EN ISO/IEC 17050-2:2004

SLOVENSKI STANDARD
01-marec-2012
=ROMHPSROQMHQDHOHNWULþQDRSUHPD9]RUþHQMHSOLQRYLQDQDOL]LUDQMHSURVWLKLQ
UD]WRSOMHQLKSOLQRY1DSRWHN
Oil-filled electrical equipment - Sampling of gases and analysis of free and dissolved
gases - Guidance
Ölgefüllte elektrische Betriebsmittel - Probennahme von Gasen und die Analyse freier
und gelöster Gase - Anleitung
Matériels électriques immergés - Echantillonnage de gaz et analyse des gaz libres et
dissous - Lignes directrices
Ta slovenski standard je istoveten z: EN 60567:2011
ICS:
29.040.10 Izolacijska olja Insulating oils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 60567
NORME EUROPÉENNE
December 2011
EUROPÄISCHE NORM
ICS 29.040 Supersedes EN 60567:2005

English version
Oil-filled electrical equipment -
Sampling of gases and analysis of free and dissolved gases -
Guidance
(IEC 60567:2011)
Matériels électriques immergés -  Ölgefüllte elektrische Betriebsmittel –
Echantillonnage de gaz et analyse des Probennahme von Gasen und Analyse
gaz libres et dissous - freier und gelöster Gase – Anleitung
Lignes directrices (IEC 60567:2011)
(CEI 60567:2011)
This European Standard was approved by CENELEC on 2011-11-24. 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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, 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

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60567:2011 E
EN 60567:2011 - 2 -
Foreword
The text of document 10/849/FDIS, future edition 4 of IEC 60567, prepared by IEC/TC 10 "Fluids for
electrotechnical applications" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN 60567:2011.
The following dates are fixed:
(dop) 2012-08-24
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2014-11-24
• latest date by which the national
standards conflicting with the
document have to be withdrawn
This document supersedes EN 60567:2005.
EN 60567:2011 includes the following significant technical changes with respect to EN 60567:2005:
Since the publication of EN 60567:2005, CIGRE TF.D1.01.15 has made progress in several areas of
dissolved gas analysis (DGA), notably
a) oil sampling,
b) laboratory analysis and solubility coefficients of gases in non-mineral oils,
c) calibration of the headspace gas extraction method,
d) more sensitive detectors for chromatography,
e) preparation of air-saturated standards and
f) evaluation of gas monitor readings.
These advances are included in EN 60567:2011.
Sampling of oil for DGA from oil-filled equipment has been moved from EN 60567 to EN 60475 as
reflected in the revised title of this standard.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 60567:2011 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
[1] ISO/IEC 17025 NOTE  Harmonized as EN ISO/IEC 17025.
[2] ISO 3675 NOTE  Harmonized as EN ISO 3675.

- 3 - EN 60567:2011
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60296 - Fluids for electrotechnical applications - EN 60296 -
Unused mineral insulating oils for
transformers and switchgear
IEC 60475 2011 Method of sampling insulating liquids EN 60475 2011

IEC 60599 - Mineral oil-impregnated electrical equipment EN 60599 -
in service - Guide to the interpretation of
dissolved and free gases analysis

ISO 5725 Series Accuracy (trueness and precision) of - -
measurement methods and results

ASTM D2780 - Standard Test Method for Solubility of Fixed - -
Gases in Liquids
IEC 60567 ®
Edition 4.0 2011-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Oil-filled electrical equipment – Sampling of gases and analysis of free and
dissolved gases – Guidance
Matériels électriques immergés – Échantillonnage de gaz et analyse des gaz
libres et dissous – Lignes directrices

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XA
ICS 29.040 ISBN 978-2-88912-768-9

– 2 – 60567 © IEC:2011
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references . 9
3 Sampling of gases from gas-collecting (Buchholz) relays . 10
3.1 General remarks. 10
3.2 Sampling of free gases by syringe . 10
3.2.1 Sampling equipment . 10
3.2.2 Sampling procedure. 11
3.3 Sampling of free gases by displacement of oil . 12
3.4 Sampling of free gases by vacuum . 13
3.5 Sampling of oil from oil filled equipment . 14
4 Labelling of gas samples . 14
5 Sampling, labelling and transferring of oil from oil-filled equipment . 14
5.1 Sampling and labelling of oil . 14
5.2 Transfer of oil for DGA analysis . 14
5.2.1 Transfer from oil syringes . 14
5.2.2 Transfer from ampoules . 15
5.2.3 Transfer from flexible metal bottles . 15
5.2.4 Transfer from glass and rigid metal bottles . 15
6 Preparation of gas-in-oil standards . 15
6.1 General remark . 15
6.2 First method: preparation of a large volume of gas-in-oil standard . 15
6.2.1 Equipment . 15
6.2.2 Procedure . 16
6.2.3 Calculation . 18
6.3 Second method: preparation of gas-in-oil standards in a syringe or a vial . 18
6.3.1 Equipment . 19
6.3.2 Procedure . 20
7 Extraction of gases from oil . 20
7.1 General remarks. 20
7.2 Multi-cycle vacuum extraction using Toepler pump apparatus . 21
7.2.1 Toepler pump extraction apparatus . 21
7.2.2 Extraction procedure . 24
7.3 Vacuum extraction by partial degassing method . 25
7.3.1 General remark . 25
7.3.2 Partial degassing apparatus . 25
7.3.3 Extraction procedure . 26
7.4 Stripping extraction method . 26
7.4.1 Stripping apparatus . 26
7.4.2 Outline of procedure . 29
7.5 Headspace method . 30
7.5.1 Principle of the method . 30
7.5.2 Symbols and abbreviations . 30
7.5.3 Headspace extraction apparatus. 31
7.5.4 Headspace extraction procedure . 35

60567 © IEC:2011 – 3 –
7.5.5 Calibration of the headspace extractor . 39
8 Gas analysis by gas-solid chromatography . 41
8.1 General remarks. 41
8.2 Outline of suitable methods using Table 4 . 42
8.3 Apparatus . 42
8.3.1 Gas chromatograph . 42
8.3.2 Columns . 44
8.3.3 Carrier gas . 44
8.3.4 Detectors . 44
8.3.5 Methanator . 44
8.3.6 Cold trap . 44
8.3.7 Integrator and recorder . 44
8.4 Preparation of apparatus . 45
8.5 Analysis . 45
8.6 Calibration of the chromatograph . 45
8.7 Calculations . 46
9 Quality control . 46
9.1 Verification of the entire analytical system . 46
9.2 Limits of detection and quantification . 47
9.3 Repeatability, reproducibility and accuracy . 47
9.3.1 General remark . 47
9.3.2 Repeatability . 48
9.3.3 Reproducibility . 48
9.3.4 Accuracy . 48
10 Report of results . 49
Annex A (informative) Correction for incomplete gas extraction in partial degassing
method by calculation . 51
Annex B (informative) Mercury-free and shake test versions of the standard extraction
methods . 53
Annex C (informative) Preparation of air-saturated standards . 55
Annex D (informative) Correction for gas bubbles in syringes and air gap in rigid
bottles . 56
Annex E (informative) Procedure for comparing gas monitor readings to laboratory
results . 57
Bibliography . 58

Figure 1 – Sampling of gas by syringe . 11
Figure 2 – Sampling of free gases by oil displacement . 12
Figure 3 – Sampling of free gases by vacuum . 13
Figure 4 – First method of preparing gas-in-oil standards . 17
Figure 5 – Second method for preparing gas-in-oil standards . 19
Figure 6 – Example of a Toepler pump extraction apparatus . 23
Figure 7 – Types of glass strippers . 27
Figure 8 – Stainless steel stripper . 28
Figure 9 – Schematic arrangement for connecting an oil stripper to a gas
chromatograph . 29
Figure 10 – Schematic representation of headspace sampler . 30

– 4 – 60567 © IEC:2011
Figure 11 – Vial filled with water . 32
Figure 12 – Revolving table . 34
Figure 13 – Schematic arrangement for gas chromatography . 43
Figure B.1 – Schematic representation of methods in Annex B . 54

Table 1 – Information required for gas samples . 14
Table 2 – Examples of headspace operating conditions . 35
Table 3 – Headspace partition coefficients at 70 °C in mineral insulating oil . 40
Table 4 – Examples of gas chromatographic operating conditions . 41
Table 5 – Required limits of detection in oil . 47
Table 6 – Examples of accuracy of extraction methods . 49
Table A.1 – Examples of solubility coefficients a (at 25 ºC) reported by CIGRE TF
i
D1.01.15 . 51
Table C.1 – Examples of solubility values of air for different oil types . 55
Table C.2 – Examples of temperature variations for oxygen and nitrogen solubility in
mineral oil . 55

60567 © IEC:2011 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OIL-FILLED ELECTRICAL EQUIPMENT –
SAMPLING OF GASES AND ANALYSIS
OF FREE AND DISSOLVED GASES –
GUIDANCE
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,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 60567 has been prepared by IEC technical committee 10: Fluids
for electrotechnical applications.
This fourth edition cancels and replaces the third edition, published in 2005, and constitutes a
technical revision.
The main changes with respect to the previous edition are listed below:
Since the publication of the third edition, CIGRE TF.D1.01.15 has made progress in several
areas of dissolved gas analysis (DGA), notably
a) oil sampling,
b) laboratory analysis and solubility coefficients of gases in non-mineral oils,
c) calibration of the headspace gas extraction method,

– 6 – 60567 © IEC:2011
d) more sensitive detectors for chromatography,
e) preparation of air-saturated standards and
f) evaluation of gas monitor readings.
These advances are included in this fourth edition.
Sampling of oil for DGA from oil-filled equipment has been moved from IEC 60567 to
IEC 60475 as reflected in the revised title of this standard.
The text of this standard is based on the following documents:
FDIS Report on voting
10/849/FDIS 10/872/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 stability 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.
60567 © IEC:2011 – 7 –
INTRODUCTION
Gases may be formed in oil-filled electrical equipment due to natural ageing but also, to a
much greater extent, as a result of faults.
Operation with a fault may seriously damage the equipment, and it is valuable to be able to
detect the fault at an early stage of development.
Where a fault is not severe, the gases formed will normally dissolve in the oil, with a small
proportion eventually diffusing from the liquid into any gas phase above it. Extracting
dissolved gas from a sample of the oil and determining the amount and composition of this
gas is a means of detecting such faults, and the type and severity of any fault may often be
inferred from the composition of the gas and the rate at which it is formed.
In the case of a sufficiently severe fault, free gas will pass through the oil and collect in the
gas-collecting (Buchholz) relay if fitted; if necessary, this gas may be analysed to assist in
determining the type of fault that has generated it. The composition of gases within the
bubbles changes as they move through the oil towards the gas-collecting relay.
This can be put to good use, as information on the rate of gas production may often be
inferred by comparing the composition of the free gases collected with the concentrations
remaining dissolved in the liquid.
The interpretation of the gas analyses is the subject of IEC 60599.
These techniques are valuable at all stages in the life of oil-filled equipment. During
acceptance tests on transformers in the factory, comparison of gas-in-oil analyses before,
during and after a heat run test can show if any hot-spots are present, and similarly analysis
after dielectric testing can add to information regarding the presence of partial discharges or
sparking. During operation in the field, the periodic removal of an oil sample and analysis of
the gas content serve to monitor the condition of transformers and other oil-filled equipment.
The importance of these techniques has led to the preparation of this standard, to the
procedures to be used for the sampling, from oil-filled electrical equipment, of gases and oils
containing gases, and for subsequent analysis.
NOTE Methods described in this standard apply to insulating oils, since experience to date has been almost
entirely with such oils. The methods may also be applied to other insulating liquids, in some cases with
modifications.
General caution, health, safety and environmental protection
This International Standard does not purport to address all the safety problems associated
with its use. It is the responsibility of the user of the standard to establish appropriate health
and safety practices and determine the applicability of regulatory limitations prior to use.
The insulating oils which are the subject of this standard should be handled with due regard to
personal hygiene. Direct contact with the eyes may cause irritation. In the case of eye
contact, irrigation with copious quantities of clean running water should be carried out and
medical advice sought. Some of the tests specified in this standard involve the use of
processes that could lead to a hazardous situation. Attention is drawn to the relevant standard
for guidance.
Mercury presents an environmental and health hazard. Any spillage should immediately be
removed and be properly disposed of. Consult local regulations for mercury use and handling.
Mercury-free methods may be requested in some countries.

– 8 – 60567 © IEC:2011
Environment
This standard is applicable to insulating oils, chemicals and used sample containers.
Attention is drawn to the fact that, at the time of writing of this standard, many insulating oils
in service are known to be contaminated to some degree by PCBs. If this is the case, safety
countermeasures should be taken to avoid risks to workers, the public and the environment
during the life of the equipment, by strictly controlling spills and emissions. Disposal or
decontamination of these oils should be carried out strictly according to local regulations.
Every precaution should be taken to prevent release of insulating oil into the environment.

60567 © IEC:2011 – 9 –
OIL-FILLED ELECTRICAL EQUIPMENT –
SAMPLING OF GASES AND ANALYSIS
OF FREE AND DISSOLVED GASES –
GUIDANCE
1 Scope
This International Standard deals with the techniques for sampling free gases from gas-
collecting relays from power transformers. Three methods of sampling free gases are
described.
The techniques for sampling oil from oil-filled equipment such as power and instrument
transformers, reactors, bushings, oil-filled cables and oil-filled tank-type capacitors are no
longer covered by this standard, but are instead described in 4.2 of IEC 60475:2011.
Before analysing the gases dissolved in oil, they are first extracted from the oil. Three basic
methods are described, one using extraction by vacuum (Toepler and partial degassing),
another by displacement of the dissolved gases by bubbling the carrier gas through the oil
sample (stripping) and the last one by partition of gases between the oil sample and a small
volume of the carrier gas (headspace). The gases are analysed quantitatively after extraction
by gas chromatography; a method of analysis is described. Free gases from gas-collecting
relays are analysed without preliminary treatment.
The preferred method for assuring the performance of the gas extraction and analysis
equipment, considered together as a single system, is to degas samples of oil prepared in the
laboratory and containing known concentrations of gases (“gas-in-oil standards”) and
quantitatively analyse the gases extracted. Two methods of preparing gas-in-oil standards are
described.
For daily calibration checks of the chromatograph, it is convenient to use a standard gas
mixture containing a suitable known amount of each of the gas components to be in a similar
ratio to the common ratios of the gases extracted from transformer oils.
The techniques described take account, on the one hand, of the problems peculiar to
analyses associated with acceptance testing in the factory, where gas contents of oil are
generally very low and, on the other hand, of the problems imposed by monitoring equipment
in the field, where transport of samples may be by un-pressurized air freight and where
considerable differences in ambient temperature may exist between the plant and the
examining laboratory.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for
transformers and switchgear
IEC 60475:2011, Method of sampling insulating liquids

– 10 – 60567 © IEC:2011
IEC 60599, Mineral oil-impregnated electrical equipment in service – Guide to the inter-
pretation of dissolved and free gases analysis
ISO 5725 (all parts), Accuracy (trueness and precision) of measurement methods and results
ASTM D2780, Standard Test Method for Solubility of Fixed Gases in Liquids
3 Sampling of gases from gas-collecting (Buchholz) relays
3.1 General remarks
It is important to bear in mind that receiving a qualitative and a representative sample is
crucial for obtaining a reliable diagnosis of the electrical equipment. Even the most
sophisticated extraction or diagnosis methods cannot overcome faulty samples.
Gas samples from relays should be taken from the equipment with the minimum delay after
gas accumulation has been signalled. Changes in composition caused by the selective re-
absorption of components may occur if free gases are left in contact with oil.
Certain precautions are necessary when taking gas samples. The connection between the
sampling device and the sampling vessel shall avoid the ingress of air. Temporary
connections should be as short as possible. Any rubber or plastic tubing used should have
been proved to be impermeable to gases.
Gas samples should be properly labelled (see Clause 4) and analysed without undue delay to
minimize hydrogen loss (for example, within a maximum period of one week).
Oxygen, if present in the gas, may react with any oil drawn out with the sample. Reaction is
delayed by excluding light from the sample, for example, by wrapping the vessel in aluminium
foil or suitable opaque material.
Of the three methods described below, the syringe method is recommended. The other two
methods are alternatives to be used exclusively in case of serious hindrance.
Sampling into a sampling tube by liquid displacement using transformer oil as a sealing liquid
is simple, but the different solubilities of the gas components may need to be taken into
account if the gas quantity is such that some oil remains in the tube.
The vacuum method requires skill to avoid contaminating the sample by leakage of air into the
system. It is particularly true where the gas to be sampled may be at less than atmospheric
pressure (for example, some sealed transformers).
3.2 Sampling of free gases by syringe
3.2.1 Sampling equipment
NOTE Figures in brackets refer to those circled numbers in the relevant figure.
See Figure 1. The equipment shall be as follows:
a) Impermeable oil-resistant plastic or rubber tubing (3) provided with a connecter to fit onto
a suitable sampling connection of the gas-collecting relay. To avoid cross-contamination,
the tubing should be used only once.
b) Gas-tight syringes of suitable volume (1) (25 ml to 250 ml). Medical or veterinary quality
glass syringes with ground-in plungers may be suitable; alternatively, syringes with oil-
proof seals may be used. The syringe should be fitted with a cock enabling it to be sealed.
It is often convenient to use the same syringes for both gas sampling and for oil sampling
(see 4.2.2 of IEC 60475:2011).

60567 © IEC:2011 – 11 –
The gas tightness of a syringe may be tested by storing an oil sample containing a
measurable quantity of hydrogen for at least two weeks and analysing aliquots for
hydrogen at the beginning and end of the period. An acceptable syringe will permit losses
of hydrogen of less than 2,5 % per week. General experience suggests that all-glass
syringes leak less than those using plastic seals. Improvement of the gas tightness may
be obtained by the use of a lubricant such as a light grease or transformer oil.
It is a good practice to test the integrity of syringes and valve system before the sampling.
A recommended procedure appears in Annex B of IEC 60475:2011.
c) Transport containers should be designed to hold the syringe firmly in place during
transport, but allow the syringe plunger freedom to move, and prevent its tip from
contacting the container, whatever its position during transportation.

A
Position
of valve
B
IEC  2457/11
Key
1 syringe 5 equipment sampling valve
2 stopcock 6 gas-collecting relay valve
3 rubber connecting tubing 7 waste vessel
4 three-way valve
Figure 1 – Sampling of gas by syringe
3.2.2 Sampling procedure
The apparatus is connected as shown in Figure 1. The connections should be as short as
possible and filled with oil at the start of sampling.
The sampling valve (5) is opened. If sampling from a gas-collecting relay on a transformer
fitted with a conservator, a positive pressure will exist; the three-way valve (4) is carefully
turned to position A and the oil in the connecting tubing (3) allowed to flow to waste (7). When
gas reaches the three-way valve (4), the latter is turned to position B to connect the pre-
lubricated syringe (1). The stopcock (2) is then opened and the syringe allowed to fill under
the hydrostatic pressure, taking care that its plunger is not expelled. When a sufficient sample

– 12 – 60567 © IEC:2011
has been taken, the stopcock (2) and sampling valve (5) are closed and the apparatus is
disconnected.
The oil in the syringe is expelled by inverting the syringe and applying gentle pressure to the
plunger.
Label carefully the sample (see Clause 4).
3.3 Sampling of free gases by displacement of oil
This method is reliable only where the gas sample is at or above atmospheric pressure. The
apparatus is shown in Figure 2.
The sampling tube (5), typically of 100 ml capacity, is preferably of glass since the operator
can then see how much oil remains in it during gas sampling. The sampling tube is filled with
oil from the transformer on site. Before being used as described below, the connecting tube
(3) should also be filled with oil.
The open end of the connecting tube (3) is fitted onto the gas-sampling valve (2). The
sampling valve and inlet stopcock of the sampling tube are opened. The sampling tube is
inclined so that its closed end is the lowest point. The outlet stopcock on the sampling tube is
then opened, allowing oil to run out to waste (6), drawing first any oil from the connection
between relay and sampling valve, and the gas from the relay, into the sampling tube.
Sampling is complete when the gas-collecting relay is completely filled with oil or when nearly
all oil has gone from the sampling tube.
Both stopcocks (4) on the sampling tube and the sampling valve (2) are closed and then the
connections removed.
IEC  2458/11
Key
1 gas collecting relay valve 4 stopcock
2 equipment sampling valve 5 sampling tube
3 oil-resistant connecting tubing 6 waste vessel
Figure 2 – Sampling of free gases by oil displacement

60567 © IEC:2011 – 13 –
3.4 Sampling of free gases by vacuum
The apparatus is connected as shown in Figure 3. With the equipment sampling valve closed,
stopcocks (1), (2) and (10) open, and the three-way valve (4) turned to position A, the vacuum
pump (12) is allowed to evacuate the connecting tubing, the trap and the sampling vessel.
A satisfactory vacuum will be below 100 Pa. The system should be checked for leaks by
closing the pump suction stopcock (10) and observing that no appreciable change in vacuum
occurs. Over a time equal to that which will be taken for sampling, the pressure should not
increase by more than 100 Pa. Similarly, the stopcock (1) on the sampling tube should be
vacuum tight to the same degree over several weeks.
If the connecting tubing between the equipment sampling valve (5) and the gas-collecting
relay is filled with oil, the three-way valve (4) is turned to position (B). The equipment
sampling valve (5) is carefully opened and oil allowed to flow into the trap (9). When the end
of the oil stream is observed to reach the three-way valve (4), it is turned to position D to
evacuate the oil from it. Thereafter, valve (4) is turned to position C. When sampling is
complete, stopcock (1) is closed first, then the equipment sampling valve (5) closed and the
apparatus disconnected.
If the connecting tubing between the equipment and the sampling valve is empty of oil, the
procedure for draining oil is omitted and the three-way valve (4) used in position C after
evacuating and testing that the apparatus is leak tight.

A
B
3 Position
of valve
C
D
IEC  2459/11
Key
1 vacuum tight stopcock 8 vacuum gauge
2 vacuum tight stopcock  9 trap
3 rubber connecting tubing 10 vacuum tight stopcock
4 vacuum tight three-way valve 12 vacuum pump
5 equipment sampling valve 28 sampling tube
6 gas collecting relay valve
Figure 3 – Sampling of free gases by vacuum

– 14 – 60567 © IEC:2011
3.5 Sampling of oil from oil filled equipment
See 4.2 to 4.4 of IEC 60475:2011.
4 Labelling of gas samples
Gas samples should be properly labelled before dispatch to the laboratory.
The following information, as shown in Table 1, is necessary (whenever it is known).
Table 1 – Information required for gas samples
Transformer Sampling
Customer Sampling date and time following a gas alarm
Location Sampling point
Identification number Sampling person
Manufacturer Reason for analysis
General type (power, instrument or Transformer non-energized, off-load energized
industrial) or on-load
Rated MVA
Voltage ratio
Type and location of OLTC
Date of commissioning
Oil
Type of oil (mineral or non-mineral) Weight (or volume) of oil
Product name Date of last oil treatment

The following additional information is desirable:
– ambient temperature, reading of MVA or load current or percentage load, operation of
pumps, mode of communication of its tap-changer with the main tank, oil preservation
system (conservator, nitrogen blanket, etc.), and any changes in operational conditions or
any maintenance carried out since last sampling;
– time of sampling where more than one sample is taken.
5 Sampling, labelling and transferring of oil from oil-filled equipment
5.1 Sampling and labelling of oil
Consult 4.2 to 4.4 of IEC 60475:2011 for sampling equipment, sampling procedures and
labelling to be used.
5.2 Transfer of oil for DGA analysis
5.2.1 General
For transferring oil from its sample container into the gas extraction vessels of Article 7, the
following procedures should be used:
5.2.2 Transfer from oil syringes
Introduce a portion of the oil sample in the syringe into the gas extraction vessel by turning
the three-way valve of the syringe to position B of Figure 5 of IEC 60475:2011.

60567 © IEC:2011 – 15 –
5.2.3 Transfer from ampoules
Attach the ampoule in the vertical position. Install a three-way plastic valve between the
bottom plastic tubing of the ampoule and another piece of plastic tubing going to a waste oil
container. Attach a glass syringe to the three-way plastic valve. Open the upper cock then the
lower cock of the ampoule. Fill the syringe with oil following procedures indicated in 4.2.2.2 of
IEC 60475:2011. Transfer a portion of the oil sample in the syringe into the gas extraction
vessel as indicated in 5.2.2 above.
5.2.4 Transfer from flexible metal bottles
Open the screw cap of the bottle, introduce a long needle down to the bottom of the bottle,
attach a glass syringe with a three-way valve to the needle and gently (to avoid creating gas
bubbles due to negative pressure) draw a sample of oil into the syringe. Detach the three-way
valve from the needle and invert the syringe to expel any gas bubble introduced in the oil.
Then introduce a portion of the oil sample in the syringe into the gas extraction chamber as
indicated in 5.2.2 above. Alternatively, a piece of tubing can be used to draw oil directly into
the gas extraction vessel (Toepler or partial degassing) under vacuum.
The first sample taken from the bottle should always be used for DGA analysis. No other
sample should be taken for DGA analysis, since significant gas loss may occur into the
headspace of the bottle.
5.2.5 Transfer from glass and rigid metal bottles
The procedure used for flexible metal bottles in 5.2.4 is suitable for glass and rigid metal
bottles.
6 Preparation of gas-in-oil standards
6.1 General remark
As noted in Clause 1, the pr
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