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GB/T 7251.2-2023 PDF in English

GB/T 7251.2-2023 (GB/T7251.2-2023, GBT 7251.2-2023, GBT7251.2-2023)
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GB/T 7251.2-2023: PDF in English (GBT 7251.2-2023)

GB/T 7251.2-2023
ICS 29.130.20
CCS K 31
GB/T 7251.2-2023 / IEC 61439-2:2020
Replacing GB/T 7251.12-2013
Low-Voltage Switchgear and Controlgear Assemblies
– Part 2: Power Switchgear and Controlgear Assemblies
(IEC 61439-2:2020, IDT)
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 7
1 Scope ... 8
2 Normative References ... 9
3 Terms and Definitions ... 10
4 Symbols and Abbreviations ... 13
5 Interface Characteristics ... 13
6 Information ... 15
7 Service Conditions ... 15
8 Constructional Requirements ... 15
9 Performance Requirements ... 20
10 Design Verification ... 20
11 Routine Verification ... 25
Annexes ... 28
Annex AA (Informative) Items Subject to Agreement between the PSC-Assembly
Manufacturer and the User ... 29
Annex BB (Informative) Forms of Internal Separation (see 8.101) ... 33
Annex CC (Informative) Determining Power Loss by Measurement for Circuits
Exceeding 1600 A in a Reference Design ... 39
Annex DD (Informative) Assemblies for Use in Photovoltaic Installations ... 41
Annex EE (Informative) Items Subject to Agreement between the Photovoltaic
Assembly (PVA) Manufacturer and the User ... 52
Annex FF (Informative) Design Verification (PVA Only) ... 56
Annex GG (Informative) List of Notes Concerning Certain Countries ... 58
Bibliography ... 59
This Document was drafted as per the rules specified in GB/T 1.1-2020 Directives for
Standardization – Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This Document is Part 2 of GB/T 7251 Low-Voltage Switchgear and Controlgear Assemblies.
GB/T 7251 has published the following parts:
--- Part 1: General rules;
--- Part 2: Power switchgear and controlgear assemblies;
--- Part 3: Distribution boards intended to be operated by ordinary persons (DBO);
--- Part 4: Particular requirements for assemblies for construction sites (ACS);
--- Part 5: Particular requirements for assemblies for power distribution in public networks;
--- Part 6: Busbar trunking systems (busways);
--- Part 7: Assemblies for specific applications such as marinas, camping sites, market
squares, electric vehicles charging stations;
--- Part 8: General technical requirements for intelligent assembly;
--- Part 10: Guidance to specifying assemblies.
This Document replaced GB/T 7251.12-2013 Low-Voltage Switchgear and Controlgear
Assemblies - Part 2: Power Switchgear and Controlgear Assemblies. Compared with GB/T
7251.12-2013, the technical changes of this Document are as follows besides the structural
adjustments and editorial modifications:
--- Add requirements for photovoltaic installation assemblies (see Annexes DD, EE and FF
of this Edition);
--- Change the requirements for the internal isolation form. When the isolation form is
greater than 1, when the functional unit is turned off, the protection level of all still
running components between the functional units shall be at least IPXXB (see 8.101 of
this Edition; 8.101 of 2013 Edition);
--- Add the verification method in the verification and evaluation method of temperature rise
(i) Verify the temperature rise of assemblies with natural cooling and circuits with rated
currents above 1600A through comparison with reference designs and calculations; (ii)
Verify the temperature rise for assemblies with active cooling and rated current not
exceeding 1600A. (See, of this Edition);
Low-Voltage Switchgear and Controlgear Assemblies
– Part 2: Power Switchgear and Controlgear Assemblies
1 Scope
This Document defines the specific requirements for the power switchgear and controlgear
assembly (abbreviated ‘PSC-assembly’ throughout this Document see 3.1.101) as follows:
--- assemblies for which the rated voltage does not exceed 1 000 V AC or 1 500 V DC;
--- assemblies designed for a nominal frequency of the incoming supply or supplies not
exceeding 1 000 Hz;
NOTE 1: Frequencies above 1 kHz are considered as high frequencies, see also GB/T 16935.1-
2008, to take into account additional constraints to insulation coordination.
--- assemblies intended for indoor and outdoor applications;
--- stationary or movable assemblies with or without enclosures;
--- assemblies intended for use in connection with the generation, transmission, distribution
and conversion of electrical energy, and for the control of equipment consuming
electrical energy and for associated data processing;
--- assemblies designed for use under special service conditions, for example in ships and in
rail vehicles, provided that the other relevant specific requirements are complied with;
NOTE 2: Supplementary requirements for assemblies in ships are covered by IEC 60092-302-2.
This Document also applies to assemblies for use in photovoltaic installations, designated as
photovoltaic assemblies (PVA). The particular characteristics, specific service conditions and
the requirements for PVA’s are included in Annexes DD, EE and FF.
This Document provides supplementary requirements for PSC-assemblies intended for use as
part of the electrical equipment of machines and can be applied in addition to the requirements
given in IEC 60204-1.
This Document applies to all assemblies whether they are designed, manufactured and verified
on a one-off basis or fully standardized and manufactured in quantity.
The manufacture and/or assembly can be carried out by an entity other than the original
manufacturer (see 3.10.1 of GB/T 7251.1-2023).
test position (see 3.2.102), or a test situation (see 3.1.102). They shall be distinctly located in
these positions. These positions shall be clearly discernible.
In PSC-assemblies with withdrawable parts all live parts shall be protected in such a manner
that they cannot unintentionally be touched when the door, if any, is open and the withdrawable
part is withdrawn from the connected position or removed. Where an obstacle or shutter is used
they shall meet the requirements of of GB/T 7251.1-2023.
For the electrical conditions associated with the different positions of withdrawable parts, see
Table 103. Interlocking and padlocking of removable and withdrawable parts
A removable or withdrawable part shall be fitted with a device that ensures that it can only be
removed and inserted after its main circuit has been switched off from the load.
In order to prevent unauthorized operation, the removable and withdrawable parts or their
associated assembly location may be provided with a lockable means to secure them in one or
more of their positions.
8.5.3 Selection of switching devices and components
NOTE 2: The standards with which components can comply, include, for example, IEC 60947 (all parts),
IEC 60269 (all parts), IEC 60898 (all parts), IEC 61008 (all parts), IEC 61009 (all parts), IEC 62423,
IEC 61800-5-1, IEC 61010-2-201.
Additional subclauses:
8.5.101 Description of the types of electrical connections of functional units
A functional unit can have the same or different types of electrical connection for incoming and
outgoing supplies; for example, a withdrawable connection can be used for the incoming and
fixed or disconnectable for the outgoing.
NOTE 1: Particularly when multiple supplies are involved, the specifier carries out an assessment in
order to choose the most appropriate connection.
The types of electrical connections of functional units within PSC-assemblies or parts of PSC-
assemblies can be denoted by a three-letter code:
– the first letter denotes the type of electrical connection of the main incoming circuit;
– the second letter denotes the type of electrical connection of the main outgoing circuit;
– the third letter denotes the type of electrical connection of the auxiliary circuits.
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.