IEC 60137:2008

IEC 60137
Edition 6.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Insulated bushings for alternating voltages above 1 000 V

Traversées isolées pour tensions alternatives supérieures à 1 000 V

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IEC 60137
Edition 6.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Insulated bushings for alternating voltages above 1 000 V

Traversées isolées pour tensions alternatives supérieures à 1 000 V

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XA
CODE PRIX
ICS 29.080.20 ISBN 2-8318-9916-8
– 2 – 60137 © IEC:2008
CONTENTS
FOREWORD.6
INTRODUCTION.8
1 Scope.9
2 Normative references .9
3 Terms and definitions .10
4 Ratings.16
4.1 Standard values of highest voltage for equipment (U ).16
m
4.2 Standard values of rated current (I ).16
r
4.3 Standard values of rated thermal short-time current (I ).16
th
4.4 Standard values of rated dynamic current (I ) .17
d
4.5 Minimum withstand values of cantilever load .17
4.6 Angle of mounting .18
4.7 Minimum nominal creepage distance .18
4.8 Temperature limits and temperature rise .18
4.9 Standard insulation levels .20
4.10 Test tap on transformer bushings .22
5 Operating conditions .22
5.1 Temporary overvoltages .22
5.2 Altitude.22
5.3 Temperature of ambient air and immersion media .23
5.4 Seismic conditions .24
6 Ordering information and markings .24
6.1 Enumeration of characteristics .24
6.1.1 Application .24
6.1.2 Classification of bushings .24
6.1.3 Ratings.24
6.1.4 Operating conditions.24
6.1.5 Design.25
6.2 Markings .26
7 Test requirements .27
7.1 General requirements.27
7.2 Test classification.27
7.2.1 Type tests .28
7.2.2 Routine tests .29
7.2.3 Special tests.29
7.3 Condition of bushings during dielectric and thermal tests .29
8 Type tests .31
8.1 Dry or wet power-frequency voltage withstand test .31
8.1.1 Applicability .31
8.1.2 Test method and requirements .31
8.1.3 Acceptance .31
8.2 Long duration power-frequency voltage withstand test (ACLD) .32
8.2.1 Applicability .32
8.2.2 Test method and requirements .32
8.2.3 Acceptance .32
8.3 Dry lightning impulse voltage withstand test (BIL).33

60137 © IEC:2008 – 3 –
8.3.1 Applicability .33
8.3.2 Test method and requirements .33
8.3.3 Acceptance .33
8.4 Dry or wet switching impulse voltage withstand test (SIL).34
8.4.1 Applicability .34
8.4.2 Test method and requirements .34
8.4.3 Acceptance .34
8.5 Thermal stability test .35
8.5.1 Applicability .35
8.5.2 Test method and requirements .35
8.5.3 Acceptance .36
8.6 Electromagnetic compatibility tests (EMC).36
8.6.1 Emission test.36
8.6.2 Immunity test.37
8.7 Temperature rise test .37
8.7.1 Applicability .37
8.7.2 Test method and requirements .37
8.7.3 Acceptance .39
8.8 Verification of thermal short-time current withstand .39
8.8.1 Applicability .39
8.8.2 Verification method and requirements.39
8.8.3 Acceptance .40
8.9 Cantilever load withstand test.41
8.9.1 Applicability .41
8.9.2 Test method and requirements .41
8.9.3 Acceptance .41
8.10 Tightness test on liquid-filled, compound-filled and liquid-insulated bushings .41
8.10.1 Applicability .41
8.10.2 Test method and requirements .42
8.10.3 Acceptance .42
8.11 Internal pressure test on gas-filled, gas-insulated and gas-impregnated
bushings .42
8.11.1 Applicability .42
8.11.2 Test method and requirements .42
8.11.3 Acceptance .42
8.12 External pressure test on partly or completely gas-immersed bushings .42
8.12.1 Applicability .42
8.12.2 Test method and requirements .42
8.12.3 Acceptance .43
8.13 Verification of dimensions .43
8.13.1 Applicability .43
8.13.2 Acceptance .43
9 Routine tests .43
9.1 Measurement of dielectric dissipation factor (tan δ) and capacitance at

ambient temperature .43
9.1.1 Applicability .43
9.1.2 Test method and requirements .43
9.1.3 Acceptance .43
9.2 Dry lightning impulse voltage withstand test (BIL).44

– 4 – 60137 © IEC:2008
9.2.1 Applicability .44
9.2.2 Test method and requirements .44
9.2.3 Acceptance .44
9.3 Dry power-frequency voltage withstand test .44
9.3.1 Applicability .44
9.3.2 Test method and requirements .45
9.3.3 Acceptance .45
9.4 Measurement of partial discharge quantity .45
9.4.1 Applicability .45
9.4.2 Test method and requirements .45
9.4.3 Acceptance .45
9.5 Tests of tap insulation .46
9.5.1 Applicability and test requirements .46
9.5.2 Acceptance .46
9.6 Internal pressure test on gas-filled, gas-insulated and gas-impregnated
bushings .46
9.6.1 Applicability .46
9.6.2 Test method and requirements .47
9.6.3 Acceptance .47
9.7 Tightness test on liquid-filled, compound-filled and liquid-insulated bushings .47
9.7.1 Applicability .47
9.7.2 Test method and requirements .47
9.7.3 Acceptance .47
9.8 Tightness test on gas-filled, gas-insulated and gas-impregnated bushings .47
9.8.1 Applicability .47
9.8.2 Test method and requirements .47
9.8.3 Acceptance .48
9.9 Tightness test at the flange or other fixing device.48
9.9.1 Applicability .48
9.9.2 Test method and requirements .48
9.9.3 Acceptance .48
9.10 Visual inspection and dimensional check.49
9.10.1 Applicability .49
9.10.2 Acceptance .49
10 Requirements and tests for bushings of highest voltages for equipment equal to or
less than 52 kV made of ceramic, glass or inorganic materials, resin or combined
insulation.49
10.1 Temperature requirements .49
10.2 Level of immersion medium .49
10.3 Markings .49
10.4 Test requirements .50
10.4.1 Type tests .50
10.4.2 Routine tests .50
11 Recommendations for transport, storage, erection, operation and maintenance.51
11.1 Conditions during transport, storage and installation .51
11.2 Installation .51
11.3 Unpacking and lifting.51
11.4 Assembly .52
11.4.1 Mounting .52

60137 © IEC:2008 – 5 –
11.4.2 Connections .52
11.4.3 Final installation inspection.52
11.5 Operation .53
11.6 Maintenance.53
11.6.1 General .53
11.6.2 Recommendation for the manufacturer .53
11.6.3 Recommendations for the user .53
11.6.4 Failure report.54
12 Safety.55
12.1 Electrical aspects .55
12.2 Mechanical aspects.55
12.3 Thermal aspects.55
13 Environmental aspects .55
Bibliography.57

Figure 1 – Altitude correction factor .23
Figure 2 – Marking plate for bushings for highest voltage for equipment greater than
100 kV (see 6.2) .26
Figure 3 – Marking plate for bushings for highest voltage for equipment equal to or
less than 100 kV, except for bushings for which Figure 2 is applicable (see 6.2).27
Figure 4 – Marking plate for bushings for highest voltage for equipment equal to or
less than 52 kV made of ceramic, glass or inorganic materials, resin or combined
insulation (see 10.3) .27
Figure 5 – Voltage profile for long duration test ACLD .32

Table 1 – Minimum values of cantilever withstand load (see 4.5 and 8.9).17
Table 2 – Maximum values of temperature and temperature rise above ambient air
(see 4.8) .19
Table 3 – Temperature of ambient air and immersion media (see 5.3) .20
Table 4 – Insulation levels for highest voltage for equipment (see 4.9, 8.1, 8.3, 8.4, 9.2
and 9.3) .21
Table 5 – Applicability of type tests (see 7.2.1, excluding bushings according to
Clause 10) .28
Table 6 – Applicability of routine tests (see 7.2.2, excluding bushings according to
Clause 10) .29
Table 7 – Correction of test voltages (see 7.3).31
Table 8 – Maximum values of tan δ and tan δ increase (see 9.1) .44
Table 9 – Maximum values of partial discharge quantity (see 8.2 and 9.4) .46
Table 10 – Applicability of type tests for bushings according to Clause 10 (see 10.4.1) .50
Table 11 – Applicability of routine tests for bushings according to Clause 10 (see
10.4.2) .51

– 6 – 60137 © IEC:2008
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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
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
interested IEC National Committees.
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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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
International Standard IEC 60137 has been prepared by sub-committee 36A: Insulated
bushings, of IEC technical committee 36: Insulators.
This sixth edition cancels and replaces the fifth edition, published in 2003, and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• Long duration power-frequency for transformer bushings.
• Special requirements for type and acceptance tests applicable to transformer and GIS
bushings.
• Specific insulation levels for bushings fitted to transformers and GIS.
• According to IEC Guide 111, clauses relating to safety and the environment have been
added.
• The altitude correction procedure has been revised ( > 1 000 m).

60137 © IEC:2008 – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
36A/134/FDIS 36A/135/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – 60137 © IEC:2008
INTRODUCTION
In the preparation of this standard further consideration has been given to the test
requirements for power transformers as described in IEC 60076-3:2000. 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.
60137 © IEC:2008 – 9 –
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 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.
IEC 60038:1983, IEC standard voltages
Amendment 2 (1997)
IEC 60050(212):1990, International Electrotechnical Vocabulary – Part 212: 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: 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 transformers

– 10 – 60137 © IEC:2008
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 60376, Specification of technical grade sulfur hexafluoride (SF6) for use in electrical
equipment
IEC 60480, Guidelines for the checking and treatment of sulphur hexafluoride (SF6) 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 61462, Composite insulators – Hollow insulators for use in outdoor and indoor electrical
equipment – Definitions, test methods, acceptance criteria and design recommendations
IEC 61463, Bushings – Seismic qualification
IEC 62155, Hollow pressurised and unpressurised ceramic and glass insulators for use in
electrical equipment with rated voltages greater than 1 000 V
IEC 62217, Polymeric 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
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.
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
[IEV 471-02-01]
NOTE 1 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.

60137 © IEC:2008 – 11 –
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 oil
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 oil or another insulating liquid
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 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 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 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 3.13).
NOTE 3 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 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, the space between the core and the insulating envelope being filled with
the same gas
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 oil
NOTE 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 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.

– 12 – 60137 © IEC:2008
NOTE 2 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 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
ceramic, glass or analogous inorganic material bushing
bushing in which the major insulation consists of a ceramic, glass or analogous inorganic
material
3.12
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
3.13
combined insulation bushing
bushing in which the major insulation consists of a combination of at least two different
insulating materials
3.14
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
[IEV 471-02-03]
3.15
indoor bushing
bushing, both ends of which are intended to be in ambient air at atmospheric pressure, but
not exposed to outdoor atmospheric conditions
[IEV 471-02-05]
3.16
outdoor bushing
bushing, both ends of which are intended to be in ambient air at atmospheric pressure and
exposed to outdoor atmospheric conditions
[IEV 471-02-07]
3.17
outdoor-indoor bushing
bushing, both ends of which are intended to be in ambient air at atmospheric pressure. One
end is intended to be exposed to outdoor atmospheric conditions, and the other end not to be
exposed to outdoor atmospheric conditions
[IEV 471-02-09]
3.18
indoor-immersed bushing
bushing, one end of which is intended to be in ambient air but not exposed to outdoor
atmospheric conditions and the other end to be immersed in an insulating medium other than
ambient air (e.g. oil or gas)
60137 © IEC:2008 – 13 –
[IEV 471-02-06]
NOTE This definition includes bushings operating in air at temperatures above ambient, such as occur with air-
insulated ducting.
3.19
outdoor-immersed bushing
bushing, one end of which is intended to be in ambient air and exposed to outdoor
atmospheric conditions and the other end to be immersed in an insulating medium other than
ambient air (e.g. oil or gas)
[IEV 471-02-08]
3.20
completely immersed bushing
bushing, both ends of which are intended to be immersed in an insulating medium other than
ambient air (e.g. oil or gas)
[IEV 471-02-04]
3.21
plug-in type bushing
bushing for separable connector
bushing, one end of which is immersed in an insulating medium and the other end designed to
receive a separable insulated cable connector, without which the bushing cannot function
[IEV 471-02-02]
3.22
highest voltage for equipment
U
m
highest r.m.s. value of phase-to-phase voltage for which the equipment is designed in respect
of its insulation as well as other characteristics which relate to this voltage in the relevant
equipment standard
[IEV 604-03-01]
3.23
rated phase-to-earth voltage
maximum r.m.s. value of the voltage which the bushing withstands continuously between the
conductor and the earthed flange or other fixing device, under the operating conditions
specified in Clause 5
3.24
rated current
I
r
maximum r.m.s. value of current which the bushing can carry continuously under the
operating conditions specified in Clause 5, without exceeding the temperature rise limits
of Table 2
3.25
rated thermal short-time current
I
th
r.m.s. value of a symmetrical current which the bushing withstands thermally for the rated
duration (t ) immediately following continuous operation at rated current with maximum
th
temperatures of ambient air and immersion media in accordance with 5.3

– 14 – 60137 © IEC:2008
3.26
rated dynamic current
I
d
peak value of a current which the bushing withstands mechanically
3.27
temperature rise
difference between the measured temperature of the hottest spot of the metal parts of the
bushing which are in contact with insulating material and the ambient air temperature (see 4.8)
3.28
rated frequency
f
r
frequency at which the bushing is designed to operate
[IEV 421-04-03, modified]
3.29
rated filling pressure of gas for insulation
the pressure in Pascal (Pa) for insulation referred to the standard atmospheric conditions of
+20 ºC and 101,3 kPa (or density), which may be expressed in relative or absolute terms, to
which the bushing is filled before being put into service, or automatically replenished
3.30
maximum internal operating gas pressure
pressure, when the bushing is in operation, carrying rated current at the highest temperatures
in accordance with 5.3
3.31
maximum external operating gas pressure
maximum pressure of the gaseous insulating medium in which the bushing is partially or
completely immersed when in operation
3.32
design pressure (of the enclosure)
pressure used to determine the thickness of the enclosure
(see IEC 62271-203:2003, Definition 3.113, modified)
3.33
leak rate (of gas-filled, gas-insulated, gas-impregnated and gas-immersed bus
...