IEC 60137:2017

IEC 60137 ®
Edition 7.0 2017-06
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulated bushings for alternating voltages above 1 000 V

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IEC 60137 ®
Edition 7.0 2017-06
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulated bushings for alternating voltages above 1 000 V

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.20 ISBN 978-2-8322-4517-0

– 2 – IEC 60137:2017 RLV  IEC 2017
CONTENTS
FOREWORD . 7
INTRODUCTION . 2
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 12
4 Ratings . 18
4.1 Standard values of Rated highest voltage for equipment (U ) . 18
m
4.2 Standard values of Rated current (I ) . 18
r
4.3 Standard values of Rated thermal short-time current (I ) . 18
th
4.4 Standard values of Rated dynamic current (I ) . 19
d
4.5 Minimum withstand values of cantilever load . 19
4.6 Angle of mounting . 20
4.7 Minimum nominal creepage distance . 20
4.8 Temperature limits and temperature rise . 21
4.9 Insulation levels . 21
4.10 Test tap on transformer bushings . 24
5 Operating conditions . 25
5.1 Temporary overvoltages. 25
5.2 Altitude . 25
5.3 Temperature of ambient air and immersion media . 27
5.4 Seismic conditions . 28
5.5 Very fast transients (VFT) . 28
5.6 Transformer insulating liquid . 29
6 Ordering information and markings . 29
6.1 Enumeration of characteristics . 29
6.1.1 General . 29
6.1.2 Application . 29
6.1.3 Classification of bushings . 29
6.1.4 Ratings . 29
6.1.5 Operating conditions . 29
6.1.6 Design . 30
6.2 Markings . 31
7 Test requirements . 32
7.1 General requirements . 33
7.2 Test classification . 33
7.2.1 General . 33
7.2.2 Type tests . 33
7.2.3 Routine tests . 34
7.2.4 Special tests . 35
7.3 Condition of bushings during dielectric and thermal tests . 35
8 Type tests . 2
8.1 General . 37
8.2 Dry or wet power-frequency voltage withstand test . 37
8.2.1 Applicability . 37
8.2.2 Test method and requirements . 37

8.2.3 Acceptance . 37
8.3 Long duration power-frequency voltage withstand test (ACLD) . 37
8.3.1 Applicability . 37
8.3.2 Test method and requirements . 37
8.3.3 Acceptance . 38
8.4 Dry lightning impulse voltage withstand test (BIL) . 38
8.4.1 Applicability . 38
8.4.2 Test method and requirements . 38
8.4.3 Acceptance . 39
8.5 Dry or wet switching impulse voltage withstand test (SIL) . 39
8.5.1 Applicability . 39
8.5.2 Test method and requirements . 39
8.5.3 Acceptance . 40
8.6 Thermal stability test . 41
8.6.1 Applicability . 41
8.6.2 Test method and requirements . 41
8.6.3 Acceptance . 41
8.7 Electromagnetic compatibility tests (EMC) . 42
8.7.1 Emission test . 42
8.7.2 Immunity test . 43
8.8 Temperature rise test . 43
8.8.1 Applicability . 43
8.8.2 Test method and requirements . 43
8.8.3 Acceptance . 44
8.9 Verification of thermal short-time current withstand . 44
8.9.1 Applicability . 44
8.9.2 Verification method and requirements . 44
8.9.3 Acceptance . 45
8.10 Cantilever load withstand test . 46
8.10.1 Applicability . 46
8.10.2 Test method and requirements . 46
8.10.3 Acceptance . 46
8.11 Tightness test on liquid-filled, compound-filled and liquid-insulated bushings . 47
8.11.1 Applicability . 47
8.11.2 Test method and requirements . 47
8.11.3 Acceptance . 47
8.12 Internal pressure test on gas-filled, gas-insulated and gas-impregnated
bushings . 47
8.12.1 Applicability . 47
8.12.2 Test method and requirements . 47
8.12.3 Acceptance . 47
8.13 External pressure test on partly or completely gas-immersed bushings . 47
8.13.1 Applicability . 47
8.13.2 Test method and requirements . 48
8.13.3 Acceptance . 48
8.14 Verification of dimensions . 48
8.14.1 Applicability . 48
8.14.2 Acceptance . 48
9 Routine tests . 48

– 4 – IEC 60137:2017 RLV  IEC 2017
9.1 General . 48
9.2 Measurement of dielectric dissipation factor (tan δ) and capacitance at
ambient temperature . 48
9.2.1 Applicability . 48
9.2.2 Test method and requirements . 48
9.2.3 Acceptance . 49
9.3 Dry lightning impulse voltage withstand test (BIL) . 49
9.3.1 Applicability . 49
9.3.2 Test method and requirements . 49
9.3.3 Acceptance . 50
9.4 Dry power-frequency voltage withstand test . 50
9.4.1 Applicability . 50
9.4.2 Test method and requirements . 50
9.4.3 Acceptance . 50
9.5 Measurement of partial discharge quantity . 50
9.5.1 Applicability . 50
9.5.2 Test method and requirements . 50
9.5.3 Acceptance . 51
9.6 Tests of tap insulation . 52
9.6.1 Applicability and test requirements . 52
9.6.2 Acceptance . 52
9.7 Internal pressure test on gas-filled, gas-insulated and gas-impregnated
bushings . 52
9.7.1 Applicability . 52
9.7.2 Test method and requirements . 52
9.7.3 Acceptance . 52
9.8 Tightness test on liquid-filled, compound-filled and liquid-insulated bushings . 52
9.8.1 Applicability . 52
9.8.2 Test method and requirements . 52
9.8.3 Acceptance . 53
9.9 Tightness test on gas-filled, gas-insulated and gas-impregnated bushings . 53
9.9.1 Applicability . 53
9.9.2 Test method and requirements . 53
9.9.3 Acceptance . 53
9.10 Tightness test at the flange or other fixing device . 53
9.10.1 Applicability . 53
9.10.2 Test method and requirements . 54
9.10.3 Acceptance . 54
9.11 Visual inspection and dimensional check . 54
9.11.1 Applicability . 54
9.11.2 Acceptance . 54
10 Requirements and tests for non-capacitance graded bushings of rated highest
voltages for equipment equal to or less than up to and including 52 kV made of
ceramic, glass or inorganic materials, resin or combined insulation . 55
10.1 General . 55
10.2 Temperature requirements . 55
10.3 Level of immersion medium. 55
10.4 Markings . 55
10.5 Test requirements . 55
10.5.1 General . 55

10.5.2 Type tests . 55
10.5.3 Routine tests . 56
11 Recommendations for transport, storage, erection, operation and maintenance . 56
11.1 General . 56
11.2 Conditions during transport, storage and installation . 57
11.3 Installation . 57
11.4 Unpacking and lifting . 57
11.5 Assembly . 57
11.5.1 General . 57
11.5.2 Mounting . 57
11.5.3 Connections . 58
11.5.4 Final installation inspection . 58
11.6 Operation . 58
11.7 Maintenance . 59
11.7.1 General . 59
11.7.2 Recommendation for the manufacturer . 59
11.7.3 Recommendations for the user . 59
11.7.4 Failure report . 60
12 Safety . 61
12.1 General . 61
12.2 Electrical aspects . 61
12.3 Mechanical aspects . 61
12.4 Thermal aspects . 61
13 Environmental aspects . 61
Annex A (informative) Determination of the hottest spot in bushings with conductors
embedded in the insulation material . 63
Bibliography . 64

Figure 1 – Altitude correction factor .
Figure 1 – Factor m on the co-ordination switching impulse withstand voltage . 26
Figure 2 – Marking plate for bushings for rated highest voltage for equipment (U )
m
greater than 100 kV . 32
Figure 3 – Marking plate for bushings for rated highest voltage for equipment (U )
m
equal to or less than 100 kV, except for bushings for which Figure 4 is applicable . 32
Figure 4 – Marking plate for bushings for rated highest voltage for equipment (U )
m
equal to or less than 52 kV made of ceramic, glass or inorganic materials, resin or
combined insulation (see 10.3) . 32
Figure 5 – Voltage profile for long duration test (ACLD) . 38

Table 1 – Minimum values of cantilever withstand load (see 4.5 and 8.10) . 20
Table 2 – Maximum values of temperature and temperature rise above ambient air
(see 4.8) . 22
Table 3 – Insulation levels for highest voltage for equipment (U ) (see 4.9, 8.2, 8.4,
m
8.5, 9.3 and 9.4) . 23
Table 4 – Temperature of ambient air and immersion media . 28
Table 5 – Applicability of type tests (see 7.2.2, excluding bushings according to
Clause 10) . 34

– 6 – IEC 60137:2017 RLV  IEC 2017
Table 6 – Applicability of routine tests (see 7.2.3, excluding bushings according to
Clause 10) . 35
Table 7 – Correction of test voltages (see 7.3) . 36
Table 8 – Maximum values of tan δ and tan δ increase (see 9.2) . 49
Table 9 – Maximum values of partial discharge quantity (see 8.3 and 9.5) . 51
Table 10 – Applicability of type tests for bushings according to Clause 10 (see 10.5.1). 56
Table 11 – Applicability of routine tests for bushings according to Clause 10
(see 10.5.3) . 56

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATED BUSHINGS FOR ALTERNATING
VOLTAGES ABOVE 1 000 V
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
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 8 – IEC 60137:2017 RLV © IEC 2017
International Standard IEC 60137 has been prepared by sub-committee 36A: Insulated
bushings, of IEC technical committee 36: Insulators.
This seventh edition cancels and replaces the sixth edition, published in 2008, and constitutes
a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• Resin-impregnated synthetic (RIS) bushings has been introduced.
• Bushings with U ≤ 1,1 kV, U = 1 100 kV and U = 1 200 kV have been introduced.
m m m
• Temperature rise testing has been included for liquid-insulated bushings according to
clause to 3.4.
• Introducing dry lightning impulse testing as a routine test for all transformer bushings with
U > 72,5 kV.
m
• The altitude correction procedure has been revised ( > 1 000 m).
• An explanation about Very Fast Transient (VFT) phenomenon and its impact on bushings
has been included.
The text of this International Standard is based on the following documents:
FDIS Report on voting
36A/187/FDIS 36A/189/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://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.
The contents of the corrigendum of May 2018 have been included in this copy.

IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

INTRODUCTION
In the preparation of the current edition of this standard further consideration has been given
to the test requirements for power transformers as described in IEC 60076-3:2000 2013.
Extensions have been made to the requirements for lightning impulse type testing and an
additional test - long duration power-frequency withstand test - has been included.
In anticipation of changes in the creepage correction factors defined in IEC 60815 and
currently under review by TC 36, details of the correction method have been removed from
this standard.
– 10 – IEC 60137:2017 RLV  IEC 2017
INSULATED BUSHINGS FOR ALTERNATING
VOLTAGES ABOVE 1 000 V
1 Scope
This International Standard specifies the characteristics and tests for insulated bushings.
This standard is applicable to bushings, as defined in Clause 3, intended for use in electrical
apparatus, machinery, transformers, switchgear and installations for three-phase alternating
current systems, having highest voltage for equipment above 1 000 V and power frequencies
of 15 Hz up to and including 60 Hz.
Subject to special agreement between purchaser and supplier, this standard may be applied,
in part or as a whole, to the following:
• bushings used in other than three-phase systems;
• bushings for high-voltage direct current systems;
• bushings for testing transformers;
• bushings for capacitors.
Special requirements and tests for transformer bushings in this standard apply also to reactor
bushings.
This standard is applicable to bushings made and sold separately. Bushings which are a part
of an apparatus and which cannot be tested according to this standard should be tested with
the apparatus of which they form part.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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.
IEC 60038:1983, IEC standard voltages
Amendment 2 (1997)
IEC 60050-212:1990 2010, International Electrotechnical Vocabulary – Part 212: Electrical
insulating solids, liquids and gases
IEC 60059, IEC standard current ratings
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60068-2-17:1994, Basic environmental testing procedures – Part 2-17: Tests – Test Q:
Sealing
IEC 60071-1, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60076-5, Power transformers – Part 5: Ability to withstand short circuit

IEC 60076-7, Power transformers – Part 7: Loading guide for oil-immersed power
transformers
IEC 60216-2, Electrical insulating materials – Thermal endurance properties – Part 2:
Determination of thermal endurance properties of electrical insulating materials – Choice of
test criteria
IEC 60270, High-voltage test techniques – Partial discharge measurements
IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for
transformers and switchgear
IEC 60376, Specification of technical grade sulfur hexafluoride (SF ) for use in electrical
equipment
IEC 60422, Mineral insulating oils in electrical equipment – Supervision and maintenance
guidance
IEC 60480, Guidelines for the checking and treatment of sulfur hexafluoride (SF ) taken from
electrical equipment and specification for its re-use
IEC 60505, Evaluation and qualification of electrical insulation systems
IEC 60815, Guide for the selection of insulators in respect of polluted conditions
IEC TS 60815-1, Selection and dimensioning of high-voltage insulators intended for use in
polluted conditions – Part 1: Definitions, information and general principles
IEC TS 60815-2, Selection and dimensioning of high-voltage insulators intended for use in
polluted conditions – Part 2: Ceramic and glass insulators for a.c. systems
IEC TS 60815-3, Selection and dimensioning of high-voltage insulators intended for use in
polluted conditions – Part 3: Polymer insulators for a.c. systems
IEC 61099, Insulating liquids – Specifications for unused synthetic organic esters for electrical
purposes
IEC 61462, Composite hollow insulators – Hollow Pressurized and unpressurized insulators
for use in outdoor and indoor electrical equipment with rated voltage greater than 1 000 V –
Definitions, test methods, acceptance criteria and design recommendations
IEC TS 61463, Bushings – Seismic qualification
IEC 62155:2003, Hollow pressurized and unpressurized ceramic and glass insulators for use
in electrical equipment with rated voltages greater than 1 000 V
IEC 62217, Polymeric HV insulators for indoor and outdoor use with nominal voltage greater
than 1 000 V – General definitions, test methods and acceptance criteria
IEC 62271 (all parts), High-voltage switchgear and controlgear
IEC 62271-1, High-voltage switchgear and controlgear – Part 1: Common specifications
IEC Guide 109, Environmental aspects – Inclusion in electrotechnical product standards

– 12 – IEC 60137:2017 RLV  IEC 2017
IEC Guide 111, Electrical high-voltage equipment in high-voltage substations – Common
recommendations for product standards
CISPR 16-1 (all parts), Specification for radio disturbance and immunity measuring apparatus
and methods
CISPR 18-2, Radio interference characteristics of overhead power lines and high-voltage
equipment – Parts 2: Methods of measurement and procedure for determining limits
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
bushing
device that enables one or several conductors to pass through a partition such as a wall or a
tank, and insulates the conductors from it; the means of attachment (flange or fixing device) to
the partition forms part of the bushing
Note 1 to entry: The conductor may form an integral part of the bushing or be drawn into the central tube of the
bushing.
NOTE 2 The bushing may be of the types as described in 3.2 to 3.21.
[SOURCE: IEC 60050-471:2007, 471-02-01]
3.2
liquid-filled bushing
bushing in which the space between the inside surface of the insulating envelope and the
solid major insulation is filled with mineral oil or other insulating liquid
3.3
compound-filled bushing
bushing in which the space between the inside surface of the insulating envelope and the
solid major insulation is filled with an insulating compound
3.4
liquid-insulated bushing
bushing in which the major insulation consists of mineral oil or another insulating liquid,
enclosed by an insulating envelope
Note 1 to entry: These bushings are often of an open design which require proper processing after installation in
order to avoid trapped air and subsequent partial discharges during testing or in service.
3.5
gas-filled bushing
bushing in which the space between the inside surface of the insulating envelope and the
solid major insulation is filled with gas (other than ambient air) at atmospheric pressure or
higher
Note 1 to entry: This definition includes bushings which are intended to form an integral part of gas-insulated
equipment, the gas of the equipment being in communication with that of the bushing.

3.6
gas-insulated bushing
bushing in which the major insulation consists of gas (other than ambient air) at atmospheric
pressure or higher
Note 1 to entry: This definition includes bushings which are intended to form an integral part of gas-insulated
equipment, the gas of the equipment being in communication with that of the bushing.
Note 2 to entry: A bushing which contains solid insulating materials other than the envelope containing the gas
(e.g. support for conducting layers or insulating cylinder), is a combined insulation bushing (see 3.14).
Note 3 to entry: A bushing in which the desired voltage grading is obtained by an arrangement of conducting or
semi-conducting layers incorporated in an insulating material (e.g. plastic film) is referred to as a gas insulated
condenser capacitance graded bushing.
3.7
gas-impregnated bushing
bushing in which the major insulation consists of a core wound from paper or plastic film (GIF)
and subsequently treated and impregnated with gas (other than ambient air) at atmospheric
pressure or higher
Note 1 to entry: the core is contained in an insulating envelope. The space between the core and the insulating
envelope being filled with the same gas as used for the impregnation.
3.8
oil-impregnated paper bushing
OIP
bushing in which the major insulation consists of a core wound from paper and subsequently
treated and impregnated with an insulating liquid, generally transformer mineral oil
Note 1 to entry: The core is contained in an insulating envelope, the space between the core and the insulating
envelope being filled with the same insulating liquid as that used for impregnation.
3.9
resin-bonded paper bushing
RBP
bushing in which the major insulation consists of a core wound from resin-coated paper
Note 1 to entry: During the winding process, each paper layer is bonded to the previous layer by its resin coating
and the bonding achieved by curing the resin.
Note 2 to entry: A resin-bonded paper bushing can be provided with an insulating envelope, in which case the
intervening space can be filled with an insulating liquid or another insulating medium.
3.10
resin-impregnated paper bushing
RIP
bushing in which the major insulation consists of a core wound from untreated paper and
subsequently impregnated with a curable resin
Note 1 to entry: A resin-impregnated paper bushing can be provided with an insulating envelope, in which case
the intervening space can be filled with an insulating liquid or another insulating medium.
3.11
resin-impregnated synthetics bushing
RIS
bushing in which the major insulation consists of a core wound from synthetics subsequently
impregnated with a curable resin
Note 1 to entry: A resin-impregnated synthetics bushing can be provided with an insulating envelope, in which
case the intervening space can be filled with an insulating liquid or another insulating medium.
Note 2 to entry: If not otherwise stated by the manufacturer, bushings in accordance with 3.11 shall be
considered as RIP bushings according 3.10.

– 14 – IEC 60137:2017 RLV  IEC 2017
3.12
ceramic, glass or analogous inorganic material bushing
bushing in which the major insulation consists of a ceramic, glass or analogous inorganic
material
3.13
cast or moulded resin-insulated bushing
bushing in which the major insulation consists of a cast or moulded organic material with or
without an inorganic filler
3.14
combined insulation bushing
bushing in which the major insulation consists of a combination of at least two different
insulating materials
3.15
capacitance graded bushing
bushing, in which a desired voltage grading is obtained by an arrangement of conducting or
semiconducting layers incorporated into the insulating material
[SOURCE: IEC 60050-471:2007, 471-02-03]
3.16
indoor bushing
bushing, both ends of which are intended to be in ambient air at atmospheric pressure, but
not exposed to outdoor atmospheric conditions
[SOURCE: IEC 60050-471:2007, 471-02-05]
3.17
outdoor bushing
bushing, both ends o
...