Medium voltage evaluations go wrong in a predictable place. The breaker datasheet is thorough, the switchgear datasheet is thin, and nobody notices because both carry a 62271 number on the front page.
The IEC 62271 series covers high voltage switchgear and controlgear, which in IEC terms begins above 1 kV. Two parts of it do most of the work in a distribution specification, and they certify different objects.
IEC 62271-100 is the circuit-breaker standard — alternating-current circuit-breakers for systems above 1000 V. The third edition took effect on 7 July 2021, replacing the 2008 second edition together with its 2012 and 2017 amendments, aligning the text with IEC 62271-1:2017 and restructuring subclauses 7.102 to 7.108. An amendment followed in 2024. It covers the device: what it interrupts, how often, and how reliably.
IEC 62271-200 is the assembly standard — AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV up to and including 52 kV. Its third edition was published on 27 May 2021, replacing the 2011 second edition, with an amendment in 2024. It covers the cubicle: how it is partitioned, what can be worked on while the rest stays live, and what happens when an arc occurs inside it.
What 62271-100 actually declares about the breaker
Beyond the obvious ratings — voltage, normal current, short-circuit breaking current — the standard carries class designations that decide whether a breaker suits the duty. They are the part of the datasheet that gets skipped.
| Class | What it declares |
|---|---|
| E1 / E2 | Electrical endurance. E1 is the basic class. E2 is extended: the interrupting parts are intended to need no maintenance across the expected operating life. |
| M1 / M2 | Mechanical endurance. M1 is 2000 operations. M2 is 10 000. A motorized feeder on an automated network will outrun M1. |
| C1 / C2 | Capacitive switching. C1 is a low probability of restrike, C2 a very low probability, each demonstrated by specific type tests. C1 suits a bank switched rarely; a bank switched daily wants C2. |
| S1 | Intended for use in cable systems, which sets the transient recovery voltage the breaker is proved against. |
The rated operating sequence belongs in the same conversation. The standard defines three: O – 3 min – CO – 3 min – CO; O – 0.3 s – CO – 3 min – CO; and O – 0.3 s – CO – 15 s – CO. Autoreclosing duty on a distribution feeder needs one of the fast sequences, and a breaker proved only on the slow one is not suitable for it whatever its breaking current.
What 62271-200 declares about the assembly: three codes
The assembly carries three classifications, and they describe three different things that specifications routinely collapse into a single line.
Loss of service continuity
The LSC category answers one question: how much of the switchboard has to be taken out of service to open one main circuit compartment?
- LSC1 — the switchgear is put out of service to open a main circuit compartment. Access means an outage.
- LSC2 — the main busbars and the adjacent functional units can remain energized while one compartment is open.
- LSC2A and LSC2B — variants of LSC2 distinguished by how far the segregation goes, with LSC2B separating the busbar, apparatus and cable compartments so that work in one does not require de-energizing the others.
Edition 3 made the LSC description more precise and added an explanatory flowchart in Annex D, which is worth reading before writing the specification line rather than after receiving two different interpretations of it.
Partition class
PM means the partition and shutters between an open compartment and the live parts are metallic and can be earthed. PI means one or more of them is non-metallic. Both are compliant. The difference matters to the operator standing in front of an open cubicle, and it is the kind of distinction that disappears when a specification says only “metal-clad” — a term that is not, by itself, a 62271-200 classification.
Internal arc classification
IAC is the one most often quoted and least often read in full. A complete declaration carries an accessibility type, the sides it applies to, and the current and duration — for example IAC A FLR 25 kA 1 s.
- Type A is for installations where access is restricted to authorized personnel. Type B is for locations accessible to the general public, and is the more onerous.
- F, L, R are the sides the classification covers — front, lateral, rear. FLR is all three. A declaration of IAC A F alone is a front-only classification, and if the room allows rear access it does not describe the installed condition.
- The current and duration must be at least the prospective fault current at that busbar for at least the protection clearing time, with margin. A 1 s classification under a protection scheme that clears in 0.5 s is sound; the same classification where backup protection takes 1.2 s is not.
The test has five acceptance criteria: doors and covers stay closed; no hazardous parts are ejected; no holes appear in the external housing in areas accessible to personnel; the fabric indicators placed around the switchgear are not ignited; and the earthing connections remain effective. Edition 3 introduced a one-second rule for the fourth criterion, distinguishing ignition by hot gases from ignition by glowing particles — a refinement that changes how some older results would be judged, which is another reason the edition of the report matters.
What to require, and in what form
| Require | So that |
|---|---|
| The full IAC string, not the letters IAC | Type, sides, current and duration are all specified rather than assumed |
| The LSC category and partition class together | The operating and maintenance concept is defined, not inferred from “metal-clad” |
| The installation conditions of the arc test, including pressure relief | The room you are building matches the room it was tested in |
| Breaker class designations E, M, C and the operating sequence | The duty the breaker will actually see is the duty it was proved on |
| The edition of each standard the reports are written against | Bids are comparable, and 2011 and 2021 results are not mixed silently |
| Type test reports from an accredited laboratory, not a declaration | The evidence is third-party and traceable |
Where we stand
Our medium voltage ranges are supplied under the Schneider Electric license held for PIX Easy, to 17.5 kV, with testing and commissioning carried out in Madinah. Type test evidence for the ranges we supply, including internal arc classification with its installation conditions, is issued against a named enquiry rather than published for download. The documentation register lists each standard with its reference and validity, and says plainly which licenses are held and which are under application.