SIST EN 50052:2017

SLOVENSKI STANDARD
SIST EN 50052:2017
01-februar-2017
1DGRPHãþD
SIST EN 50052:1998
SIST EN 50052:1998/A2:1998
Ohišja iz lite aluminijeve zlitine za plinske visokonapetostne stikalne in krmilne
naprave
Cast aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear
Kapselungen aus Leichtmetallguss für gasgefüllte Hochspannungs-Schaltgeräte und -
Schaltanlagen
Enveloppes en alliage d'aluminium coulé pour l'appareillage à haute tension sous
pression de gaz
Ta slovenski standard je istoveten z: EN 50052:2016
ICS:
29.130.10 Visokonapetostne stikalne in High voltage switchgear and
krmilne naprave controlgear
77.150.10 Aluminijski izdelki Aluminium products
SIST EN 50052:2017 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50052:2017

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SIST EN 50052:2017


EUROPEAN STANDARD EN 50052

NORME EUROPÉENNE

EUROPÄISCHE NORM
December 2016
ICS 29.130.10 Supersedes EN 50052:1986
English Version
High-voltage switchgear and controlgear - Gas-filled cast
aluminium alloy enclosures
Enveloppes moulées en alliage d'aluminium pour les Hochspannungs-Schaltgeräte und -Schaltanlagen -
appareillages à haute tension sous pression de gaz Gasgefüllte Kapselungen aus Leichtmetallguss
This European Standard was approved by CENELEC on 2016-09-12. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 50052:2016 E

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SIST EN 50052:2017
EN 50052:2016 (E)
Contents Page
European foreword .4
Introduction .5
1 General .6
1.1 Scope .6
1.2 Normative references .6
1.3 Quality assurance .7
2 Normal and special service conditions .7
3 Terms and definitions .7
4 Materials . 10
4.1 Selection of material. 10
4.2 Chemical analysis. 11
5 Design . 11
5.1 General . 11
5.2 Calculation Methods. 12
5.2.1 General . 12
5.2.2 Evaluation of mechanical strength using “Design by Formula” . 12
5.2.3 Evaluation of mechanical strength using “Design by Analysis” . 12
5.2.4 Flanges . 13
5.2.5 Bolted connections . 14
5.3 Inspection and access openings . 14
6 Manufacture and workmanship . 14
6.1 Manufacture . 14
6.2 Consultation between manufacturer and founder . 14
6.3 Foundry technique . 14
6.4 Geometry and dimensions . 15
6.5 Chemical composition and mechanical properties . 15
6.5.1 Sampling . 15
6.5.2 Chemical composition . 15
6.5.3 Mechanical properties . 15
6.6 Workmanship . 15
6.6.1 Surface finish . 15
6.6.2 Soundness . 15
7 Repair of casting defects . 16
7.1 General . 16
7.2 Repair by welding . 16
7.2.1 Welding performance test . 16
7.2.2 Weld procedure . 16
7.2.3 Weld procedure test . 16
7.2.4 Application to castings . 17
7.2.5 Preparation of castings for weld repairs . 17
7.2.6 Inspection of weld repair areas . 18
7.3 Impregnation of castings . 18
8 Thermal treatment . 18
8.1 Thermal treatment procedure . 18
8.2 Methods of heating . 18
8.3 Quenching . 18
8.4 Calibration of furnace temperature. 18
8.5 Thermal treatment charts . 18
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9 Inspection, testing and certification . 19
9.1 Type tests . 19
9.1.1 General . 19
9.1.2 Burst test procedure . 19
9.1.3 Strain measurement test . 19
9.2 Inspection and routine tests . 20
9.2.1 General . 20
9.2.2 Visual inspection . 20
9.2.3 Dye penetrant examination . 20
9.2.4 Radiographic examination . 20
9.2.5 Ultrasonic examination . 20
9.2.6 Reporting of non-destructive test examinations . 21
9.2.7 Routine pressure test . 21
9.2.8 Tightness test . 21
9.3 Certification . 21
9.3.1 Design specification, drawings and data sheets . 21
9.3.2 Certificate . 21
9.3.3 Stamping . 21
9.3.4 Final inspection of castings . 21
10 Pressure relief devices . 21
10.1 General . 21
10.2 Bursting discs . 22
10.3 Self-closing pressure relief valves . 22
10.4 Non-self-closing pressure relief devices . 22
Annex A (informative) A-deviations . 24
Bibliography . 26

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SIST EN 50052:2017
EN 50052:2016 (E)
European foreword
This document (EN 50052:2016) has been prepared by CLC/TC 17AC “High-voltage switchgear and
controlgear”.
The following dates are fixed:
• latest date by which this document has (dop) 2017-09-12
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2019-09-12
standards conflicting with this
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 50052:1986.
This European Standard supplements the relevant product standards on gas-insulated switchgear and
controlgear in that it provides specific requirements for pressurized high-voltage switchgear and controlgear.
This European Standard has been written to get a European specification for the design, construction,
testing, inspection and certification of pressurized enclosures used in high-voltage switchgear and
controlgear.
In this respect, this European Standard constitutes the exclusion of HV switchgear from the scope of the
Directive 2014/68/EU (superseding 97/23/EC) concerning pressure equipment. Article 1, 2. (l) excludes
“enclosures for high-voltage electrical equipment such as switchgear, controlgear, transformers, and rotating
machines” from the scope of the Directive.
This European Standard deals with gas-insulated switchgear enclosures of cast aluminium alloy. For
different enclosure materials other European Standards are available.
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EN 50052:2016 (E)
Introduction
This standard covers the requirements for the design, construction, testing, inspection and certification of
gas-filled enclosures for use specifically in high-voltage switchgear and controlgear, or for associated gas-
filled equipment.
Special consideration is given to these enclosures for the following reasons.
(a) The enclosures usually form the containment of electrical equipment, thus their shape is determined by
electrical rather than mechanical requirements.
(b) The enclosures are installed in restricted access areas and the equipment is operated by instructed,
authorized persons only.
(c) As the thorough drying of the inert, non-corrosive gas medium is fundamental to the satisfactory
operation of the electrical equipment, the gas is periodically checked. For this reason, no internal corrosion
allowance is required on the wall thickness of these enclosures.
(d) The enclosures are subjected to only small fluctuations of pressure as the gas-filling density shall be
maintained within close limits to ensure satisfactory insulating and arc-quenching properties. Therefore the
enclosures are not liable to fatigue due to pressure cycling.
(e) The operating pressure is relatively low.
Due to the foregoing reasons and to ensure maximum service continuity as well as to reduce the risk of
moisture and dust entering the enclosures which may endanger safe electrical operation of the switchgear,
no pressure tests should be carried out after installation and before placing in service and no periodic
inspection of the enclosure interiors or pressure tests should be carried out after the equipment is placed in
service.
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SIST EN 50052:2017
EN 50052:2016 (E)
1 General
1.1 Scope
This European Standard applies to cast aluminium alloy enclosures pressurized with dry air, inert gases, for
example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor or outdoor installations
of high-voltage switchgear and controlgear above 1 kV, where the gas is used principally for its dielectric
and/or arc-quenching properties with rated voltages
- above 1 kV and up to and including 52 kV and with gas-filled enclosures with design pressure higher
than 300 kPa relative pressure (gauge);
- and with rated voltage above 52 kV.
The enclosures comprise parts of electrical equipment not necessarily limited to the following examples:
- Circuit-breakers
- Switch-disconnectors
- Disconnectors
- Earthing switches
- Current transformers
- Voltage transformers
- Surge arrestors
- Busbars and connections
- etc.
The scope also covers enclosures of pressurized components such as the centre chamber of live tank
switchgear, gas-insulated current transformers, etc.
1.2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 10204, Metallic products — Types of inspection documents
EN 12258-1:2012, Aluminium and aluminium alloys — Terms and definitions — Part 1: General terms
EN 50064, Wrought aluminium and aluminium alloy enclosures for gas-filled high-voltage switchgear and
controlgear
EN 62271-1:2008, High-voltage switchgear and controlgear — Part 1 Common specifications (IEC 62271-
1:2007)
EN 62271-203:2012, High-voltage switchgear and controlgear — Part 203: Gas-insulated metal-enclosed
switchgear for rated voltages above 52 kV (IEC 62271-203:2011)
EN ISO 898 (series), Mechanical properties of fasteners made of carbon steel and alloy steel
EN ISO 6520-1:2007, Welding and allied processes — Classification of geometric imperfections in metallic
materials — Part 1: Fusion welding (ISO 6520-1:2007)
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EN ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel (ISO 9712)
EN ISO 15614-4, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 4: Finishing welding of aluminium castings (ISO 15614-4)
1.3 Quality assurance
It is the intention of this standard that the switchgear manufacturer shall be responsible for achieving and
maintaining a consistent and adequate quality of the product.
Sufficient examinations shall be made by the founder to ensure that the materials, production and testing
comply in all respects with the requirements of this standard.
Inspection by the user inspectors shall not absolve the manufacturer or the founder from their responsibility
to exercise such quality assurance procedures as to ensure that the requirements of this standard are
satisfied.
2 Normal and special service conditions
Clause 2 of EN 62271-1:2008 is applicable.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
enclosure
part of gas-insulated metal-enclosed switchgear retaining the insulating gas under the prescribed conditions
necessary to maintain safely the rated insulation level, protecting the equipment against external influences
and providing a high degree of protection to personnel
3.2
manufacturer
organisation that is responsible for the design of the enclosure and the production of the gas-insulated
switchgear. In this standard this is the switchgear manufacturer
3.3
founder
organisation that produces the raw casting of the enclosure
3.4
design pressure
pressure, expressed in relative terms (gauge), used to determine the thickness of the enclosure
Note 1 to entry: It is at least equal to the maximum pressure in the enclosure at the highest temperature that the gas
used for insulation can reach under specified maximum service conditions.
3.5
design temperature (of an enclosure)
maximum temperature that the enclosures can reach under specified maximum service conditions
[SOURCE: 3.112, EN 62271-203:2012]
Note 1 to entry: This is generally the upper limit of ambient air temperature increased by the temperature rise due to
the flow of rated normal current.
Note 2 to entry: Solar radiation should be taken into account when it has a significant effect on the temperature of the
gas and on the mechanical properties of materials. Similarly, the effects of low temperatures on the properties of
materials should be considered.
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3.6
design stress
maximum permissible stress on the enclosure imposed by conditions of operation, environment or test that
determine the (material) characteristics of an enclosure
3.7
normal load
load whose occurrence and level can be planned or predicted
3.8
exceptional load
load whose probability of occurrence during the lifetime of product is very small or accidental
3.9
casting
product at or near finished shape, formed by solidification of the metal in a mould or a die
[SOURCE: EN 12258-1:2012, 2.5.1]
3.10
melt
quantity of molten metal that has simultaneously undergone the same preparatory treatment in the furnace
before the casting operation
[SOURCE: EN 12258-1:2012, 4.1.3]
3.11
alloy
substance having metallic properties and composed of two or more elements so combined that they cannot
readily be separated by physical means
[SOURCE: EN 12258-1:2012, 2.2.1]
3.12
casting defect
imperfections in castings after solidification
3.12.1
cold shut
linear discontinuity in a cast surface caused by freezing of the melt meniscus in contact with the mould and
the liquid metal flowing over the solidified metal
[SOURCE: EN 12258-1:2012, 5.2.1]
3.12.2
cold crack
crack in cast metal initiated by mechanical stresses at temperatures significantly below the solidus
temperature
[SOURCE: EN 12258-1:2012, 5.2.9]
3.12.3
hot crack (hot tear)
crack formed in a cast metal or in a welding because of internal stress developed upon cooling at the solidus
temperature or slightly above
[SOURCE: EN 12258-1:2012, 5.2.8]
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3.12.4
inclusion
extraneous material accidentally entrapped into the liquid metal during melting or melt treatment or
entrapped into the metal surface during hot or cold working
[SOURCE: EN 12258-1:2012, 5.5.7]
3.12.5
blister
raised spot whose inside is hollow, that forms on the surface of products and is caused by the penetration of
a gas into a subsurface zone typically during thermal treatment
[SOURCE: EN 12258-1:2012, 5.5.10]
Note 1 to entry: A void resulting from blister that has ruptured is often termed “blow hole”.
3.13
weld defect
imperfections in metallic fusion welds
3.13.1
lack of fusion
lack of union between the weld metal and the parent material or between the successive layers of weld metal
[SOURCE: EN ISO 6520-1:2007, Reference No. 401]
3.13.2
overlap
excessive weld metal covering the parent material surface but not fused to it
[SOURCE: EN ISO 6520-1:2007, Reference No. 506]
3.13.3
undercut
irregular groove at a toe of a run in the parent material or in previously deposited weld metal
[SOURCE: EN ISO 6520-1:2007, Reference No. 501]
3.14
thermal treatment
heating, holding at elevated temperature and cooling of the solid metal in such a way as to obtain desired
metallurgical structure or properties
[SOURCE: EN 12258-1:2012, 3.6.1]
Note 1 to entry: The term “heat treatment” is used for the same concept as a synonym.
3.15
ductility
ability of a material to deform plastically before fracturing
[SOURCE: EN 12258-1:2012, 4.3.15]
3.16
fatigue
tendency for a metal to break under conditions of repeated cyclic stressing considerably below the tensile
strength
[SOURCE: EN 12258-1:2012, 4.3.23]
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3.17
tensile strength
ratio of maximum load before rupture in a tensile test to original cross-sectional area
[SOURCE: EN 12258-1:2012, 4.3.3]
3.18
yield stress
stress necessary to produce a defined small plastic deformation in a material under uniaxial tensile or
compressive load
[SOURCE: EN 12258-1:2012, 4.3.4, modified]
3.19
test piece
two or more parts of material welded together in accordance with a specified weld procedure, or a portion of
a casting taken in order to make one or more test specimens
3.20
test specimen
portion detached from a test piece, in specified dimensions, finally prepared as required for testing
4 Materials
4.1 Selection of material
Any suitable cast aluminium alloy is permissible; a list of recommended materials is given in Table 1.
Table 1 — List of recommended cast aluminium alloys [1]
EN AC- EN AC- EN AC- EN AC-
Alloy
AlSi7Mg0.3 AlSi9Mg AlSi10Mg(a) AlSi12(a)
Europe EN 1706
EN AC -
Coding EN AC - 42100 EN AC - 43300 EN AC - 43000
44200
Internatio
ISO 3522 Alloy AlSi7Mg0.3 AlSi9Mg AlSi10Mg AlSi12(a)
nal
Register
USA Coding A356.0   B413.0
Record
Alloy ZAlSi7MgA  ZALSi9Mg
China GB/T 1173
Coding ZL 101A  ZL 104
India IS 202, IS 617 Coding 4458  4535 4700
Japan JIS H5202 Alloy AC4CH  Al-Si10Mg Al-Si12
Canada CSA.HA.3 Alloy SG70N (old)  SC84 (old) Sn12 (old)
Australia AS 1874 Coding AA601   CA401
GOST 1583
Russia (old : Coding AL9–1 (old) AL4–1 (old) AL4 (old) AL2 (old)
GOST 2685)
These alloys are recommended because of their low content of copper and zinc (lower than 0,5 % each) as
well as their low content of magnesium (lower than 0,7 %).
Alloys listed in this table are similar but not identical regarding chemical composition and mechanical
properties. They are not interchangeable without a re-qualification of the enclosure; i.e. re-calculation or re-
testing.
The properties of the materials should be taken from the applicable standards.
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For applications where specified temperatures exceed 100 °C heat treated materials are not permitted due to
the loss of material properties, i.e. the thermal treatment will be nullified.
4.2 Chemical analysis
Ingots used shall comply with the requirements of the appropriate material specification and any special
requirement called for on the order; they shall be clean and free from harmful defects.
Providing the chemical analysis of the melt meets the requirements of the appropriate specification, the
founder may use scrap which arises from his own production from approved ingots, which is segregated and
identifiable. It may include heavy fettling scrap, but shall exclude all drosses and small particles such as
sawings and chippings.
NOTE 1 Attention is drawn to a limitation of the range of aluminium-magnesium alloys. Alloys with magnesium
content above 0,7 % can become susceptible to stress-corrosion cracking after use for long periods at temperatures
above 66 °C.
NOTE 2 Contact with more noble metals, particularly copper and its alloys, can lead to heavy galvanic corrosion.
Austenitic stainless steel is an exception to this rule because of its protective oxide film, and can often be used in contact
with aluminium. If necessary, aluminium enclosures should be protected where, for example, they come into contact with
mild steel supports. Zinc chromate paint, bitumen, thin zinc sheet (which gives sacrificial protection) or a combination of
these are useful in this respect. Alternatively, the mild steel supports can be galvanized or zinc
...