Internal Arc Classification for MV Switchgear: IAC AFL/AFLR, Access, and Project Inputs

Switchgear internal arc classification AFL AFLR is common RFQ shorthand, but selection requires a complete declaration, not a catalogue label. Define who can access the installation, which enclosure sides remain accessible, the project arc current and duration, the exact lineup/compartment configuration, and the room pressure-relief conditions. Then require evidence that maps those conditions to the offered assembly.

Visual disclosure: all images are generated illustrative technical visualizations, not XIYA POWER factory, design, test, FAT, manufacturing, installation, commissioning, or field photographs.

Decode the Complete IAC Declaration Before Comparing Offers

Internal arc classification (IAC) under IEC 62271-200 describes a metal-enclosed switchgear assembly tested under defined internal-arc conditions. The declaration combines the accessibility type, classified sides, prospective arc current, and arc duration. All elements are needed for comparison.

A complete example is IAC AFL 20 kA, 0.5 s. Schneider Electric’s official IAC accessibility FAQ explains the public notation. Type A restricts access to authorized personnel; F/L designate the front/lateral classified sides; 20 kA is the stated current; and 0.5 seconds is the stated duration. The same source defines types B/C and the R rear-side designator. Clause-level requirements remain controlled by the purchased standard, project specification, and configuration-applicable manufacturer evidence.

Declaration element	Example	Selection meaning	Hold condition
Classification prefix	IAC	Internal arc classification is declared	Prefix missing or replaced by marketing wording
Accessibility type	A	Access restricted to authorized personnel	Project access model not matched
Classified sides	FL	Front and lateral sides are included	An accessible side is omitted
Arc current	20 kA	Stated prospective arc current for the test	Project fault basis or evidence missing
Arc duration	0.5 s	Stated duration for the test	Protection clearing basis unresolved

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A bare AFL or AFLR is incomplete without current, duration, and applicable evidence. The Complete Switchgear Cabinets owner provides family context, but no family name proves an IAC declaration for every bay, compartment, or installation arrangement.

Select Accessibility Type and Classified Sides From the Operating Model

Accessibility type describes who may be near the enclosure under the defined installation and operating model:

• Type A: restricted to authorized personnel only.
• Type B: unrestricted accessibility, including the general public.
• Type C: restricted by installation out of reach above a public area; F/L/R side designators do not apply in the same way.

For types A and B, F is front, L is lateral, and R is rear. The manufacturer identifies the front of the equipment. The project identifies which faces people can occupy or reach during energized service, switching, inspection, or work on an isolated compartment while adjacent equipment remains energized.

Project access condition	Required input	Decision	Supplier return	Hold condition
Front operating aisle only	Room plan and access rules	Confirm front-side requirement	Complete IAC code and evidence	Other sides are not demonstrably inaccessible
Front plus lineup-end access	End-panel and barrier arrangement	Include lateral-side review	F/L classification mapping	End condition absent from evidence
Rear corridor occupied while lineup/adjacent bays remain energized	Rear access and operating states	Rear side must be resolved	Applicable R evidence or accepted access redesign	AFL offered with accessible rear
Public presence near enclosure	Occupancy and barriers	Review type B or C need	Type/accessibility declaration	Type A is assumed without control

The difference between AFL and AFLR is therefore not cosmetic. AFL includes front and lateral sides; AFLR also includes rear. If the rear remains accessible under an energized operating state, the project needs an applicable rear-side solution or a reviewed physical/access redesign that genuinely removes that exposure.

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The fixed-versus-withdrawable decision changes compartments, access routes, and maintenance states, but does not by itself assign IAC. Use the XGN versus KYN28 project-fit guide for that upstream architecture decision, then apply the actual room and operating model here.

Match Arc Current and Duration to the Project Fault and Protection Basis

Derive the required arc current and duration from current project sources. Current inputs come from the short-circuit study at the switchgear location, including applicable source contributions and operating configurations. Duration inputs come from the approved protection clearing basis, including the relevant primary and backup scenario defined by the project risk model.

Utility rules and the project specification may set additional requirements. Record each value’s source, revision, system state, and owner. Do not select an IAC current/duration from a catalogue maximum or a previous project.

Input	Required source	Supplier comparison	Release evidence
Prospective arc current	Current short-circuit study and operating configuration	Offered IAC current is not below the specified value	Report/declaration for exact configuration
Arc duration	Protection clearing basis and project rule	Offered duration is not below the specified value	Applicable test duration and protection reference
Accessibility/side requirement	Room, barriers, occupancy, and operating states	Offered code covers every required side/type	Side mapping and installation evidence
Variant/configuration	Bay schedule, compartments, end panels, relief system	Offered assembly remains within evidence scope	Applicability matrix and deviations

A numerically higher current or longer duration is not sufficient by itself. It cannot repair a missing classified side, wrong accessibility type, different pressure-relief arrangement, or inapplicable report. The MV switchgear RFQ data guide owns the wider SLD, bay, fault-duty, room, and protection input package.

Coordinate the Switchgear, Room, and Pressure-Relief Path as One Installation

Internal-arc evidence is obtained with defined equipment and installation conditions. The project must show that the offered lineup and room replicate those conditions or remain within a documented applicability boundary.

Installation input	Project return	Evidence question	Hold condition
Wall or free-standing arrangement	Dimensioned room/GA	Was the same arrangement represented?	Arrangement differs without review
End panels and lineup length	Bay schedule and end treatment	Are ends and representative cubicles covered?	End/lineup scope unclear
Compartments and bay variants	Configuration schedule	Which internal-arc test locations apply?	Variant inferred from family name
Doors, covers, and relief flaps	Operating-state schedule	Does the tested state match normal service?	Required part/state omitted
Plenum or pressure-relief duct	Duct drawing and exhaust destination	Does the evidence include this route?	Duct/vent path not mapped
Ceiling, wall, and side clearances	Coordinated room drawing	Are clearances within evidence conditions?	Geometry is outside the record
Cable trenches and floor openings	Civil/interface drawing	Was opening treatment represented?	Uncontrolled exhaust path remains
Occupied areas	Access and barrier plan	Are hot gases routed away from people?	Exhaust reaches an occupied path

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Manufacturer data should identify the tested object, lineup arrangement, compartments, relief system, room conditions, and exclusions. A different end panel, open trench, ceiling height, duct, or exhaust destination can change applicability even when the cabinet type code is unchanged.

For one common family, the KYN28 switchgear specification assigns classification, compartment, interlock, and room-interface inputs to the exact panel schedule. CAB-07 does not infer IAC from the KYN28 name; it requires the offered configuration’s evidence.

Require Configuration-Applicable Evidence and State What IAC Does Not Prove

Issue an IAC RFQ checklist and data pack that normalizes every supplier return:

1. Exact family, type designation, rating schedule, bay types, and compartments.
2. Complete IAC code: accessibility type, F/L/R sides, current, and duration.
3. Test report or declaration reference, laboratory, date, and tested object.
4. Lineup length, representative cubicles, end-panel configuration, and test locations.
5. Doors/covers state, pressure-relief flaps, plenum/duct, and exhaust destination.
6. Wall/free-standing arrangement, clearances, cable trench/opening treatment, and barriers.
7. Applicability matrix from the tested object to every offered variant.
8. Deviations, exclusions, engineering review status, and required release evidence.

Normalize each return against the same project rows. Mark an entry as a project requirement, supplier declaration, report result, applicability statement, deviation, or unresolved assumption. Record the source revision and affected bays beside it. This prevents a compliant headline on one representative cubicle from being reused silently for a different end panel, compartment, duct, or lineup arrangement.

An IAC report is not an insulation test record. The insulation resistance versus power-frequency withstand guide explains those two tests and their different outputs. Neither proves IAC, and IAC does not replace either where required.

IAC also does not prove that an internal arc cannot occur, that no injury is possible, or that equipment remains serviceable afterward. It does not establish LSC, partition class, IP rating, general fault duty, insulation level, interlock performance, earthing, pressure-relief adequacy for a different room, or every variant in a product family. Avoid arc-proof; use internally arc classified for the stated type, sides, current, duration, configuration, and installation conditions.

The complete FAT evidence pack, routine reports, deviations, retests, and final release records are a separate downstream activity. CAB-07 defines the IAC selection evidence that must enter that later pack.

Hold an Illustrative AFL Offer With an Accessible Rear Corridor

Representative engineering review, not a XIYA POWER customer, factory, design, test, FAT, installation, commissioning, or field case. All values and room conditions are illustrative and non-universal.

A 12 kV lineup has a project input of 20 kA and a protection clearing basis of 0.7 s. The supplier headline is IAC AFL 25 kA, 1 s. The room has a 1,500 mm front operating aisle, 800 mm lateral access at the lineup end, and an 800 mm rear cable corridor. Authorized personnel may use the rear corridor while adjacent bays remain energized.

Required input	Decision	Supplier return	Release evidence	Hold condition
Type A access	Authorized-only operating area	A stated	Applicable report required	None at notation level
Project current/duration	20 kA and 0.7 s basis	25 kA and 1 s stated	Exact configuration not yet mapped	Numeric headline alone is insufficient
Accessible sides	Front, lateral, and rear	AFL; rear omitted	No rear-side mapping	Accessible rear is unclassified
End-panel arrangement	Offered end condition must be covered	Not confirmed	Pending	Evidence applicability open
Pressure-relief duct	Offered duct/room path must be covered	Not mapped	Pending	Installation applicability open

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The apparently higher current and duration do not close the rear-side or evidence gaps. Decision: hold. Request an applicable AFLR offer that maps the rear side, end panel, compartments, and relief duct. Alternatively, complete a reviewed room/access redesign that genuinely removes rear accessibility during energized service. No final selection, design approval, test, FAT, installation, or release outcome is claimed.

Frequently Asked Questions

What does IAC AFL mean on MV switchgear?

It declares internal arc classification with accessibility type A and classified front/lateral sides. A complete declaration also states arc current and duration and requires evidence for the offered configuration.

What is the difference between IAC AFL and AFLR?

AFL covers front and lateral sides. AFLR also covers the rear. The project decides whether rear classification is required by reviewing actual room access, barriers, and energized operating states.

Does a higher IAC current automatically make an offer acceptable?

No. Current and duration must meet the specified basis, but accessibility type, classified sides, configuration, room/relief conditions, and evidence applicability must also close.

Does IAC prove the switchgear is arc-proof?

No. IAC is a classification under stated test conditions. It does not guarantee that an arc cannot occur, zero injury, access to unclassified sides, or post-event serviceability.

How do room layout and pressure relief affect IAC selection?

The room defines accessible sides and the exhaust path. End panels, clearances, ducts, flaps, trenches, barriers, and occupied areas must remain within the evidence conditions for the offered lineup.

What evidence should a supplier return for an IAC requirement?

Require the complete code, report/declaration, tested object, covered bays/compartments, end arrangement, relief route, installation conditions, applicability matrix, deviations, and release-evidence path.