prEN IEC 60076-4:2023

SLOVENSKI STANDARD
01-september-2023
Močnostni transformatorji - 4. del: Vodilo za testiranje impulza strele in
preklopnega impulza - Močnostni transformatorji in dušilke
Power transformers - Part 4: Guide to the lightning impulse and switching impulse testing
- Power transformers and reactors
Leistungstransformatoren - Teil 4: Leitfaden zur Blitz- und Schaltstoßspannungsprüfung
von Leistungstransformatoren und Drosselspulen
Transformateurs de puissance - Partie 4: Guide pour les essais au choc de foudre et au
choc de manoeuvre - Transformateurs de puissance et bobines d'inductance
Ta slovenski standard je istoveten z: prEN IEC 60076-4:2023
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

14/1109/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60076-4 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2023-07-07 2023-09-29
SUPERSEDES DOCUMENTS:
14/1060/CD, 14/1061C/CC
IEC TC 14 : POWER TRANSFORMERS
SECRETARIAT: SECRETARY:
United Kingdom Ms Stephanie Lavy
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

Other TC/SCs are requested to indicate their interest, if any,
in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
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.
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Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries”
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submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Power transformers - Part 4: Guide to the lightning impulse and switching impulse testing - Power
transformers and reactors
PROPOSED STABILITY DATE: 2026
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.

IEC CD 60076-4  IEC:2020 – 2 –
NOTE FROM TC/SC OFFICERS:
IEC CD 60076-4  IEC:2020 – 3 –
1 POWER TRANSFORMERS
3 Part 4: Lightning impulse and Switching impulse Tests
4 of Power Transformers and Reactors
6 FOREWORD
7 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national
8 electrotechnical committees (IEC National Committees). The object of the IEC is to promote international co-operation on
9 all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities,
10 the IEC publishes International Standards. Their preparation is entrusted to technical committees; any IEC National
11 Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and
12 non-governmental organizations liaising with the IEC also participate in this preparation. The IEC collaborates closely with
13 the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between
14 the two organizations.
15 2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an international
16 consensus of opinion on the relevant subjects since each technical committee has representation from all interested
17 National Committees.
18 3) The documents produced have the form of recommendations for international use and are published in the form of
19 standards, technical specifications, technical reports or guides and they are accepted by the National Committees in that
20 sense.
21 4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards
22 transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC
23 Standard and the corresponding national or regional standard shall be clearly indicated in the latter.
24 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment
25 declared to be in conformity with one of its standards.
26 6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent
27 rights. The IEC shall not be held responsible for identifying any or all such patent rights.
28 International Standard IEC 60076-4 has been prepared by IEC technical committee 14: Power
29 transformers.
This International Standard cancels and replaces the first edition published in 2002 and constitutes a
technical revision of that document.
30 This edition includes the following technical changes with respect to the previous
edition:
• Lightning impulse tests in presence of a relative overshoot value of 5% and higher (Clause 7.1.2).
• Test voltage function when performing chopped wave (Clause 7.2.1.1).
• Switching impulse tests on 3 phase transformers, test connections (Figure 5 and Figure 6)
• Glaninger circuit, clause A.3 (Annex A).
• New Annex C. Examples of oscillograms with peak voltage overshoot.
31 The text of this standard is based on the following documents:
FDIS Report on voting
32 Full information on the voting for the approval of this standard can be found in the report on voting
33 indicated in the above table.
34 This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
35 Annexes A, B and C are informative only.
IEC CD 60076-4  IEC:2020 – 4 –
37 IEC 60076 consists of the following parts, under the general title Power transformers:
38 Part 1: General
39 Part 2: Temperature rise
40 Part 3: Insulation levels, dielectric tests and external clearances in air
41 Part 4: Lightning impulse and Switching impulse Tests – Power Transformers and Reactors
42 Part 5: Ability to withstand short-circuit
43 Part 8: Application guide
44 Part 10: Determination of sound levels
45 Part xx: to be update by TC14 secretary
46 The committee has decided that the contents of this publication will remain unchanged until 20xx. At this
47 date, the publication will be
48 • reconfirmed;
49 • withdrawn;
50 • replaced by a revised edition, or
51 • amended.
IEC CD 60076-4  IEC:2020 – 5 –
54 POWER TRANSFORMERS
56 Part 4: Lightning impulse and Switching impulse Tests
57 Power Transformers and Reactors
62 1 Scope
63 This part of IEC 60076 gives guidance and explanatory comments on the existing procedures for lightning
64 and switching impulse tests of power transformers to supplement the requirements of IEC 60076-3. It is
65 also generally applicable to the testing of reactors (see IEC 60076-6), modifications to power transformer
66 procedures being indicated where required.
67 Information is given on waveforms, test circuits including test connections, earthing practices, failure
68 detection methods, test procedures, measuring techniques and interpretation of results.
69 Where applicable, the test techniques are as recommended in IEC 60060-1 and IEC 60060-2.
70 2 Normative references
71 The following documents are referred to in the text in such a way that some or all of their content
72 constitutes requirements of this document. For dated references, only the edition cited applies. For
73 undated references, the latest edition of the referenced document (including any amendments) applies.
75 IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
76 IEC 60060-2, High-voltage test techniques – Part 2: Measuring systems
77 IEC 60076-3, Power transformers – Part 3: Insulation levels, dielectric tests and external clearances in
78 air
79 IEC 60076-6, Reactors
80 IEC 61083-1, Instruments and software used for measurement in high-voltage impulse tests – Part 1:
81 Requirements for instruments
82 IEC 61083-2, Digital recorders for measurements in high-voltage impulse tests – Part 2: Evaluation of
83 software used for the determination of the parameters of impulse waveforms
TM
84 IEEE Std C57.98 -2011, IEEE Guide for Transformer Impulse Tests
TM
85 IEEE Std 4 -2013, IEEE Standard for High-Voltage Testing Techniques
IEC CD 60076-4  IEC:2020 – 6 –
88 3 General
89 This standard is primarily based on the use of conventional impulse generators for both lightning and
90 switching impulse tests of transformers and reactors. The practice of switching impulse generation with
91 discharge of a separate capacitor into an intermediate or low-voltage winding is also applicable.
92 However, the method which employs an additional inductance in series with the capacitor to provide
93 slightly damped oscillations transferred into the high-voltage winding is not applicable.
94 Alternative means of switching impulse generation or simulation such as d.c. current interruption on an
95 intermediate or low-voltage winding or the application of a part-period of power frequency voltage are
96 not discussed since these methods are not as generally applicable.
97 Different considerations in the choice of test circuits (terminal connections) for lightning and switching
98 impulse tests apply for transformers and reactors. On transformers, all terminals and windings can be
99 lightning impulse tested to specific and independent levels. In switching impulse test, however, because
100 of the induced voltage transferred, a specified test level may only be obtained on one winding (see IEC
101 60076-3).
102 Whilst, on reactors, lightning impulse tests is similar to that on transformers, i.e., all terminals can be
103 tested separately, different considerations apply and different problems arise in switching impulse tests.
104 Hence, in this standard, lightning impulse tests are covered by a common text for both transformers
105 and reactors whilst switching impulse test is dealt with separately for the two types of equipment.
106 4 Specified waveforms
107 The voltage waveforms to be used normally during lightning and switching impulse tests of
108 transformers and reactors are given in IEC 60076-3, IEC 60076-6 and the methods for their
109 determination are given in IEC 60060-1.
110 5 Test circuit
111 The physical arrangement of test equipment, test object and measuring circuits can be divided into
112 three major circuits:
113 – the main circuit including the impulse generator, additional waveshaping components and the test
114 object;
115 – the voltage measuring circuit;
116 – the chopping circuit where applicable.
117 This basic arrangement is shown in Figure 1.
118 The following parameters influence the impulse waveform;
119 a) the effective capacitance C , and inductance of the test object, L ; C is constant for any given design
t t t
120 and any given waveform, L is also a constant for any given design. The effective L , however, may
t t
121 be influenced by the terminal treatment. It varies between the leakage inductance L for short-
s
122 circuited terminals and L for open-circuited terminals. More details in this respect are given in 7.1
o
123 and 7.3 and in annex A;
124 b) the generator capacitance C ;
g
125 c) waveshaping components, both internal and external to the generator, R , R , R , C (plus, where
si se p L
126 applicable, the impedance of a voltage divider Z );
127 d) the stray inductance and capacitance of the generator and the complete test circuit;
128 e) chopping equipment, where applicable.

IEC CD 60076-4  IEC:2020 – 7 –
129 f) Non-linear elements in the transformer, which can cause differences between impulses at different
130 voltage levels
131 The front time T is determined mainly by combination of the effective surge capacitance of the test
132 object, including C , and the generator internal and external series resistances.
L
133 The time to half-value T is, for lightning impulses, primarily determined by the generator capacitance,
134 the inductance of the test object and the generator discharge resistance or any other parallel resistance.
135 However, there are cases, for example, windings of extremely low inductance, where the series
136 resistance will have a significant effect also on the wavetail. For switching impulses, other parameters
137 apply; these are dealt with in clause 8.
138 The test equipment used in lightning and switching impulse applications is basically the same.
139 Differences are in details only, such as values of resistors and capacitors (and the terminal connections
140 of the test object).
141 To meet the different requirements of the waveform for lightning and switching impulses, due
142 consideration has to be given to the selection of the impulse generator parameters, such as capacitance
143 and series and discharge (parallel) resistances. For switching impulses, large values of series resistors
144 and/or load capacitors may be necessary, which will result in significant reduction of the efficiency.
145 While the output voltage of the impulse generator is determined by the test levels of the windings with
146 respect to their highest voltage for equipment U for the test object, the required energy storage
m
147 capability is essentially dependent on the inherent impedances of the test objec
...