Integration of internal arc-fault mitigation systems in power switchgear and controlgear assemblies (PSC-assemblies) according to GB/T 7251.2-2023
1 Scope
This document states requirements for integration and testing of IAMS in low-voltage switchgear and controlgear assemblies - power switchgear and controlgear assemblies according to GB/T 7251.1-2023 and GB/T 7251.2-2023 to demonstrate their correct operation.
This document does not address personnel safety or damage to the PSC-assembly. These requirements are dealt with in GB/T 18859-20160 (see 10.10.1).
Note: This document can be used as a reference for other types of assemblies in the GB/T 7251 (all parts), but adaptation of the test procedures and acceptance criteria can apply taking into account the specifics of such other assemblies or products.
IAMS consist of IACDs and IARDs complying with their relevant product standard (e.g. optical based IACDs in accordance with IEC 60947-9-2, AQDs in accordance with IEC 60947-9-1 and SCPDs in accordance with IEC 60947-2). For the reliable function in a PSC-assembly, the verification of correct operation of the complete system under built-in conditions is addressed.
This document applies only to enclosed PSC-assemblies and deals with all required verifications needed for the integration in conjunction with GB/T 7251.1-2023 and GB/T 7251.2-2023.
The test procedure given in this document takes into consideration:
- the correct function of the IAMS within the PSC-assembly;
- the prevention of unintended operation of the IAMS within the PSC-assembly;
- the functioning behaviour of the system immediately after the assembly is energised.
Different tests under more severe conditions (e.g. doors in open position) an be performed with an agreement between the user and the original manufacturer of the PSC-assembly.
This document does not supersede any individual product standard. Individual devices are required to comply with their relevant standard.
This document does not apply to integration of arc fault detection devices (AFDD) according to IEC 62606.
The informative Annex lI gives guidance on particular constructional requirements for incorporation of IAMS within a PSC-assembly.
The informative Annex HH gives guidance for the user of PSC-assemblies about the criteria to be considered when specifying a PSC-assembly with an integrated IAMS.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 7251.1-2023 Low-voltage switchgear and controlgear assemblies - Part 1: General rules (IEC 61439-1:2020, IDT)
GB/T 7251.2-2023 Low-voltage switchgear and controlgear assemblies - Part 2:Power switchgear and controlgear assemblies (IEC 61439-2:2020, IDT)
GB/T 18859-2016 Enclosed low-voltage switchgear and controlgear assemblies - Guide for testing under conditions of arcing due to internal fault (IEC TR 61641:2014, IDT)
IEC 60947-9-1:2019 Low-voltage switchgear and controlgear - Part 9-1: Active arc-fault mitigation systems- Arc quenching devices
Note: GB/T 14048.23-2022 Low-voltage switchgear and controlgear - Part 9-1 : Active arc-fault mitigation systems - Arc quenching devices (IEC 60947-9-1:2019, MOD)
IEC 60947-9-2:2021 Low-voltage switchgear and controlgear - Part 9-2: Active arc fault mitigation systems- Optical-based internal arc detection and mitigation devices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 7251.2-2023, and the following apply.
3.1
internal arc-fault mitigation system; IAMS
system consisting of an internal arc-fault control device (IACD) and an internal arc-fault reduction device (IARD) that operates in case of an internal arc-fault
Note: An IAMS can include a "combined type" single device which combines the functions of an IACD and an IARD as defined in IEC 60947-9-2.
3.2
internal arc-fault control device; IACD
device intended to detect an internal arc-fault, which provides a signal for operation of a separate mitigation device, or automatically mitigates the internal arc-fault
Note: IACD with mitigation capability combines in the same device internal arc-fault detection and breaking or making capabilities.
[Source: IEC 60947-9-2 : 2021, 3.3]
3.3
internal arc-fault reduction device; IARD
device intended to reduce the energy released by an internal arc-fault
Note: An IARD can be achieved by a SCPD, AQD or IALD
3.3.1
arc quenching device; AQD
IARD intended to eliminate internal arc-faults by creating a lower impedance current path in order to cause the arcing current to transfer to the new current path
[Source: IEC 60947-9-1:2019, 3.1, modified - In the definition "device" has been replaced with "IARD" and Note 1 has been deleted]
3.3.2
internal arc-fault limiting device; IALD
IARD intended to reduce the arc-fault current below a particular level other than a SCPD with current limiting functionality e.g. fuse or circuit-breaker
3.4
IAMS protected area
area monitored by an IAMS where an internal arc-fault is detected, mitigated and finally extinguished, and where unintended operation as a result of a switching arc will not occur
3.5
automatic transfer switching equipment; ATSE
self-acting transfer switching equipment
Note 1: ATSE normally includes all necessary devices for monitoring and transferring operations.
Note 2: ATSE can have an optional feature for manual operation.
[Source: IEC 60947-6-1:2005/AMD 1 : 2013, 3.1.4]
3.6
arc-fault mitigation time in an assembly
tmtA
interval of time between the ignition t0 to of the internal arc-fault and the significant commutation of currents into the AQD
Note 1: Arc-fault mitigation time in an assembly is as described in Figure JJ.2 between points c) and g).
Note 2: For applications without AQD(s) the arc-fault extinction time of IEC 60947-9-2 can be used as an alternative to tmtA.
3.7
arc-energy
Earc
energy released by the arc during the arcing-fault
4 Symbols and abbreviated terms
For the purposes of this document, symbols and abbreviated terms given in GB/T 7251.2 -2023, as well as those given in Table 1, apply.
