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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces Methods of Test for the Determination of Surface Insulation Resistance and Lamination Factor of Electric Sheet and Strip (GB/T 2522-2007); the following changes have been made with respect to GB 2522-2007:
——the standard name is changed to Methods of Test for The Determination of Coating Insulation Resistance and Coating Adhesion of Electrical Strip and Sheet from Methods of Test for the Determination of Surface Insulation Resistance and Lamination Factor of Electric Sheet and Strip;
——the coating insulation resistance test circuit diagram is modified;
——the coating insulation resistance test circuit diagram is modified;
——the test method in which the total area of 10 contacts is 1000mm2 is added;
——the requirements on the total current of 10 contacts are modified;
——the calculation for coefficient of interface resistance is added;
——the repeatability and reproducibility requirements on coating insulation resistance test are added;
——coating adhesion levels are added.
This standard has been redrafted and modified adoption of Magnetic Materials - Part 11: Method of Test for the Determination of Surface Insulation Resistance of Magnetic Sheet and Strip (IEC 60404-11:2012), and it is not equivalent to IEC 60404-11:2012.
This standard is proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of the standard replaced by this standard are as follows:
——GB/T 2522-1981, GB/T 2522-1988, GB/T 2522-2007.
Methods of Test for the Determination of Coating Insulation Resistance and Coating Adhesion of Electrical Strip and Sheet
1 Scope
This standard specifies methods of test for the determination of coating insulation resistance and coating adhesion of electrical strip and sheet.
This standard is applicable to the test for the determination of surface insulation resistance and interface resistance of non-oriented and oriented electrical strip and sheet, as well as the test for the determination of insulation coating adhesion of non-oriented and oriented electrical strip and sheet.
2 Test of Coating Insulation Resistance
2.1 Principle of measurement
The principle of the measurement is based on, and includes, the method originally described by Franklin which characterizes only one coated surface at a time.
The arrangement of the apparatus is shown in Figure 1. Ten metallic contacts of fixed area are applied to one coated surface of the sheet, under specified conditions of voltage and pressure. The effectiveness of the surface insulation is assessed by the measurement of the currents through the 10 contacts.
Keys:
1——d.c. power supply;
2——computer;
3——display;
4——10 contacts;
5——drill;
6——test specimen;
7——insulation coating.
Figure 1 Arrangement of Apparatus for the Measurement of Surface Insulation Resistance
Contacts are fed from a d.c. power supply, as shown in Figure 2, and the voltage between the 5×(1±1%)Ω resistor and the drill is stabilized at 500×(1±0.5%)mV over a current range of 0~1A. The two twist drills perform the function of current return contacts with the metallic substrate of test specimen.
2.2 Test specimen
2.2.1 Each test specimen shall be formed from a single sheet or length of strip. The width and length of the test specimen shall be respectively greater than the width and length of the contact assembly described in 2.3. This measurement is destructive; the test specimen can only be used once.
2.2.2 To obtain a representative result, test specimens shall be taken from the full sheet width. The test specimen surface shall be clean, flat and neat, and be free from any spot and scratch.
2.3 Apparatus
2.3.1 Contact assembly
The test specimen is pressed between a plate and the contact assembly. The contact assembly consists of 10 vertically-mounted metallic rods which move axially against springs in amounting block. These 10 contact rods are normally arranged in two rows. However, for convenience these 10 contacts can be arranged in one row. Each rod shall be provided with a contact button of bronze or other suitable material (for example, stainless steel) and shall be electrically insulated from the mounting frame.
Note 1: articulation of contact buttons improves contact by compensating for minor misalignments.
Each of the 10 contacts shall have a contact area of 64.5×(1±1%)mm2 or 100×(1±1%)mm2, giving a total area for the 10 contacts of 645×(1±1%)mm2 or 1000×(1±1%)mm2, and the recommended total area is 645 mm2.
Note 2: only the total area of 645 mm2 is adopted in international standard. Generally, the testing results of corresponding contacts of two total areas are not comparable.
Electrical contact with the substrate of the test specimen shall be achieved by means of two spring-loaded twist drills of about 3 mm diameter which pierce the insulation coating
2.3.2 Power supply
A d.c. power supply capable of maintaining a stabilized voltage of 500mV across the electrodes at the maximum load current of 1.0A shall be used.
2.3.3 Current measurement
The current flowing through the contact buttons shall be measured with an uncertainty of ± 2% or better. This can be achieved by inserting an ammeter in the supply to the contact buttons, at a point outside the connection to the stabilizing circuit.
The electrical arrangements of the stabilizing circuit and current measurement system are shown in Figure 2.
Keys:
1——Stabilized d.c. power supply;
2——drills;
3——contact;
4——output voltage;
5——feedback voltage;
6——test specimen.
Figure 2 Arrangement of Circuit
2.3.4 Determination of applied force
The total force applied by all of the contacts pressing on the test specimen shall be determined by any suitable means with an uncertainty of ±5 % or better.
2.4 Calibration
The calibration of the equipment should be checked in three ways:
a) The contacts and drills shall be applied to a clean copper sheet at nominal testing pressure. The total current passing through the 10 electrodes shall be 1.0×(1±3%)A. If this is not the case, the contacts shall be checked for cleanliness and the drills checked for sharpness and contact resistance.
b) Carbon paper pressed onto white paper by the contacts at nominal testing pressure shall give a set of even smudges free from signs of force concentration. Pressure measurement sheets that could indicate applied pressure as colour density variations can be used instead of the carbon paper and white paper.
c) Standard resistors of 0.1 Ω, 1 Ω, 10 Ω and 100 Ω connected between the drills and each contact button in turn shall be used to show that the stabilization is adequate and that the required current levels can be achieved.
2.5 Measuring procedure
2.5.1 The test specimen shall be positioned between the baseplate and the 10 contacts and a force of 1290×(1±5%)N for the total area of 645 mm2 or 2000×(1±5%)N for the total area of 1000mm2 shall be gradually applied. This corresponds to a pressure of 2 N/mm2.
2.5.2 The stabilized voltage supply shall be applied to the electrodes and the total current shall be recorded or by computer.
2.5.3 If the insulation quality of a single surface is to be evaluated in the test, 10 readings shall be taken using the 10 contacts on 10 separate representative areas of the sheet or on 10 test specimens.
2.5.4 If the insulation quality of both surfaces is to be jointly evaluated in the test then ten applications of the contacts shall be made to each surface on five separate representative areas or test specimens. The same area of the test specimen shall not be used to test both sides.
2.6 Calculation of coating insulation resistance
2.6.1 Coefficient of surface insulation resistance
The coefficient of surface insulation resistance shall be determined by inserting the 10 values of the current flowing through the 10 electrodes in parallel (either all from one surface or five from each of the two coated surfaces) in Formula (1).
(1)
Where,
C——the coefficient of surface insulation resistance, in Ω·mm2/side or Ω·cm2/side;
A——the total area of the 10 contacts, in mm2 or cm2;
U——the voltage applied to the contacts and 5 Ω resistors, in V;
R——the resistance in series with each contact, equal to 5 Ω, in Ω;
IA——the measured total electrode current (10 values), in A;
2.6.2 Coefficient of interface resistance
Value RA represented by coefficient of interface resistance is the resistance of the two surfaces of the product, it is theoretically twice of the coefficient of surface insulation resistance (C).
The coefficient of interface resistance shall be determined by inserting the 10 values of the current flowing through the 10 electrodes in parallel (five from each of the two coated surfaces, 10 values in total) in Formula (2).
(2)
Where,
RA——the coefficient of interface resistance, in Ω·mm2/sheet or Ω·cm2/sheet;
A——the total area of the 10 contacts, in mm2 or cm2;
U——the voltage applied to the contacts and 5 Ω resistors, in V;
R——the resistance in series with each contact, equal to 5 Ω, in Ω;
IA——the measured total electrode current (10 values), in A;
2.7 Repeatability and reproducibility
Even when equipment, operation and maintenance, etc. are in good condition, their repeatability and reproducibility are greatly affected by the surface properties of the test specimen when testing coating insulation resistance by Franklin's method. In actual test, it is very difficult evaluate the repeatability and reproducibility of the method.
2.8 Test report
Unless otherwise agreed, the test report shall include:
a) The number of this standard;
b) The identification and status of test specimen and coating;
c) The total area of the contacts of the selected equipment, 645 mm2 or 1000 mm2;
d) Test result: the coefficient of surface insulation resistance or the coefficient of interface resistance.
3 Test Method for Coating Adhesion
3.1 Apparatus
Brass cylinders with smooth surface and in diameter of 10mm, 20mm and 30mm respectively and the tolerance of -0.5 mm~+0.1 mm are used.
3.2 Test specimen
Representative test specimens shall be taken in the direction parallel to the rolling direction, not be less than 40mm from the edge of steel strip (sheet), without damaging test specimen coating. Dimensions of test specimen: 30 mm±0.2 mm in width and 280 mm~320 mm in length. The supplier and the purchaser can negotiate about special requirements, if any.
Foreword i 1 Scope 2 Test of Coating Insulation Resistance 3 Test Method for Coating Adhesion
ICS 77.040.99 H 21 中华人民共和国国家标准 GB/T 2522—2017 代替GB/T 2522—2007 电工钢带(片)涂层绝缘电阻和附着性测试方法 Methods of test for the determination of coating insulation resistance and coating adhesion of electrical strip and sheet (IEC 60404-11：2012，Magnetic materials—Part 11：Method of test for the determination of surface insulation resistance of magnetic sheet and strip，NEQ) 2017-07-12发布 2018-04-01实施 中华人民共和国国家质量监督检验检疫总局 中国国家标准化管理委员会 发布 前言 本标准按照GB/T 1.1—2009给出的规则起草。 本标准代替GB/T 2522—2007《电工钢片(带)表面绝缘电阻、涂层附着性测试方法》，与GB/T 2522—2007相比，主要变化如下： ——标准名称由《电工钢片(带)表面绝缘电阻、涂层附着性测试方法》改为《电工钢带(片)涂层绝缘电阻和附着性测试方法》； ——修改了涂层绝缘电阻测试电路图； ——删除了涂层绝缘电阻测试的方法B； ——增加了10个触头总面积为1 000 mm2的测试方法； ——修改了10个触头的总电流的规定； ——增加了层间电阻系数的计算； ——增加了涂层绝缘电阻测试重复性和再现性要求； ——增加了涂层附着性级别。 本标准使用重新起草法参考IEC 60404-11：2012《磁性材料 第11部分：测定磁性钢板带表面绝缘电阻的测试方法》编制，与IEC 60404-11：2012的一致性程度为非等效。 本标准由中国钢铁工业协会提出。 本标准由全国钢标准化技术委员会(SAC/TC 183)归口。 本标准起草单位：武汉钢铁股份有限公司、宝山钢铁股份有限公司、首钢总公司、冶金工业信息标准研究院。 本标准主要起草人：刘集中、沈杰、向前、石建锐、王玉婕、胡守天、唐灵、龚坚、刘宝石、魏海丽、周星、邱忆。 本标准所代替标准的历次版本发布情况为： ——GB/T 2522—1981、GB/T 2522—1988、GB/T 2522—2007。 电工钢带(片)涂层绝缘电阻和附着性 测试方法 1 范围 本标准规定了电工钢带(片)涂层绝缘电阻和附着性的测试方法。 本标准适用于无取向和取向电工钢带(片)表面绝缘电阻和层间电阻的测试，以及无取向和取向电工钢带(片)绝缘涂层附着性的测试。 2涂层绝缘电阻的测试 2.1 测量原理 采用只能进行单涂层测量的富兰克林法。 设备电路示意图如图1所示。在规定的电压和压强下，将10个固定面积的金属触头压在钢板的一个涂层表面上。通过测量流过10个触头的电流来评定表面绝缘涂层的效能。
