred nominal series are obtained by interpolation Minimum value/(V/μm)
GB/T13541(chapter/article)
Use Gmm diameter electrode.
In transformer oil
Table 5 Electric strength (DC test) Applicable only to Type 2 Nominal thickness/μm
Minimum breakdown voltage
Median value/kv
21. Less than 2 of the results are allowed
to be lower than the following specified value/kv
Note: The performance index values ​​for non-recommended preferred nominal thicknesses are obtained by interpolation. Table 6 Electrical weakness of 6022-type film
Nominal thickness/pm
12 and above
One of the 21 results is allowed to be lower than
the following specified value/kV
Number of weaknesses/(number/n)
Note 1. The electrical weakness is measured according to Chapter 19 of GB/T 13541-1992, and the number of weaknesses measured when the test voltage is applied at 200 V/μm according to the nominal thickness of the film should not exceed the value given in this document. Note 2: The performance index values ​​of non-recommended preferred nominal thicknesses are obtained by interpolation. 6.3 Other properties
6.3.1 Long-term heat resistance
Long-term heat resistance should be tested according to Chapter 33 of GB/T 1354]1992. The instrument is applicable to type 1 film. TI≥130 Fire point standard: tensile strength remains 10% of the initial value. TI≥115; End point standard: tensile strength maintains 50% of the initial value. Those who meet either of these two points can be regarded as meeting the requirements of this part. During the aging process, the moisture content in the aging oven without load should be 9.5 g/m3 ~ 12.5 g/m. The recommended aging temperature is 140℃, 160℃, and 180℃. 6.3.2 Combustion performance
No requirements.
7 Membrane properties for all models
7.1 Roll diameter/film length
This part of GB 12802 has no requirements for the roll diameter or the length of the rolled film. These should meet the contract requirements. 7.2 Windability
According to Chapter 7 of GB/T 13541-1992, the performance requirements are shown in Table 7, 7.2.1 For film rolls with a width of less than 150 mm, follow 7.2 of GB/T13541-1992. Table 7 Film Windability
Drift/Arm
Sag (tension 5MPa)
7.2.2 For film rolls with a width of 150 mm and above, perform according to 7.3 of GB/T 13541-1992. GB/T 12802.2-2004
Unit: mm
The required extension to achieve the required drift/arm and sag limit should not exceed 0.1%. There is no such requirement for films with a thickness greater than 36 mm.
7.3 Number of joints and shortest length of section
The number of joints and the shortest length of section per roll shall be determined by both parties. When no negotiation is made, the number of joints and the shortest length of section per roll shall be shown in Table 8. Table 8 Number of joints and shortest length
Number of joints/piece
Thickness of film/e
Film width
Width 50I
Outer diameter-≤250 mm
Outer diameter: 250mm
Outer diameter<250 tnn~<450 mm
Shortest length/m
The difference between the film width measured in accordance with Chapter 6 of GB/T 13541-1992 and the width of the film roll excluding the core should not be greater than the provisions of Table 9.
Table 9 Film roll width
Nominal roll width
150---300
The preferred core is 76mm and 152mm.
Requirement (maximum difference)
Unit is mm2 Performance requirements related to thickness
Performance requirements related to thickness are shown in Table 3. Properties
Elongation
(in either direction)
Minimum value
Elongation at break
Rate (in either direction)
Minimum value
Dimensional change
(in either direction)
Shrinkage)
Electrical strength
Electrical spurious point
Table 3 Performance requirements related to thickness
>15 μm~≤100 μm
>100 μm~≤250 μm>250 μm
See Table 4
See Table 5
See Table 6
Note: Tensile strength, electrical strength and electrical weakness are mandatory indicators. No requirement for films with a thickness of less than m.
, the stretching speed is 100mm/min, and the distance between the markings is 100mm. 110
CB/T12802.2--2004
GB/T 13541
(Chapter/Article)
22(15c℃15min)
1 and 2
Apply 6mm diameter electrodes. Films with a thickness of ≤100m should be tested in air with a voltage increase rate of 600V/s. Materials with a thickness of less than 100pm should be tested in transformer oil. The arithmetic mean of 10 tests is taken as the test result, and the test area is 10 m. The test voltage is calculated according to the nominal thickness of the film at 200 V/μm. Electric strength (AC test), for all models Table 4
Nominal thickness/urr
Electrical strength
Minimum value/(V/μn)
GB/T 13641(year/article)
Use 6 mm1 diameter electrode.
In air
GB/T 12802.2—2004
Nominal thickness/
Fall 4(continued)
Electrical strength
Note, the performance index values ​​of non-recommended preferred nominal series are obtained by interpolation Minimum value/(V/μm)
GB/T13541(chapter/article)
Use Gmm diameter electrode.
In transformer oil
Table 5 Electric strength (DC test) Applicable only to Type 2 Nominal thickness/μm
Minimum breakdown voltage
Median value/kv
21. Less than 2 of the results are allowed
to be lower than the following specified value/kvwww.bzxz.net
Note: The performance index values ​​for non-recommended preferred nominal thicknesses are obtained by interpolation. Table 6 Electrical weakness of 6022-type film
Nominal thickness/pm
12 and above
One of the 21 results is allowed to be lower than
the following specified value/kV
Number of weak points/(number/n)
Note 1. The electrical weakness is measured according to Chapter 19 of GB/T 13541-1992, and the number of weak points measured when the test voltage is applied at 200 V/μm according to the nominal thickness of the film should not exceed the value given in this document. Note 2: The performance index values ​​of non-recommended preferred nominal thicknesses are obtained by interpolation. 6.3 Other properties
6.3.1 Long-term heat resistance
Long-term heat resistance should be tested according to Chapter 33 of GB/T 13541-1992. The instrument is applicable to type 1 film. TI≥130 Fire point standard: tensile strength remains 10% of the initial value. TI≥115; End point standard: tensile strength maintains 50% of the initial value. Those who meet either of these two points can be regarded as meeting the requirements of this part. During the aging process, the moisture content in the aging oven without load should be 9.5 g/m3 ~ 12.5 g/m. The recommended aging temperature is 140℃, 160℃, and 180℃. 6.3.2 Combustion performance
No requirements.
7 Membrane properties for all models
7.1 Roll diameter/film length
This part of GB 12802 has no requirements for the roll diameter or the length of the rolled film. These should meet the contract requirements. 7.2 Windability
According to Chapter 7 of GB/T 13541-1992, the performance requirements are shown in Table 7, 7.2.1 For film rolls with a width of less than 150 mm, follow 7.2 of GB/T13541-1992. Table 7 Film Windability
Drift/Arm
Sag (tension 5MPa)
7.2.2 For film rolls with a width of 150 mm and above, perform according to 7.3 of GB/T 13541-1992. GB/T 12802.2-2004
Unit: mm
The required extension to achieve the required drift/arm and sag limit should not exceed 0.1%. There is no such requirement for films with a thickness greater than 36 mm.
7.3 Number of joints and shortest length of section
The number of joints and the shortest length of section per roll shall be determined by both parties. When no negotiation is made, the number of joints and the shortest length of section per roll shall be shown in Table 8. Table 8 Number of joints and shortest length
Number of joints/piece
Thickness of film/e
Film width
Width 50I
Outer diameter-≤250 mm
Outer diameter: 250mm
Outer diameter<250 tnn~<450 mm
Shortest length/m
The difference between the film width measured in accordance with Chapter 6 of GB/T 13541-1992 and the width of the film roll excluding the core should not be greater than the provisions of Table 9.
Table 9 Film roll width
Nominal roll width
150---300
The preferred core is 76mm and 152mm.
Requirement (maximum difference)
Unit is mm2 Performance requirements related to thickness
Performance requirements related to thickness are shown in Table 3. Properties
Elongation
(in either direction)
Minimum value
Elongation at break
Rate (in either direction)
Minimum value
Dimensional change
(in either direction)
Shrinkage)
Electrical strength
Electrical spurious point
Table 3 Performance requirements related to thickness
>15 μm~≤100 μm
>100 μm~≤250 μm>250 μm
See Table 4
See Table 5
See Table 6
Note: Tensile strength, electrical strength and electrical weakness are mandatory indicators. No requirement for films with a thickness of less than m.
, the stretching speed is 100mm/min, and the distance between the markings is 100mm. 110
CB/T12802.2--2004
GB/T 13541
(Chapter/Article)
22(15c℃15min)
1 and 2
Apply 6mm diameter electrodes. Films with a thickness of ≤100m should be tested in air with a voltage increase rate of 600V/s. Materials with a thickness of less than 100pm should be tested in transformer oil. The arithmetic mean of 10 tests is taken as the test result, and the test area is 10 m. The test voltage is calculated according to the nominal thickness of the film at 200 V/μm. Electric strength (AC test), for all models Table 4
Nominal thickness/urr
Electrical strength
Minimum value/(V/μn)
GB/T 13641(year/article)
Use 6 mm1 diameter electrode.
In air
GB/T 12802.2—2004
Nominal thickness/
Fall 4(continued)
Electrical strength
Note, the performance index values ​​of non-recommended preferred nominal series are obtained by interpolation Minimum value/(V/μm)
GB/T13541(chapter/article)
Use Gmm diameter electrode.
In transformer oil
Table 5 Electric strength (DC test) Applicable only to Type 2 Nominal thickness/μm
Minimum breakdown voltage
Median value/kv
21. Less than 2 of the results are allowed
to be lower than the following specified value/kv
Note: The performance index values ​​for non-recommended preferred nominal thicknesses are obtained by interpolation. Table 6 Electrical weakness of 6022-type film
Nominal thickness/pm
12 and above
One of the 21 results is allowed to be lower than
the following specified value/kV
Number of weak points/(number/n)
Note 1. The electrical weakness is measured according to Chapter 19 of GB/T 13541-1992, and the number of weak points measured when the test voltage is applied at 200 V/μm according to the nominal thickness of the film should not exceed the value given in this document. Note 2: The performance index values ​​of non-recommended preferred nominal thicknesses are obtained by interpolation. 6.3 Other properties
6.3.1 Long-term heat resistance
Long-term heat resistance should be tested according to Chapter 33 of GB/T 13541-1992. The instrument is applicable to type 1 film. TI≥130 Fire point standard: tensile strength remains 10% of the initial value. TI≥115; End point standard: tensile strength maintains 50% of the initial value. Those who meet either of these two points can be regarded as meeting the requirements of this part. During the aging process, the moisture content in the aging oven without load should be 9.5 g/m3 ~ 12.5 g/m. The recommended aging temperature is 140℃, 160℃, and 180℃. 6.3.2 Combustion performance
No requirements.
7 Membrane properties for all models
7.1 Roll diameter/film length
This part of GB 12802 has no requirements for the roll diameter or the length of the rolled film. These should meet the contract requirements. 7.2 Windability
According to Chapter 7 of GB/T 13541-1992, the performance requirements are shown in Table 7, 7.2.1 For film rolls with a width of less than 150 mm, follow 7.2 of GB/T13541-1992. Table 7 Film Windability
Drift/Arm
Sag (tension 5MPa)
7.2.2 For film rolls with a width of 150 mm and above, perform according to 7.3 of GB/T 13541-1992. GB/T 12802.2-2004
Unit: mm
The required extension to achieve the required drift/arm and sag limit should not exceed 0.1%. There is no such requirement for films with a thickness greater than 36 mm.
7.3 Number of joints and shortest length of section
The number of joints and the shortest length of section for each roll shall be determined by both parties. When no negotiation is made, the number of joints and the shortest length of section for each roll shall be shown in Table 8. Table 8 Number of joints and shortest length
Number of joints/piece
Thickness of film/e
Film width
Width 50I
Outer diameter-≤250 mm
Outer diameter: 250mm
Outer diameter<250 tnn~<450 mm
Shortest length/m
The difference between the film width measured in accordance with Chapter 6 of GB/T 13541-1992 and the width of the film roll excluding the core should not be greater than the provisions of Table 9.
Table 9 Film roll width
Nominal roll width
150---300
The preferred core is 76mm and 152mm.
Requirement (maximum difference)
Unit is mm1 Long-term heat resistance
Long-term heat resistance shall be tested according to Chapter 33 of GB/T 1354]1992. The instrument is applicable to type 1 film. TI ≥ 130 Burning point standard: tensile strength maintains 10% of the initial value. TI ≥ 115; End point standard: tensile strength maintains 50% of the initial value. Those who meet either of these two point standards can be regarded as meeting the requirements of this part. During the aging process, the humidity content in the aging oven without load should be 9.5 g/m3 ~ 12.5 g/m. The recommended aging temperature is 140℃, 160℃, and 180℃. 6.3.2 Combustion performance
No requirements.
7 Film properties for all types
7.1 Roll diameter/film length
This part of GB 12802 has no requirements for the roll diameter or the length of the rolled film. These should meet the contract requirements. 7.2 Windability
According to Chapter 7 of GB/T 13541-1992, performance requirements are shown in Table 7. 7.2.1 For film rolls with a width of less than 150 mm, according to 7.2 of GB/T 13541-1992. Table 7 Windability of Film
Shift/Arm
Sag (tension 5 MPa)
7.2.2 For film rolls with a width of 150 mm or more, according to 7.3 of GB/T 13541-1992. GB/T 12802.2-2004
Unit is mm
The extension required to achieve the required shift/arm and sag limits should not be greater than 0.1%. There is no such requirement for films with a thickness greater than 36 mm.
7.3 Number of joints and shortest length
The number of joints and the shortest length of each roll shall be determined by both parties. If no negotiation is made, the number of joints and the shortest length of each roll shall be shown in Table 8. Table 8 Number of joints and shortest length
Number of joints/piece
Film thickness/e
Film width
Width 50I
Outer diameter-≤250 mm
Outer diameter: 250mm
Outer diameter<250 tnn~<450 mm
Shortest length/m
The difference between the film width measured in Chapter 6 of GB/T 13541-1992 and the width of the film roll excluding the core shall not be greater than the provisions of Table 9.
Table 9 Film roll width
Nominal roll width
150---300
The preferred tube core is 76mm and 152mm.
Requirement (maximum difference)
Unit is millimeter1 Long-term heat resistance
Long-term heat resistance shall be tested according to Chapter 33 of GB/T 1354]1992. The instrument is applicable to type 1 film. TI ≥ 130 Burning point standard: tensile strength maintains 10% of the initial value. TI ≥ 115; End point standard: tensile strength maintains 50% of the initial value. Those who meet either of these two point standards can be regarded as meeting the requirements of this part. During the aging process, the humidity content in the aging oven without load should be 9.5 g/m3 ~ 12.5 g/m. The recommended aging temperature is 140℃, 160℃, and 180℃. 6.3.2 Combustion performance
No requirements.
7 Film properties for all types
7.1 Roll diameter/film length
This part of GB 12802 has no requirements for the roll diameter or the length of the rolled film. These should meet the contract requirements. 7.2 Windability
According to Chapter 7 of GB/T 13541-1992, performance requirements are shown in Table 7. 7.2.1 For film rolls with a width of less than 150 mm, according to 7.2 of GB/T 13541-1992. Table 7 Windability of Film
Shift/Arm
Sag (tension 5 MPa)
7.2.2 For film rolls with a width of 150 mm or more, according to 7.3 of GB/T 13541-1992. GB/T 12802.2-2004
Unit is mm
The extension required to achieve the required shift/arm and sag limits should not be greater than 0.1%. There is no such requirement for films with a thickness greater than 36 mm.
7.3 Number of joints and shortest length
The number of joints and the shortest length of each roll shall be determined by both parties. If no negotiation is made, the number of joints and the shortest length of each roll shall be shown in Table 8. Table 8 Number of joints and shortest length
Number of joints/piece
Film thickness/e
Film width
Width 50I
Outer diameter-≤250 mm
Outer diameter: 250mm
Outer diameter<250 tnn~<450 mm
Shortest length/m
The difference between the film width measured in Chapter 6 of GB/T 13541-1992 and the width of the film roll excluding the core shall not be greater than the provisions of Table 9.
Table 9 Film roll width
Nominal roll width
150---300
The preferred tube core is 76mm and 152mm.
Requirement (maximum difference)
Unit is millimeter
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