UniGear IEC 62271-200: New Standard for Medium Voltage Switchgear

Medium Voltage Products
UniGear
IEC 62271-200; the new standard
for medium voltage switchgear
Index
1. Why has the standard been renumbered? 2
2. A look back to the “old” standard 3
3. New requirements for switchgear 4
4. UniGear in accordance with IEC 62271-200 10

2
IEC 62271-200
The IEC 62271-200 standard: “High voltage switchgear and
controlgear – Part 200: AC metal-enclosed switchgear and
controlgear for rated voltages above 1 kV and up to and
including 52 kV”, was issued in November 2003.
This international standard is a further development of the
previous IEC 60298 standard of 1990.
One aim of the new issue was to focus more on functional
characteristics than on design and construction, and to avoid
terms such as “metal-clad” which are also used in North
American standards (ANSI) and always lead to confusion as
the definitions of that term are different in the two standards.
In parallel with revision of the standard, the IEC Technical
Committee TC 17 decided to renumber all standards referring
to high voltage switchgear under the main number 62271.
As is customary at IEC, in contrast to European standards
(EN), the standard was issued without a transitional period.
At the end of the 1990s, the responsible IEC committees
started revising the switchgear standard which was finally
published as IEC 62271-200 and came into force in
November 2003.
At the same time, the old IEC 60298 was withdrawn without
any transitional period. This was followed by the adoption of
IEC 62271-200 as European standard EN 62271-200.
After a transitional period of three years, which ended on
01 February 2007, these standards become valid without
restriction and completely replace EN 60298 and CEI 60298.
All standards for medium voltage will in future appear in the
62271-… category.
In a similar manner, IEC 60056 has become IEC 62271-100.
IEC
(International Electrotechnical Commission)
Valid from 01 November 2003 as IEC 62271-200,
(The old IEC 60298 was withdrawn without a transitional
period.)
CENELEC
(Comité Européen de Normalisation Electrotechnique)
Valid from 01.02.2004 as European standard EN 62271-200
(There was a three year transitional period which ended on
01.02.2007).
Foreword
This standard has been fundamentally revised to reflect
the state-of-the-art for high voltage switchgear up to 52kV.
The significant changes comprise new terms, classes of
switchgear installations, introduction of a new arc fault
qualification (IAC) and the corresponding tests.
1. Why has the standard been
renumbered?

3
2. A look back to the “old” standard
Types of partitioning
In order to ensure access to individual components within the
switchgear installation, e.g. for maintenance work on circuit-
breakers without isolation of the busbar, IEC 60298 distin-
guished among three different types of partitioning with regard
to protection against accidental contact:
• Metal-clad:
Division of the panel into four compartments:
- Busbar compartment;
- Switching device compartment;
- Cable termination compartment;
- Low voltage compartment.
Partition material between the individual compartments was
sheet steel. Material for shutters was sheet steel or plastic.
• Compartmented:
Division of the panel as for metal-clad, but plastic as the
partition material between the individual compartments.
• Cubicle-type:
All other construction types which do not comply with the
characteristics of metal-clad or compartmented systems as
stated above.
IEC 60298
IEC 60298 / CEI 60298 was the measure of all things for
decades where type tests on metal-enclosed switchgear
were concerned. On the basis of that standard, several tens
of thousands of panels from ABB are in service worldwide
with an excellent operating record, having been type tested in
accordance with the mandatory section of the standard and
the optional test with an internal arc fault.
It was necessary for switchgear to pass the following tests to
be designated “type tested”.
Dielectric test
To demonstrate the insulation level of the switchgear.
Testing of:
• Rated lightning impulse voltage;
• Rated short-time power frequency withstand voltage.
Impulse and short-time current tests
To demonstrate the thermal and dynamic current carrying
capacity of the main and earthing conductors.
Switching test
To demonstrate the making and breaking capacities of the
switching devices installed.
Temperature rise tests
To demonstrate the current carrying capacity at rated opera-
ting currents.
Protection tests
To demonstrate protection against accidental contact and
against foreign bodies.
Mechanical functional test
To demonstrate the mechanical functions and the interlocks.
Arc fault protection
There was also the opportunity to test switchgear for arc fault
resistance and operator protection. Testing with an internal
arc fault was voluntary and could be agreed on by the manu-
facturer and operator. Assessment of the tests depended on
six criteria.
It was, however, not defined that all the criteria had to be pas-
sed completely, and there was no formal classification of the
switchgear according to accessibility and arcing time.

4
3. New requirements for switchgear
Overview of IEC 62271-200
Changed sequence for dielectric testing
Under the terms of IEC 60298, the test at rated lightning
impulse voltage was conducted with 15 voltage impulses in a
series, with two disruptive discharges being permissible.
SF6 or vacuum circuit-breaker: two quenching techniques make it easy to
satisfy the customer’s needs in the best possible way.
According to the new standard, 15 voltage impulses are again
to be applied in a series, and two disruptive discharges are
still permissible.
However, an impulse which has caused a disruptive discharge
must be followed by at least 5 impulses without disruptive
discharge.
The test series must be extended if the disruptive discharge
occurs in one of the last 5 impulses of the series of 15.
This can lead to a maximum of 25 impulses per series, and
the total number of disruptive discharges in the series must
still not exceed two.
This test sequence is intended to ensure that all disruptive
discharges take place on self-restoring insulation only.
Under the old standard, this was verified by visual inspection,
which is now no longer necessary.
Firming up of test conditions for the switching devices
(making and breaking capacity)
Switching devices in the main circuit and earthing switches
are to be tested to demonstrate their rated making and
breaking capacities as normally installed in the metal-
enclosed switchgear with all associated components.
This is intended to take account of any influence of the
enclosure on switching behaviour.

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D
B
A
C
Introduction of new partition classes
With regard to the type of partitions or shutters between
live parts and an open compartment, a distinction is made
between two partition classes (see Table 1):
• Class PM (Partition made of Metal);
• Class PI (Partition made of Insulating material).
Switchgear classification with regard to the nature of the barrier
between live parts and open accessible compartment.
PM Metallic shutters and partition between live parts and open
compartment – (metal-enclosed condition maintained)
PI Insulation-covered discontinuity in the metallic partitions/
shutters between live parts and open compartment
Table 1
Metallic, shockproof surfaces in accordance with class PM Single Level UniGear - compartments
Low voltage compartment
Busbar compartment
Circuit-breaker compartment
Feeder compartment