kSIST FprEN IEC 60310:2026
(Main)Railway applications - Traction transformers and inductors on board rolling stock
Railway applications - Traction transformers and inductors on board rolling stock
Bahnanwendungen - Bahn-Transformatoren und Drosselspulen auf Schienenfahrzeugen
Applications ferroviaires - Transformateurs de traction et bobines d'inductance à bord du matériel roulant
Železniške naprave - Transformatorji in dušilke vlečnih tokokrogov na tirnih vozilih
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN IEC 60310:2025
01-februar-2025
Železniške naprave - Transformatorji in dušilke vlečnih tokokrogov na voznih
sredstvih
Railway applications - Traction transformers and inductors on board rolling stock
Applications ferroviaires - Transformateurs de traction et bobines d'inductance à bord du
matériel roulant
Ta slovenski standard je istoveten z: prEN IEC 60310:2024
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
45.060.10 Vlečna vozila Tractive stock
oSIST prEN IEC 60310:2025 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN IEC 60310:2025
oSIST prEN IEC 60310:2025
9/3150/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60310 ED5
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2024-12-20 2025-03-14
SUPERSEDES DOCUMENTS:
9/3051/CD, 9/3111A/CC
IEC TC 9 : ELECTRICAL EQUIPMENT AND SYSTEMS FOR RAILWAYS
SECRETARIAT: SECRETARY:
France Mr Denis MIGLIANICO
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of CENELEC,
is drawn to the fact that this Committee Draft for Vote (CDV) is
submitted for parallel voting.
The CENELEC members are invited to vote through the CENELEC
online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clauses to be
included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC clauses. (SEE
AC/22/2007 OR NEW GUIDANCE DOC).
TITLE:
Railway applications – Traction transformers and inductors on board rolling stock
PROPOSED STABILITY DATE: 2030
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.
oSIST prEN IEC 60310:2025
9/3150/CDV – 2 – IEC CDV 60310 © IEC 2024
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviations . 9
4 Classification . 14
4.1 General . 14
4.2 Classification of transformers . 15
4.3 Classification of inductors . 16
5 Service conditions . 16
6 Rated current and load profile . 16
6.1 Load profile . 16
6.2 Rated current . 16
7 Rated voltage and power of transformer windings . 17
7.1 Rated line-side voltage . 17
7.2 Rated secondary voltage . 17
7.3 Rated power of transformer. 17
8 Transformer tappings . 17
9 Cooling . 17
9.1 Identification of transformers and inductors according to cooling method . 17
9.2 Arrangement of symbols . 18
9.2.1 Enclosed transformers and inductors . 18
9.2.2 Non-enclosed transformers and inductors . 18
9.2.3 Air cooling . 19
10 Temperature limits . 19
10.1 Classification of insulating materials . 19
10.2 Temperature limits of solid insulation . 19
10.3 Temperature limits for liquid . 20
10.4 Temperature limits for other parts . 20
11 Mechanical design . 20
12 Fire protection . 21
13 Rating plates . 21
13.1 General . 21
13.2 Rating plates for transformer. 21
13.3 Rating plates for inductor . 21
14 Tests . 22
14.1 Categories of tests . 22
14.1.1 General . 22
14.1.2 Type tests. 22
14.1.3 Routine tests . 22
14.1.4 Investigation tests. 22
14.2 List of checks and tests . 23
14.3 Tolerances . 24
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14.3.1 Tolerances for transformer . 24
14.3.2 Tolerance for inductors . 25
14.4 Test items . 25
14.4.1 Visual checks . 25
14.4.2 Functional tests . 25
14.4.3 Mass . 26
14.4.4 Measurement of winding resistance . 26
14.4.5 Measurement of voltage ratio, polarities and vector groups. 27
14.4.6 Measurement of impedance voltages or short-circuit impedances . 27
14.4.7 Measurement of inductance . 27
14.4.8 Measurement of no-load primary current and losses . 30
14.4.9 Measurement of fundamental load losses . 31
14.4.10 Determination of losses . 32
14.4.11 Temperature-rise test . 32
14.4.12 Insulation resistance test . 37
14.4.13 Dielectric tests . 37
14.4.14 Partial discharge test . 43
14.4.15 Short-circuit withstand test . 46
14.4.16 Shock and vibration test . 48
14.4.17 Vibration test with current flowing . 50
14.4.18 Voltage Transmission Ratio (VTR) . 50
14.4.19 Noise measurement . 51
14.4.20 Leakage magnetic flux density measurement . 51
14.4.21 Electrical frequency response analysis (FRA) . 51
14.4.22 Inrush current measurement . 52
Annex A (informative) List of items for which an agreement between purchaser and
manufacturer is needed or for which further information or specifications shall be
given by the purchaser or by the manufacturer . 53
A.1 Items subject to agreement between purchaser and manufacturer . 53
A.1.1 Transformer and inductors . 53
A.1.2 Transformers . 54
A.1.3 Inductors. 55
A.2 Information to be given by purchaser to manufacturer . 55
A.2.1 Transformers and inductors . 55
A.2.2 Transformers . 57
A.2.3 Inductors. 57
A.3 Information to be given by manufacturer to purchaser . 57
A.3.1 Transformers and inductors . 57
A.3.2 Transformers . 58
A.3.3 Inductors. 58
Annex B (informative) Thermal ageing and insulation life time . 59
B.1 Insulation life time and thermal ageing . 59
B.2 Special considerations for thermal design and test. 59
B.2.1 General . 59
B.2.2 Cooling medium temperature at the external interface. 60
B.2.3 Rated current . 60
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B.2.4 Temperature rise test of a dry-type transformer/inductor . 60
B.3 Thermal conformity of the insulation system . 60
B.4 End of life criterion . 60
Annex C (informative) Example of thermal endurance calculation to demonstrate the
suitability of an insulation system for a specified application . 62
C.1 Preliminary . 62
C.2 Example 1 – Temperature limits for a dry-type transformer/inductor . 62
C.3 Example 2 – Thermal endurance calculation . 62
C.3.1 General . 62
C.3.2 Operating conditions to be provided by the purchaser . 62
C.3.3 Thermal endurance characteristics to be provided by the manufacturer . 63
C.3.4 Temperature rise test results . 63
C.3.5 Calculations . 64
Annex D (informative) Wet dielectric tests for dry-type transformers and inductors . 66
D.1 General . 66
D.2 Wet test 1 (optional type test or optional routine test): short soaking . 66
D.3 Wet test 2 (investigation test or optional type test): misting . 66
D.4 Wet test 3 (investigation test): thermal shock – long soaking – misting . 67
D.4.1 General . 67
D.4.2 Temperature conditioning . 67
D.4.3 Thermal shock . 67
D.4.4 Dielectric test . 67
D.5 Common test procedure and criteria for wet dielectric tests . 67
Annex E (informative) Load profiles . 69
Annex F (informative) Background of dielectric test voltages in IEC 60310 . 70
F.1 General . 70
F.2 Background . 70
Bibliography . 71
Figure 1 – Traction transformer with auxiliary windings fed by AC power supply system . 14
Figure 2 – Traction transformer without auxiliary windings fed by AC power supply
system . 15
Figure 3 – DC locomotive typical circuit diagram . 15
Figure 4 – Energy storage system typical circuit diagram . 15
Figure 5 – Examples of set up for induced voltage withstanding tests . 40
Figure 6 – Examples of set up for separate source voltage withstanding tests . 41
Figure 7 – Examples of impulse test connections for traction, inductor and auxiliary
transformers . 42
Figure 8 – Partial discharge test: voltage versus time . 44
Figure 9 – Configurations for VTR test . 51
Figure 10 – Example of test circuit . 52
Table 1 – Letter symbols for cooling method . 18
Table 2 – Order of symbols . 18
Table 3 – Temperature limits of solid insulation . 19
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Table 4 – Temperature limits for liquid . 20
Table 5 – List of checks and tests to be made on transformers and/or inductors . 23
Table 6 – Tolerances for transformer . 24
Table 7 – Tolerances for inductors . 25
Table 8 – Reference temperatures . 26
Table 9 – Dielectric test voltage . 39
Table 10 – Test method of voltage between terminals withstand test . 43
Table 11 – Partial discharge measurements. 45
Table C.1 – Temperature limits and expected lifetime for a dry-type transformer or
inductor (examples) . 62
Table C.2 – Load cycle histogram . 63
Table C.3 – Temperature histogram . 63
Table C.4 – Temperature rise test results . 63
Table C.5 – Thermal endurance calculation . 64
Table C.6 – Equivalent current and temperatures . 65
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
TRANSFORMERS AND INDUCTORS ON BOARD ROLLING STOCK
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC 60310 has been prepared by IEC technical committee 9: Electrical equipment and systems
for railways. It is an International Standard.
This fifth edition cancels and replaces the fourth edition published in 2016-01-27. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) typical circuits for transformer and inductors are added;
b) letter symbols for cooling methods are added;
c) dielectric test table is modified;
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d) Subclauses for the tests of transformers and inductors are restructured;
e) temperature test for dry type transformer and dry type inductors are separated in different
Sub-clauses;
f) requirements for shock and vibration tests are updated according to IEC 61373:202X.
The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
oSIST prEN IEC 60310:2025
9/3150/CDV – 8 – IEC CDV 60310 © IEC 2024
1 RAILWAY APPLICATIONS –
3 TRANSFORMERS AND INDUCTORS ON BOARD ROLLING STOCK
7 1 Scope
8 This document specified the terms and definition, classification, service condition,
9 characteristics and test methods for transformers and inductors on board rolling stock.
10 This document is applicable to traction and auxiliary power transformers installed on board
11 rolling stock and to the various types of power inductors inserted in the traction and auxiliary
12 circuits of rolling stock, of dry or liquid-immersed design.
13 This document is also applicable to the traction transformers of three-phase AC line-side
14 powered vehicles and to the transformers inserted in the single-phase or poly-phase auxiliary
15 circuits of vehicles, after agreement between purchaser and manufacturer.
16 This document does not apply to instrument transformers, transformers of a rated output below
17 1 kVA single-phase or 5 kVA poly-phase, and inductors of a rated output below 1 kVAR single-
18 phase or 5 kVAR poly-phase on board rolling stock.
19 This document does not cover accessories such as tap changers, resistors, heat exchangers,
20 fans, etc., intended for mounting on transformers or inductors, which are tested separately
21 according to the relevant rules.
22 NOTE Items requiring agreement between the delivery parties and items of supplementary information and
23 specification particulars to be provided by the ordering party or manufacturer are given in Annex A.
24 2 Normative references
25 The following documents are referred to in the text in such a way that some or all of their content
26 constitutes requirements of this document. For dated references, only the edition cited applies.
27 For undated references, the latest edition of the referenced document (including any
28 amendments) applies.
29 IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
30 IEC 60060-2, High-voltage test techniques – Part 2: Measuring systems
31 IEC 60076-1:2011, Power transformers – Part 1: General
32 IEC 60076-2, Power transformers – Part 2: Temperature rise for liquid-immersed transformers
33 IEC 60076-3, Power transformers – Part 3: Insulation levels, dielectric tests and external
34 clearances in air
35 IEC 60076-4, Power transformers – Part 4: Guide to the lightning impulse and switching impulse
36 testing – Power transformers and reactors
37 IEC 60076-5, Power transformers – Part 5: Ability to withstand short circuit
38 IEC 60076-6:2007, Power transformers – Part 6: Reactors
39 IEC 60076-7, Power transformers – Part 7: Loading guide for oil-immersed power transformers
40 IEC 60076-10, Power transformers – Part 10: Determination of sound levels
41 IEC 60076-11, Power transformers – Part 11: Dry-type transformers
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42 IEC 60076-12:2008, Power transformers – Part 12: Loading guide for dry-type transformers
43 IEC 60076-14, Power transformers – Part 14: Liquid-immersed power transformers using high-
44 temperature insulation materials
45 IEC 60076-18, Power transformers – Part 18: Measurement of frequency response
46 IEC 60077-1, Railway applications – Electric equipment for rolling stock – Part 1: General
47 service conditions and general rules
48 IEC 60085, Electrical insulation – Thermal evaluation and designation
49 IEC 60270, High-voltage test techniques – Partial discharge measurements
50 IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for
51 transformers and switchgear
52 IEC 60836, Specifications for unused silicone insulating liquids for electrotechnical purposes
53 IEC 60850, Railway applications – Supply voltage of traction systems
54 IEC 61039, Classification of insulating liquids
55 IEC 61099, Insulating liquids – Specifications for unused synthetic organic esters for electrical
56 purposes
57 IEC 61373:2010, Railway applications – Rolling stock equipment – Shock and vibration tests
58 IEC 61378-1:2011, Convertor transformers – Part 1: Transformers for industrial applications
59 IEC 62497-1, Railway applications – Insulation coordination – Part 1: Basic requirements –
60 Clearances and creepage distances for all electrical and electronic equipment
61 IEC 62498-1, Railway applications – Environmental conditions for equipment – Part 1:
62 Equipment on board rolling stock
63 ISO 3746, Acoustics – Determination of sound power levels and sound energy levels of noise
64 sources using sound pressure – Survey method using an enveloping measurement surface over
65 a reflecting plane
66 ISO 9614-1, Acoustics – Determination of sound power levels of noise sources using sound
67 intensity – Part 1: Measurement at discrete points
68 ISO 9614-2, Acoustics – Determination of sound power levels of noise sources using sound
69 intensity – Part 2: Measurement by scanning
70 3 Terms, definitions and abbreviations
71 For the purposes of this document, the terms and definitions given in IEC 60076-1, IEC 62497-
72 1 and the following apply.
73 ISO and IEC maintain terminology databases for use in standardization at the following
74 addresses:
75 • IEC Electropedia: available at https://www.electropedia.org/
76 • ISO Online browsing platform: available at https://www.iso.org/obp
77 NOTE 1 When the term “transformer” is used alone, it applies to both traction and auxiliary transformers.
78 NOTE 2 The term “transformer(s)/inductor(s)” appears in clauses applicable to both transformers and inductors to
79 avoid duplication of text.
80 NOTE 3 The term “inductor” is used in this document with the same meaning as the term “reactor” mentioned in
81 IEC 60050-421, IEC 60050-811 and IEC 60076-6.
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82 3.1 General definitions
83 3.1.1
84 traction transformer
85 transformers intended to supply the traction circuits, and optionally also other equipment
86 3.1.2
87 auxiliary transformer
88 transformers intended to supply electrical equipment except traction circuits
89 Note 1 to entry: In the energy storage system, the transformer supplying traction circuit is traction transformer, and
90 that supplying electrical equipment except traction circuit is auxiliary transformer.
91 3.1.3
92 inductor
93 two-terminal device characterized essentially by its inductance
94 [SOURCE: IEC 60050-151:2001, 151-13-25, modified – The notes to entry have been omitted.]
95 3.1.4
96 load profile
97 component output power / current versus time under specified conditions including voltage,
98 rectifier, configuration, harmonic content, etc.
99 Note 1 to entry: Efficiency for the transformer has to be agreed between the manufacture and purchaser.
100 3.1.5
101 short time emergency loading
102 unusually heavy loading of a transient nature (less than one time constant of the transformer)
103 occurring during degraded mode, such as a loss of one traction converter, etc.
104 [SOURCE: IEC 60076-12:2008, 3.2, modified]
105 3.1.6
106 cooling medium
107 medium used to extract the heat out of the transformer/inductor e.g. air, water, oil, heat sink,
108 etc.
109 3.1.7
110 rated insulation voltage
111 U
Nm
112 RMS withstand voltage value assigned by the manufacturer to the equipment or a part of it,
113 characterising the specified permanent (over 5 min) withstand capability of its insulation
114 Note 1 to entry: U is a voltage between a live part of equipment and earth or another live part. For rolling stock,
Nm
115 earth refers to the car body.
116 Note 2 to entry: For circuits, systems and sub-systems in railway applications this definition is preferred to "highest
117 voltage for equipment" which is widely used in international standards.
118 Note 3 to entry: U is higher than or equal to the working voltage. As a consequence, for circuits directly connected
Nm
119 to the contact line, U is equal to or higher than U as specified in IEC 60850. For circuits connected to electronic
Nm max1
120 converter U is higher than or equal to the DC link voltage.
Nm
121 Note 4 to entry: U is not necessarily equal to the rated voltage which is primarily related to functional
Nm
122 performance.
123 [SOURCE: IEC 60050-426:2020, 426-04-50, modified – “(long-term)” has been replaced with
124 “permanent (over 5 min)”. The note 1 to entry has been adapted and renumbered as note 4 to
125 entry. The notes 1, 2 and 3 to entry have been added.]
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126 3.1.8
127 nominal voltage
128 U
n
129 suitable approximate voltage used to designate or identify a given supply system
130 3.1.9
131 rated voltage
132 U
r
133 value of voltage assigned for a specific operating condition
134 3.1.10
135 rated impulse voltage
136 U
Ni
137 impulse voltage value, characterizing the specified withstand capability of its insulation against
138 transient over-voltages
139 3.1.11
140 test voltage
141 U
a
142 RMS value derived from U used for separate source voltage, induced voltage, voltage
Nm
143 between terminals withstand, depending on test carried out
144 3.1.12
145 recurring peak voltage
146 U , U
mT mG
147 maximum peak value of periodic excursions of the voltage waveform between terminals (U )
mT
148 or between terminals and ground (U )
mG
149 3.2 Definitions for transformers
150 3.2.1
151 voltage transmission ratio
152 VTR
153 ratio between the secondary voltage and the primary voltage when a specified impulse or AC
154 square voltage is applied on the primary
155 Note 1 to entry: The VTR is expressed as a percentage of this applied voltage.
156 3.2.2
157 impedance voltage
158 voltage applied to reach the rated current in short-circuit
159 Note 1 to entry: This is expressed as a percentage of this applied voltage to the rated voltage at reference
160 temperature.
161 Note 2 to entry: When expressed as a percentage or per unit, this is equal to the short circuit impedance referred
162 in IEC 60076-1:2011, 3.7.
163 3.2.3
164 tolerance
165 permitted deviation between the declared value of a quantity and the measured value
166 [SOURCE: IEC 60050-411:2007, 411-36-19]
167 3.3 Definitions for inductors
168 NOTE Values of inductance for inductors are related to the different classes of utilisation and are defined as follows,
169 with the understanding that they include an indication of the nature and value of the current used in their
170 measurement.
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171 3.3.1
172 AC inductance
173 inductance derived from the measurement of the alternating current carried by the inductor
174 when it is supplied by a sinusoidal alternating voltage of specified value and frequency
175 3.3.2
176 differential inductance
177 inductance defined from the derivative of the linked flux as a function of current (equal to the
178 slope of the magnetic characteristic)
179 Note 1 to entry: It is derived from the transient record of instantaneous voltage and current in the inductor or from
180 the measurement of the variation of magnetic flux.
181 3.3.3
182 incremental inductance
183 inductance seen by the AC current of a particular value and frequency superimposed on a direct
184 current through the inductor
185 Note 1 to entry: It should be mentioned that the ripple factor of a pulsating current, expressed as a percentage, is
186 conventionally defined by the formula:
I − I
max min
×100
I + I
max min
188 where I and I respectively represent the maximum and minimum values of the current wave.
max min
189 Note 2 to entry: It is derived from a record of the terminal voltage.
190 3.4 Definitions of thermal endurance
191 3.4.1
192 thermal endurance
193 time taken for the deterioration of a selected property (electrical, mechanical, etc.) to reach a
194 specified end-point at a given temperature
195 Note 1 to entry: An insulation material mainly ensures the electric performance (dielectric strength) of the conductor
196 insulation, while the impregnation, casting, sealing, coating, etc., materials mainly ensure the mechanical
197 performance of the windings (water tightness, resistance to thermal cycling and shock, resistance to vibration or
198 shocks, thermal conduction, etc.).
199 Note 2 to entry: An end-point of 50 % of the initial value of the property is used (unless otherwise specified).
200 3.4.2
201 temperature Index
202 TI
203 numerical value of the temperature (in degrees Celsius) derived from the thermal endurance
204 relationship at a time of 20 000 h (unless otherwise specified)
205 Note 1 to entry: TI is referring to the RTE (Relative Thermal Endurance) or ATE (Assessed Thermal Endurance)
206 indexes used in IEC 60216-5.
207 3.4.3
208 halving Interval
209 HIC
210 numerical value of the temperature interval (in Kelvins) which expresses the halving of the time
211 to end-point taken at the temperature equal to TI
212 [SOURCE: IEC 60050-212:2010, 212-12-11, modified – “corresponding to the temperature
213 index or the relative temperature index” has been replaced with ”equal to TI”.]
214 3.5 Definitions of thermal endurance calculations
215 NOTE As far as thermal endurance calculations are concerned, IEC 60076-12 provides an explanation of ageing
216 fundamentals and the means to estimate ageing rate and consumption of lifetime of the transformer/inductor
217 insulation as a function of operating temperature, time and loading. The hot-spot temperature is used to estimate the
218 number of hours of life time consumed during a particular time period of loading.
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219 3.5.1
220 thermal endurance in continuous operation
221 ECO
222 value derived from the simplified equation of the Arrhenius plot (based on TI and HIC) for a
223 given hotspot temperature θ (°C) as follows:
HS
TI −ϑ
HS
HIC
224 ECO(h) = 20 000× 2
225 Note 1 to entry: This simplified formula is very convenient to understand the concept of TI and HIC. However, this
226 formula yields slightly pessimistic results compared to the exact formula.
227 Note 2 to entry: Whenever possible, the exact Arrhenius formula derived from the endurance graph (constants A and
228 B) should be used, where E(h) is the thermal endurance and T (K) = θ (°C) 273,15 is the thermodynamic
HS HS
229 (absolute) hot-spot temperature:
B
230 logE(h) = log A +
T (K)
HS
231 which represents the thermal endurance graph, or
b
E(h) = a × exp
T
HS
233 which expresses directly the thermal endurance value.
234 3.5.2
235 actual operating time
236 AOT
237 actual time (in hours) the insulating system will operate at the given hotspot temperature
238 3.5.3
239 consumed endurance potential
240 CEP
241 ratio of actual operating time by consumed endurance potential for a given hotspot temperature
242 as follows:
AOT
CEP (%) = ×100
ECO
244 3.6 Abbreviations
245 For the purposes of this document, the following abbreviations apply:
246 AC alternating current
247 AOT actual operating time
248 ATE assessed thermal endurance
249 CEP consumed endurance potential
250 DC direct current
251 ECO thermal endurance in continuous operation
252 EIM electrical insulating material
253 EIS electrical insulating system
254 FEA finite element analysis
255 FRA frequency response analysis
256 HIC halving interval
257 HV high voltage
oSIST prEN IEC 60310:2025
9/3150/CDV – 14 – IEC CDV 60310 © IEC 2024
258 RMS root mean square
259 RTE relative thermal endurance
260 TI thermal index
261 VTR voltage transmission ratio
262 4 Classification
263 4.1 General
264 The traction transformer and auxiliary transformer could be integrated, i.e., the traction
265 transformers could have several secondary windings, such as traction windings, auxiliary
266 windings. Traction windings supply power to traction circuits. Auxiliary windings supply power
267 to auxiliary equipment.
268 NOTE In this document, the load side windings that feed the traction circuit and/or the auxiliary circuit used for other
269 purposes are collectively called “secondary windings”.
270 The typical circuits are described in this document to show the functions of each component.
271 Figure 1 shows the typical circuit diagram for traction transformer with auxiliary windings, and
272 Figure 2 shows that of separated traction and auxiliary transformers, while the traction
273 transformer is fed by AC power supply system, and the auxiliary transformer is fed by an inverter
274 connected to DC intermediate link. Figure 3 show the typical circuit diagram for auxiliary
275 transformer fed by DC power supply system. Figure 4 shows the typical circuit diagram for
276 traction transformer (Medium Frequency Transformer) fed by Energy Storage System such as
277 fuel cell battery system.
279 Figure 1 – Traction transformer with auxiliary windings fed by AC power supply system
oSIST prEN IEC 60310:2025
IEC CDV 60310 © IEC 2024 – 15 – 9/3150/CDV
281 Figure 2 – Traction transformer without auxiliary windings fed by AC power supply
282 system
284 Figure 3 – DC locomotive typical circuit diagram
286 Figure 4 – Energy storage system typical circuit diagram
287 4.2 Classification of transformers
288 The transformers mentioned above may be:
oSIST prEN IEC 60310:2025
9/3150/CDV – 16 – IEC CDV 60310 © IEC 2024
289 – traction transformers to supply the traction circuits, and optionally also other equipment;
290 – auxiliary transformers to supply electrical equipment except traction circuits.
291 Windings mentioned in the standard may be:
292 – line side windings which are directly connected to the power supply line;
293 – traction windings which supply the traction circuits;
294 – auxiliary windings which are used for o
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