GB/T 32288-2020 PDF in English
GB/T 32288-2020 (GB/T32288-2020, GBT 32288-2020, GBT32288-2020)
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Name of Chinese Standard | Status |
| GB/T 32288-2020 | English | 260 |
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Electrical steel core for power transformers
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| GB/T 32288-2015 | English | 759 |
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Electrical steel core for power transformers
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Standards related to (historical): GB/T 32288-2020
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GB/T 32288-2020: PDF in English (GBT 32288-2020) GB/T 32288-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.40
H 53
Replacing GB/T 32288-2015
Electrical Steel Core for Power Transformers
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Ordering Content ... 5
4 Model Representation Method ... 6
5 Technical Requirements ... 6
6 Test Method ... 10
7 Inspection Rules ... 12
8 Marking, Packaging, Transportation and Storage ... 12
Appendix A (Normative) Test Method of Core Geometric Characteristics ... 13
Electrical Steel Core for Power Transformers
1 Scope
This Standard specifies the model representation method, technical requirements, test methods,
inspection rules, marking, packaging, transportation and storage of electrical steel cores for
power transformers.
This Standard applies to electrical steel laminated core (hereinafter referred to as core) for
power transformers.
2 Normative References
The following documents are essential to the application of 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 1094.1 Power Transformers – Part 1: General
GB/T 1094.10 Power Transformers – Part 10: Determination of Sound Levels
GB/T 2521.2 Cold-Rolled Electrical Steel Delivered in the Fully-Processed State - Part 2:
Grain-Oriented Steel Strip (Sheet)
GB/T 6451 Specification and Technical Requirements for Oil-Immersed Power
Transformers
GB/T 10228 Specification and Technical Requirements for Dry-Type Power Transformers
JB/T 3837 Identification Method of Transformers Product Type
3 Ordering Content
The contract or order for ordering according to this Standard shall at least include the following
contents:
a) Transformer model;
b) The number of this Standard;
c) Core assembly drawing and core lamination drawing;
d) Frequency (Hz);
e) Low voltage (V);
f) Number of low-voltage turns (turns);
g) Core no-load loss (W);
h) Core no-load current (%);
i) Delivery status;
j) Sound level;
k) Quantity (set);
l) Other requirements.
4 Model Representation Method
The model of the core follows the representation method of the power transformer model
specified in JB/T 3837.
5 Technical Requirements
5.1 Core insulation
5.1.1 Under the condition that the relative humidity of the air is lower than 85%, the insulation
value of the core with a voltage level of 35kV and below shall meet the following requirements:
a) Dry-type transformer ≥ 5MΩ;
b) Oil-immersed transformer ≥ 1MΩ.
5.1.2 Under the condition that the relative humidity of the air is lower than 85%, the insulation
value of the core with a voltage level of 35kV above shall meet the following requirements:
a) Core-to-ground insulation ≥ 0.5MΩ;
b) The insulation between the core oil channels is ≥0.5MΩ.
5.2 No-load loss, no-load current and sound level
The no-load loss, no-load current and sound level of the core shall meet the technical
Cut a 2m-long electrical steel sheet; place its edge flat against the reference edge of the
measuring platform; and use a plug gauge to measure the maximum distance between the edge
of the electrical steel sheet and the reference edge.
6.3.4 Roughness
Firstly, cut a section of 2m-long strip material with waves; and place it freely on the measuring
platform. Use a plug gauge to measure the value h value; use a steel ruler to measure the L
value; and calculate the roughness λ according to Formula (1).
Where:
λ – roughness;
h – maximum height of the rough area, in mm;
L – maximum length of the rough area, in mm.
6.3.5 Burr
Use a micrometer to measure the burr value at any three points on the same shearing surface of
the electrical steel sheet; and take the average value.
6.3.6 Residual curvature
The residual curvature of electrical steel sheet shall comply with the provisions of GB/T 2521.2.
6.3.7 White edge
The white edge of the fixed-length electrical steel strip (sheet) shall be observed by a 20 times
magnifying glass with a scale; and the width of the white edge shall be measured.
6.3.8 Metal hair
Visually measure the edge of the longitudinal shearing to check whether there are tiny hair-like
metal strips at the cut.
6.4 Transverse shearing
6.4.1 Deviation
The sheet length deviation, consistency deviation, angle deviation, hole position deviation,
aperture deviation, and V-notch deviation of the transverse shearing are measured by general
measuring tools that meet the corresponding accuracy requirements.
6.4.2 Mechanical loss
The mechanical loss of the transverse shearing shall be inspected visually.
6.5 Others
Inspection methods for other items shall comply with the provisions in Tables 1, 2, and 3.
7 Inspection Rules
7.1 Each iron core should be inspected, the inspection items are 5.1, 5.2, 5.3, 5.5, and 5.4
according to the requirements of the order agreement.
7.2 The iron core shall pass the inspection according to this standard, and the quality certificate
and quality inspection report shall be attached.
8 Marking, Packaging, Transportation and Storage
8.1 Marking
The product marking shall have the following content:
--- The name or trademark of the manufacturer;
--- Transformer model;
--- Core assembly drawing number and core lamination drawing number;
--- product number;
--- Inspection date, etc.
8.2 Packaging and transportation
It shall be properly packaged according to the transportation requirements to ensure that the
core shall not be deformed, loose, cracked, damaged on the end face, rusted or otherwise
damaged during transportation.
8.3 Storage
The core shall be stored in a ventilated, dry and non-corrosive gas space.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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