EN 50464-1:2007

SLOVENSKI STANDARD
01-december-2007
1DGRPHãþD
SIST HD 428.1 S1:1997
SIST HD 428.1 S1:1997/A1:1997
SIST HD 428.3 S1:1997
Trifazni oljni distribucijski transformatorji od 50 do 2500 kVA, 50 Hz z najvišjo
napetostjo naprave do 36 kV - 1. del: Splošne zahteve
Three-phase oil-immersed distribution transformers 50 Hz, from 50 kVA to 2 500 kVA
with highest voltage for equipment not exceeding 36 kV -- Part 1: General requirements
Ölgefüllte Drehstrom-Verteilungstransformatoren 50 Hz, 50 kVA bis 2 500 kVA, mit einer
höchsten Spannung für Betriebsmittel bis 36 kV -- Teil 1: Allgemeine Anforderungen
Transformateurs triphasés de distribution immergés dans l'huile, 50 Hz, de 50 kVA a 2
500 kVA, de tension la plus élevée pour le matériel ne dépassant pas 36 kV -- Partie 1:
Prescriptions générales
Ta slovenski standard je istoveten z: EN 50464-1:2007
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 50464-1
NORME EUROPÉENNE
April 2007
EUROPÄISCHE NORM
ICS 29.180 Supersedes HD 428.1 S1:1992 + A1:1995 and HD 428.3 S1:1994

English version
Three-phase oil-immersed distribution transformers 50 Hz,
from 50 kVA to 2 500 kVA with highest voltage
for equipment not exceeding 36 kV -
Part 1: General requirements
Transformateurs triphasés de distribution Ölgefüllte
immergés dans l'huile, Drehstrom-Verteilungstransformatoren
50 Hz, de 50 kVA à 2 500 kVA, 50 Hz, 50 kVA bis 2 500 kVA,
de tension la plus élevée mit einer höchsten Spannung
pour le matériel ne dépassant pas 36 kV - für Betriebsmittel bis 36 kV -
Partie 1: Prescriptions générales Teil 1: Allgemeine Anforderungen

This European Standard was approved by CENELEC on 2006-12-01. 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

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50464-1:2007 E
Foreword
This European Standard, prepared by the Technical Committee CENELEC TC 14, Power transformers
was submitted to the formal vote and was approved by CENELEC as EN 50464-1 on 2006-12-01.
This European Standard supersedes HD 428.1 S1:1992 + A1:1995 and HD 428.3 S1:1994.
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) 2007-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-12-01
The EN 50464 series consists of the following parts, under the general title “Three-phase oil-immersed
distribution transformers 50 Hz, from 50 kVA to 2 500 kVA with highest voltage for equipment not
exceeding 36 kV”:
Part 1 General requirements
Part 2-1 Distribution transformers with cable boxes on the high-voltage and/or low-voltage
side – General requirements
Part 2-2 Distribution transformers with cable boxes on the high-voltage and/or low-voltage
side – Cable boxes type 1 for use on distribution transformers meeting the
requirements of EN 50464-2-1
Part 2-3 Distribution transformers with cable boxes on the high-voltage and/or low-voltage
side – Cable boxes type 2 for use on distribution transformers meeting the
requirements of EN 50464-2-1
Part 3 Determination of the power rating of a transformer loaded with non-sinusoidal
currents
Part 4 Requirements and tests concerning pressurised corrugated tanks
__________
- 3 - EN 50464-1:2007
Contents
1 Scope. 4
2 Normative references . 4
3 Electrical characteristics . 4
3.1 Rated power. 4
3.2 Highest voltages for equipment for windings . 5
3.3 Rated voltages of windings . 5
3.4 Tapping . 5
3.5 Connections . 5
3.6 Dimensioning of neutral connection of the low-voltage winding . 6
3.7 Short-circuit impedance . 6
3.8 Losses and sound power level. 6
3.9 Tolerances and penalties . 10
3.10 Tests . 10
3.11 Insulation levels and dielectric tests . 10
4 Design requirements . 10
4.1 Type of oil preservation system and degree of sealing. 10
4.2 Terminal markings . 10
4.3 Terminations . 10
4.4 Distance between bushings. 11
4.5 Rollers . 11
5 Accessories . 11
6 Efficiency and voltage drop (at reference temperature). 12
6.1 Efficiency . 12
6.2 Voltage drop ( u%) . 13
Annex A (informative) Capitalisation evaluation. 14
Bibliography. 15
Tables
Table 1 – Connections for distribution transformers. 5
Table 2 – Load losses P (W) at 75 °C for U 24 kV. 7
k m
Table 3 – No load losses P (W) and sound power level (Lw ) for U 24 kV. 8
0 (A) m
Table 4 – Load losses P (W) at 75 °C for U = 36 kV . 9
k36 m
Table 5 – No load losses P (W) and sound power level (Lw ) for U = 36 kV . 9
036 (A) m
Table 6 – Accessories . 12

1 Scope
This document covers transformers from 50 kVA to 2 500 kVA intended for operation in three-phase
distribution networks, for indoor or outdoor continuous service, 50 Hz, immersed in mineral oil, natural
cooling, with two windings:
− a primary (high-voltage) winding with a highest voltage for equipment from 3,6 kV to 36 kV;
− a secondary (low-voltage) winding with a highest voltage for equipment not exceeding 1,1 kV.
NOTE 1 This document may be applied, either as a whole or in part, to transformers immersed in a synthetic insulating liquid.
NOTE 2 This document may be applied, either as whole or in part, to transformers having windings with more than one rated
voltage. In this case the rated power for each rated voltage shall be specified by the purchaser.
The object of this document is to lay down requirements related to electrical characteristics and design of
three phases distribution transformers immersed in mineral oil.
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 50216 series Power transformer and reactor fittings
EN 50464-2 series Three-phase oil-immersed distribution transformers 50 Hz, from 50 kVA
to 2500 kVA with highest voltage for equipment not exceeding 36 kV
EN 60076 series Power transformers (IEC 60076 series)
IEC/TR 60616 Terminal and tapping markings for power transformers
3 Electrical characteristics
3.1 Rated power
The values of the rated power are
50 kVA – 100 kVA – 160 kVA – 250 kVA – 315 kVA – 400 kVA – 500 kVA – 630 kVA –
800 kVA – 1 000 kVA – 1 250 kVA – 1 600 kVA – 2 000 kVA – 2 500 kVA.
The underlined values are preferred.

- 5 - EN 50464-1:2007
3.2 Highest voltages for equipment for windings
Insulation levels and dielectric tests shall be in accordance with the requirements of EN 60076-3.
The values of the highest voltage for equipment are
− for the high-voltage winding:
3,6 kV– 7,2 kV – 12 kV – 17,5 kV – 24 kV – 36 kV,
− for the low-voltage winding:
1,1 kV.
3.3 Rated voltages of windings
3.3.1 For the high-voltage winding
The rated value of the high voltage winding is above 1,1 kV, up to and including 36 kV.
3.3.2 For the low-voltage winding
The rated voltage shall be chosen among the following preferred values:
400 V – 410 V – 415 V – 420 V – 433 V.
NOTE This document may be applied, either as a whole or in part, to transformers with rated low voltages below 400 V and above
433 V.
3.4 Tapping
The HV winding can be provided with tapping. The preferred tapping ranges are ± 2,5 % or ± 2 x 2,5 %
unless otherwise specified ,but in any case maximum taps shall not exceed 7 positions and the total
maximum range shall not exceed 15 %.
The tapping range has to be specified by the purchaser or by agreement between manufacturer and
purchaser.
These taps shall be connected to an off-circuit tapping switch.
3.5 Connections
Connections shall be made in accordance with the provisions of Table 1.
Table 1 – Connections for distribution transformers
Rated power
50 and 100 ≥ 160
kVA
U ≤ 24 kV Y zn or D yn D yn
m
U = 36 kV Y zn or D yn D yn
m
The clock hour figure shall be 5 or 11.
Connection symbol Y zn 5 ; Y zn 11 ; D yn 5 ; D yn 11.

Connections and clock figure shall be specified by the purchaser.
NOTE This document may be applied, either as a whole or in part, to transformers having connections other than those mentioned
above.
3.6 Dimensioning of neutral connection of the low-voltage winding
The neutral conductor and terminal of the low-voltage winding shall be dimensioned for rated current and
earth fault current, unless otherwise specified.
3.7 Short-circuit impedance
The preferred values of the short-circuit impedance at a reference temperature of 75 °C are
− for rated voltage ≤ 24 kV (refer to Table 2),
− for rated voltage = 36 kV (refer to Table 4).
NOTE Other values of short-circuit impedance may be specified by the purchaser for particular system service conditions, e.g. in
the case of parallel options.
3.8 Losses and sound power level
For transformers having listed values of rated power and preferred value of short-circuit impedance in
accordance with 3.1 and 3.7, the values of losses and sound power levels are stated, for U ≤ 24 kV, in
m
Table 2 (load losses) and Table 3 (no load losses and sound power levels), for U = 36 kV in Table 4
m
(load losses) and Table 5 (no load losses and sound power levels).
The sound power levels given in Table 3 for U ≤ 24 kV and in Table 5 for U = 36 kV are the maximum
m m
admitted (no tolerance). Lower sound power levels can be specified by the purchaser.
To choose the correct load losses (Table 2 or Table 4) and no load losses (Table 3 or Table 5) or when
the loss values stated in the tables do not correspond to the actual evaluation of the energy cost, the
transformers can be requested and offered with losses differing from the tabled losses; the capitalisation
formula given in annex is applicable.
3.8.1 Load losses, no load losses and sound power level for U 24 kV
m
In the following tables, column A values correspond to the lowest losses as commonly used in EU for
electrical devices.
Transformers can be requested and offered with L lower than the tabled values.
wA
A “low noise” series with no load losses E , D , C or B can be proposed with the L from the tabled
o o o o wA
values of D , C , B or A respectively.
o o o o
- 7 - EN 50464-1:2007
Table 2 – Load losses P (W) at 75 °C for U 24 kV
k m
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