SIST EN 50482:2008

SLOVENSKI STANDARD
SIST EN 50482:2008
01-maj-2008
1DGRPHãþD
SIST HD 587 S1:2001
Instrumentni transformatorji - Trifazni induktivni napetostni transformatorji z Um
do 52 kV
Instrument transformers - Three-phase inductive voltage transformers having Um up to
52 kV
Messwandler - Dreiphasige Spannungswandler mit Um bis 52 kV
Transformateurs de mesure - Transformateurs inductifs de tension triphasés avec Um
jusqu'à 52 kV
Ta slovenski standard je istoveten z: EN 50482:2008
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
SIST EN 50482:2008 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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EUROPEAN STANDARD
EN 50482

NORME EUROPÉENNE
January 2008
EUROPÄISCHE NORM

ICS 17.220.20 Supersedes HD 587 S1:1993


English version


Instrument transformers -
Three-phase inductive voltage transformers having U up to 52 kV
m



Transformateurs de mesure -  Messwandler -
Transformateurs inductifs de tension Dreiphasige Spannungswandler
triphasés avec U jusqu'à 52 kV mit U bis 52 kV
m m





This European Standard was approved by CENELEC on 2007-09-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50482:2008 E

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EN 50482:2008 – 2 –
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 38X, Instrument
transformers.
The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50482 on
2007-09-01.
This European Standard supersedes HD 587 S1:1993. It is to be used in conjunction with
EN 60044-2:1999.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-09-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-09-01
__________

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– 3 – EN 50482:2008
Contents
1 General. 5
1.1 Scope. 5
1.2 Normative references . 5
2 Definitions . 5
3 General requirements. 5
4 Normal and special service conditions. 5
5 Ratings. 5
5.1 Standard values of rated voltages. 5
5.2 Standard values of rated output. 6
5.3 Standard values of rated voltage factor. 6
5.4 Limits of temperature rise . 6
6 Design requirements . 7
6.1 Insulation requirements . 7
6.2 Short-circuit withstand capability. 8
7 Classification of tests. 8
8 Type tests . 8
8.1 Temperature-rise tests. 8
8.2 Short-circuit withstand capability test . 8
8.3 Impulse test on primary winding. 8
8.4 Wet test for outdoor type transformers. 9
9 Routine tests. 9
9.1 Verification of terminal markings. 9
9.2 Power frequency tests on primary winding and partial discharge measurement. 9
9.3 Power-frequency tests between section and on secondary windings. 11
10 Special test . 11
11 Markings . 11
11.1 Rating plate and markings . 11
11.2 Terminal markings. 11
12 Accuracy requirements for three-phase inductive measuring voltage transformers. 12
12.1 Accuracy class designation for measuring voltage transformers. 12
12.2 Limits of voltage error and phase displacement for measuring voltage transformers. 12
12.3 Type test for accuracy of measuring voltage transformers. 12
12.4 Routine test for accuracy of measuring voltage transformers . 12
12.5 Markings of the rating plate of three-phase measuring voltage transformer . 12
13 Additional requirements for three-phase inductive protective voltage transformers . 12
13.1 Accuracy class designation for protective voltage transformers. 12
13.2 Limits of voltage error and phase displacement for protective voltage transformers. 12
13.3 Rated voltages for secondary windings intended to produce a residual voltage. 12
13.4 Output for secondary windings intended to produce a residual voltage. 12
13.5 Accuracy class for secondary windings intended to produce a residual voltage. 13
13.6 Type test for protective voltage transformers. 13
13.7 Routine test for protective transformers . 14
13.8 Markings of the rating plate of a three-phase protective voltage transformer . 14
Bibliography . 21

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EN 50482:2008 – 4 –
Figures
Figure 1 – Three-phase transformer with a single secondary . 15
Figure 2 – Three-phase transformer with two secondaries . 15
Figure 3 – Three-phase transformer with one multi-tap secondary . 16
Figure 4 – Three-phase transformer with one residual voltage winding . 16
Figure 5 – Circuit for accuracy test on a voltage transformer having a rated voltage factor of 1,5 . 17
Figure 6 – Circuit for accuracy test on a voltage transformer having a rated voltage factor of 1,9 . 17
Figure 7 – Circuit for accuracy test on the residual voltage winding of a voltage transformer having
a rated voltage factor not exceeding 1,5 . 18
Figure 8 – Circuit for accuracy test on the residual voltage winding of a voltage transformer having
a rated voltage factor not exceeding 1,9 . 18
Figure 9 – Alternative circuit for accuracy test on the residual voltage winding of a voltage
transformer having a rated voltage factor of 1,9 . 19
Figure 10 – Test circuit for partial discharge measurement of a three-phase earthed voltage
transformer. 19
Figure 11 – Test circuit for partial discharge measurement of a three-phase unearthed voltage
transformer. 20
Figure 12 – Example of a calibration circuit used during the measurement of partial discharge
of a three-phase voltage transformer . 20
Table
Table 1 – Permissible partial discharge levels for various neutral earthing system and test voltages . 7

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– 5 – EN 50482:2008
1 General
1.1 Scope
This European Standard specifies the requirements and tests for new three-phase voltage transformers with
U up to 52 kV and frequencies from 15 Hz to 100 Hz, for use with electrical instruments or electrical
m
protective devices.
NOTE Single-phase voltage transformers connected in a three-phase bank are not covered in this document.
1.2 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.
EN 60044-2:1999, Instrument transformers – Part 2: Inductive voltage transformers
(IEC 60044-2:1997, mod.)
EN 60270:2001, High-voltage test techniques – Partial discharge measurements (IEC 60270:2000)
HD 588.1 S1:1991, High-voltage test techniques – Part 1: General definitions and test requirements
(IEC 60060-1:1989 + corr. March 1990)
2 Definitions
Clause 2 of EN 60044-2:1999 is applicable with the following additions:
2.3 Additional definitions for three-phase inductive voltage transformers
2.3.1
three-phase voltage transformer
a voltage transformer which has three line-to-neutral primary windings the neutral point of which can be
earthed or unearthed and in which one or more of the three line-to-neutral secondary windings can be
connected for three-phase operation or residual voltage operation
2.3.2
rated output of a three-phase voltage transformer
the per phase value of the apparent power (in volt-amperes at a specified power factor) that a
three-phase voltage transformer is intended to supply to the secondary circuit, at the rated secondary
voltage and with rated per-phase burden connected to it
3 General requirements
Clause 3 of EN 60044-2:1999 applies.
4 Normal and special service conditions
Clause 4 of EN 60044-2:1999 applies.
5 Ratings
5.1 Standard values of rated voltages
5.1.1 Rated primary voltages
The standard values of rated line-to-line primary voltage of three-phase voltage transformer shall be one
of the values of nominal system voltage designated by EN 60044-2:1999.
NOTE The performance of a voltage transformer as a measuring or protection transformer is based on the rated primary voltage,
whereas the rated insulation level is based on one value of the highest voltages for equipment of EN 60071.

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EN 50482:2008 – 6 –
5.1.2 Rated secondary voltages
The rated line-to-line secondary voltage shall be chosen according to practice at the location where the
transformer is to be used. The values given below are considered standard values for three-phase
voltage transformers:
– 100 V and 110 V;
– 200 V, for extended secondary circuits.
NOTE Whenever possible, the rated transformation ratio should be a simple value. If one of the following values: 10 – 12 – 15 – 20
– 25 – 30 – 40 – 50 – 60 – 80 and their decimal multiples is used for the rated transformation ratio together with one of the rated
secondary voltages of this subclause, the majority of the standard values of nominal system voltage of IEC 60038 will be covered.
5.1.3 Rated secondary voltages for residual windings
The rated secondary voltages of windings intended to be connected in broken-delta with similar windings
to produce a residual voltage are given in 13.3.
5.2 Standard values of rated output
The standard values of rated output per phase at a power factor of 0,8 lagging, expressed in
volt-amperes, are:
10 – 15 – 25 – 30 – 50 – 75 – 100 – 150 – 200 VA
The underlined values are preferred values.
NOTE For a given transformer, provided one of the values of rated output is standard and associated with a standard accuracy
class, the declaration of other rated outputs, which may be non-standard values but associated with other standard accuracy
classes, is not precluded.
5.3 Standard values of rated voltage factor
Subclause 5.3 of EN 60044-2:1999 applies.
5.4 Limits of temperature rise
Unless otherwise specified below the temperature rise of a voltage transformer at the specified voltage, at
the rated frequency and at the rated burden or at the highest burden, if there are several rated burden, at
any power factor between 0,8 lagging and unity, shall not exceed the appropriate value given in Table 3
of EN 60044-2:1999.
a) All three-phase transformers, irrespective of voltage factor (VF) and time rating, shall be capable of
operating continuously with a balanced three-phase voltage of 1,2 times rated primary voltage. The
steady state temperature rise shall not exceed the limits given in Table 3 of EN 60044-2:1999.
b) Three-phase earthed transformers having a voltage factor of 1,5 for 30 s or 1,9 for 30 s shall after the
application of 1,2 times rated primary voltages for sufficient time to reach stable thermal conditions,
be capable of operating with a balanced three-phase voltage of respectively 0,866 or 1,1 times the
rated primary voltage applied for 30 s, one line terminal of the primary winding being connected to the
neutral of that winding. The temperature rise shall not exceed by more than 10 K the value specified
in Table 3 of EN 60044-2:1999.
c) Three-phase earthed transformers having a voltage factor of 1,9 for 8 h shall after the application of
1,2 times rated primary voltage for sufficient time to reach stable thermal conditions, be capable of
operating with a balanced three-phase voltage of 1,1 times rated line-to-line voltage applied for 8 h,
one line terminal of the primary winding being connected to the neutral point of the winding. The
temperature rise shall not exceed by more than 10 K the value specified in Table 3 of
EN 60044-2:1999.
Table 3 of EN 60044-2:1999 as well as the text and the notes, except a), b), and c) above apply.

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– 7 – EN 50482:2008
6 Design requirements
6.1 Insulation requirements
These requirements apply to all types of inductive voltage transformers. For gas-insulated voltage
transformers supplementary requirements may be necessary (presently under consideration in
IEC/TC 38).
6.1.1 Rated insulation levels, primary windings
The rated insulation level shall be one of those given in Table 4 of EN 60044-2:1999.
6.1.2 Other requirements for primary winding insulation
6.1.2.1 Power-frequency withstand voltage
Subclause 6.1.2.1 of EN 60044-2:1999 applies.
6.1.2.2 Power-frequency withstand voltage for earthed terminal
Subclause 6.1.2.2 of EN 60044-2:1999 applies.
6.1.2.3 Partial discharges
Partial discharge requirements are applicable to inductive three-phase voltage transformers having U
m
greater than or equal to 7,2 kV. The partial discharge level shall not exceed the limits specified in Table 1,
at the partial discharge test voltages specified in the same table after prestressing according to the
procedures of 9.2.3.3.
Table 1 – Permissible partial discharge levels for various neutral earthing system and test voltages
Type of network Type of voltage Single-phase partial Permissible partial
earthing transformer discharge test voltage discharge level
pC
U 50
m
Earthed transformer
Earthed neutral system
1,2 U / √ 3 20
m

U 50
m
VF ≤ 1,5
Unearthed transformer
20
1,2 U / √ 3
m
U 50
m
Isolated or non-effectively Earthed transformer
20
1,2 U / √ 3
m
earthed neutral system

U 50
m
VF > 1,5 Unearthed transformer
20
1,2 U / √ 3
m
6.1.2.4 Chopped lighting-impulse
Subclause 6.1.2.4 of EN 60044-2:1999 applies.
6.1.3 Between-section insulation requirements
Subclause 6.1.3 of EN 60044-2:1999 applies.
6.1.4 Insulation requirements for secondary windings
Subclause 6.1.4 of EN 60044-2:1999 applies.

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EN 50482:2008 – 8 –
6.1.5 Requirements for external insulation
6.1.5.1 Pollution
For outdoor inductive voltage transformers, with ceramic insulators, susceptible to contamination, the
creepage distances for given pollution levels are given in Table 8 of EN 60044-2:1999.
6.2 Short-circuit withstand capability
The voltage transformer shall be designed and constructed to withstand without damage, when energized
at rated voltage, the mechanical and thermal effects of an external three-phase short-circuit for the duration
of 1 s.
7 Classification of tests
Clause 7 of EN 60044-2:1999 applies.
8 Type tests
8.1 Temperature-rise tests
Sub
...