GB/T 20632.2-2022 (GB/T20632.2-2022, GBT 20632.2-2022, GBT20632.2-2022) & related versions
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Vulcanized fibre for electrical purposes - Part 2: Methods of test
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GB/T 20632.2-2022
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GB/T 20632.2-2022: PDF in English (GBT 20632.2-2022)
GB/T 20632.2-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.035.10
CCS K 15
GB/T 20632.2-2022 / IEC 60667-2:2020
Vulcanized Fiber for Electrical Purposes – Part 2: Methods of Test
(IEC 60667-2:2020, IDT)
ISSUED ON: JULY 11, 2022
IMPLEMENTED ON: FEBRUARY 01, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 6
4 General Notes on Tests ... 6
4.1 Conditioning ... 6
4.2 Drying ... 6
4.3 Result ... 7
5 Thickness ... 7
6 Density ... 7
6.1 Apparent density ... 7
6.2 Density in liquid (specific gravity) ... 8
7 Tensile Strength and Elongation ... 8
8 Flexural Strength ... 9
9 Water Absorption ... 9
10 Electric Strength up to and including 3 mm in Thickness ... 10
11 Arc Resistance ... 10
12 Chloride Content ... 10
13 Ash Content ... 10
14 Flexibility (Bending) ... 11
15 Moisture Content ... 13
16 Internal Ply Adhesion ... 13
17 Shrinkage ... 14
Vulcanized Fiber for Electrical Purposes – Part 2: Methods of Test
1 Scope
This Document gives methods of test for vulcanized fiber sheets for electrical purposes.
Material made by combining with an adhesive several thicknesses of vulcanized fiber is not
covered by this Document.
Materials which conform to this Document meet established levels of performance. However,
the selection of a material by a user for a specific application is based on the actual requirements
necessary for adequate performance in that application and not based on this Document alone.
Safety warning: It is the responsibility of the user of the methods contained or referred to in
this Document to ensure that they are used in a safe manner.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in this Document. For the dated documents, only the versions with the dates
indicated are applicable to this Document; for the undated documents, only the latest version
(including all the amendments) is applicable to this Document.
GB/T 1411-2002 Dry, Solid Insulating Materials - Resistance Test to High-Voltage, Low-
Current Arc Discharges (IEC 61621:1997, IDT)
GB/T 19264.2-2013 Pressboard and Presspaper for Electrical Purposes - Part 2: Methods
of Test (IEC 60641-2:2004, MOD)
NOTE: There are no technical differences between the quoted contents from GB/T 19264.2-2013
and that from IEC 60641-2:2004.
ISO 178:2019 Plastics – Determination of Flexural Properties
NOTE: GB/T 9341-2008 Plastics – Determination of Flexural Properties (ISO 178:2001, IDT)
ISO 287:2017 Paper and Board – Determination of Moisture Content of a Lot – Oven-
Drying Method
NOTE: GB/T 462-2008 Paper, Board and Pulp - Determination of Moisture Content of Analytical
Sample (ISO 287:1985, ISO 638:1978, MOD)
4.3 Result
As a general rule, the central value is reported as the result. When agreed between parties, the
mean value may be reported. This shall be noted in the test report.
5 Thickness
The thickness shall be determined as Clause 5 in GB/T 19264.2-2013.
Deviations from GB/T 19264.2-2013:
--- 10 spots alongside the circumference of the test piece shall be measured and the mean
value of them shall be obtained.
6 Density
6.1 Apparent density
The test shall be carried out on three conditioned test pieces; one determination is made on each
of the three test pieces.
Use rectangular test pieces of an area no less than 100 cm2 and determine the mass to an
accuracy of 10−4 × mass of the test piece.
Make two measurements of the length and two of the width of each test piece to an accuracy of
0.1 mm at points at least 12 mm from the corners.
Determine the thickness by making eight measurements as indicated in Clause 5 and calculate
the mean value of the measurements.
Calculate the apparent density ρ (the mass to volume ratio) as Formula (1):
Where:
ρ - apparent density, in g/cm3;
m - the mass, in g;
s - the mean of the eight thickness measurements, in cm;
l - the mean of the two length measurements, in cm;
w - the mean of the two width measurements, in cm.
Report all three values. The central value shall be taken as the result.
6.2 Density in liquid (specific gravity)
Use rectangular test pieces of an area not less than 16 cm2 with the original thickness of the
material. Determine the mass of the test piece weighed to an accuracy of 10−4 × mass of the test
piece in air and in liquid of known density at the temperature of test.
The density in liquid is calculated by the Formula (2):
Where:
ρ – density in liquid, in g/cm3;
m1 – mass of test piece in air, in g;
m2 – mass of test piece, in liquid, in g;
x – density of liquid, in g/cm3.
NOTE: Suitable liquids are: water, transformer oil, alcohol and other solvent.
7 Tensile Strength and Elongation
Tensile strength and elongation shall be measured according to the method described in Clause
7 of GB/T 19264.2-2013.
Deviations from GB/T 19264.2-2013:
--- five measurements shall be made on the test pieces (20 ± 2) mm by 180 mm cut from
both directions of test specimens;
--- the test length shall initially be (100 ± 0.5) mm;
--- the load being applied at a rate of 60 mm/min and continued, the test piece breaks.
10 Electric Strength up to and including 3 mm in Thickness
Electric strength shall be determined by the method specified in Clause 20 of GB/T 19264.2-
2013.
Deviations from GB/T 19264.2-2013:
--- five measurements are made on the test pieces square of approximately 100 mm and of
thickness of the sheet test;
--- the electrodes shall consist of two metal cylinders with the edges rounded to give a radius
of (3.0 ± 0.2) mm. One electrode shall be (25 ± 1) mm in diameter and approximately 25
mm high. The other electrode shall be (75 ± 1) mm in diameter;
--- the test pieces shall be dried in accordance with 4.2;
--- measure and record the thickness of each test piece.
The electric strength in kilovolts per millimeter is calculated by the Formula (4):
Where:
E - the electric strength, in kV/mm;
V - the breakdown voltage, in kV;
t - the thickness of the test piece after drying, in mm.
11 Arc Resistance
Arc resistance to rupture shall be determined as specified in GB/T 1411-2002.
12 Chloride Content
Any recognized method of determining chloride ions in a water extract is permitted.
13 Ash Content
The amount of residue of material left after incineration of the material in the "as received"
condition shall be determined according to the method described in Clause 14 of GB/T 19264.2-
2013. The mass of the test piece shall be 5 g. Three determinations shall be made.
14 Flexibility (Bending)
The flexibility is determined using the measuring principle depicted in Figure 1.
A test piece is placed between the two jaws of the measuring device as shown in Figure 2. The
jaws are closed until the test piece cracks or shows signs of rupture.
The flexibility tester is a small vise with jaws about 50 mm wide with small projections about
25 mm from the top edge of jaws against which the ends of specimens are placed. The movable
jaw is equipped with a pointer and scale arrangement to indicate the decimal parts for each
complete revolution of the vise handle. A dial gauge graduated in 0.01 mm units is placed in
the back of the vise handle to indicate the jaw movement for a part of a complete revolution of
the handle.
Measure the distance between the inner span of jaws by a dial gauge.
Three measurements of each direction are made on the test pieces approximately 25 mm by 50
mm cut from both directions of specimens.
Open the jaws of the bend tester to about 20 mm. Carefully insert a test piece (25 ± 1) mm ×
(50 ± 1) mm between the jaws in a slightly arched position brown side up. It may be necessary
to hold the test piece down but care should be taken not to place moist fingers on the expected
point of rupture.
Close the jaws of the tester at a constant rate of (3 ± 1) mm/s. Observe the test piece closely
and stop turning the handle; read the dial gauge as soon as a crack or sign of rupture is noted in
the test piece.
The flexibility in millimeters is calculated by the Formula (5):
Where:
f - the flexibility, in mm;
d - the distance, in mm;
t - the thickness of the test piece, in mm.
15 Moisture Content
Moisture content of material, as received, shall be measured according to the method described
in ISO 287:2017.
The mass of the specimen shall be at least 5 g. Three test specimens shall be taken. The method
consists of weighing the test specimen in the as received condition and after drying. The drying
time shall be as described in Table 2.
The moisture content in percentage is calculated by the Formula (6):
Where:
α - the moisture content, in %;
m1 - the mass of the test specimen in before drying, in g;
m2 - the mass of the test specimen after drying, in g.
16 Internal Ply Adhesion
A ply adhesion testing jig (Figure 3) which can be attached to the tensile testing apparatus as
described in Clause 7 shall be used.
Three measurements are made respectively for three times on the test pieces with a width of
(25 ± 1) mm or (12.5 ± 1) mm and a length of at least 300 mm. The longer dimension of test
pieces shall be aligning with the machine direction of specimen.
First, the test piece shall be peeled off along the direction of 25mm width by hand, and the
peeled place shall be as close as possible to the middle layer of the test piece. After peeling off
completely in the 25mm width direction, continue to peel off about 80mm along the 300mm
length direction. Then, the test piece shall be put into the interlayer peel strength test fixture
(see Figure 3), and the two ends that have been peeled off are clamped in the jaws of the tester
so that they are at right angles to the unpeeled part. The holding distance is (125±5) mm. After
starting up, the test fixture shall move at a constant speed of (300±10) mm/min, and the peeling
length is about 75mm.
Record the force.
The internal ply adhesion is expressed in Newtons per meter and calculated by the Formula (7):
......
| Standard ID | GB/T 20632.2-2022 (GB/T20632.2-2022) | | Description (Translated English) | Vulcanized fibre for electrical purposes - Part 2: Methods of test | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | K15 | | Classification of International Standard | 29.035.10 | | Word Count Estimation | 12,134 | | Date of Issue | 2022-07-11 | | Date of Implementation | 2023-02-01 | | Drafting Organization | Guilin Saimeng Testing Technology Co., Ltd., Wuxi Xinhongtai Electrical Technology Co., Ltd., Guangxi Nanbaote Electric Manufacturing Co., Ltd., Guilin Electrical Apparatus Research Institute Co., Ltd., CRRC Zhuzhou Electric Locomotive Research Institute Co., Ltd., Guangdong Yisheng Testing Co., Ltd. , Zhejiang Huiri Environmental Testing Co., Ltd., Jiangsu Meixida Technology Co., Ltd., Xi'an Kaijinzhe Testing Co., Ltd., Guangdong Yidu Technology Co., Ltd., Zhejiang Rujing Technology Co., Ltd., Zaozhuang Hengxiang Paper Products Co., Ltd., Guangdong Cheng Xin Technology Co., Ltd., Dongguan Ruijing Electric Technology Co., Ltd., Guangdong Tehua Technology Co., Ltd., Shaanxi Jinyoubang Technology Co., Ltd., Yiwu Jinglong Mould Co., Ltd., Shaanxi Runzheng Testing Technology Co., Ltd. | | Administrative Organization | National Technical Committee for Standardization of Insulating Materials (SAC/TC 51) | | Proposing organization | China Electrical Equipment Industry Association | | Issuing agency(ies) | State Administration for Market Regulation, National Standardization Administration |
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