IEC 62701:2014

IEC 62701


®


Edition 1.0 2014-03



INTERNATIONAL



STANDARD



NORME
INTERNATIONALE


Fluids for electrotechnical applications – Recycled mineral insulating oils for
transformers and switchgear

Fluides pour applications électrotechniques – Huiles minérales isolantes
recyclées pour transformateurs et appareillages de connexion


IEC 62701:2014-03(en-fr)

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IEC 62701



®



Edition 1.0 2014-03







INTERNATIONAL





STANDARD







NORME



INTERNATIONALE











Fluids for electrotechnical applications – Recycled mineral insulating oils for

transformers and switchgear




Fluides pour applications électrotechniques – Huiles minérales isolantes

recyclées pour transformateurs et appareillages de connexion

















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX N


ICS 29.040 ISBN 978-2-8322-1121-2



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 62701:2014  IEC 2014


CONTENTS



FOREWORD . 3

INTRODUCTION . 5

1 Scope . 6


2 Normative references . 6

3 Terms and definitions . 8

4 Properties of oil – Refining and stability . 9


5 Classification, identification, general delivery requirements . 9
5.1 Classification . 9
5.2 Requirements . 9
5.3 Miscibility . 9
5.4 Identification and general delivery requirements . 9
6 Properties, their significance and test methods . 9
6.1 Water content . 9
6.2 Acidity . 10
6.3 Antioxidant additives . 10
6.4 Gassing tendency . 10
6.5 Polycyclic aromatics content (PCAs) . 10
6.6 Polychlorinated biphenyl content (PCBs) . 10
6.7 2-Furfural (2-FAL) and related compounds content . 11
6.8 Particle content . 11
6.9 DBDS content. 11
6.10 Stray gassing of oil . 11
Bibliography . 14

Table 1 – General specifications . 12

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IEC 62701:2014  IEC 2014 – 3 –


INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________



FLUIDS FOR ELECTROTECHNICAL APPLICATIONS –

RECYCLED MINERAL INSULATING OILS

FOR TRANSFORMERS AND SWITCHGEAR





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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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.
International Standard IEC 62701 has been prepared by IEC technical committee 10: Fluids

for electro technical applications.
This International Standard is in line with IEC 60296 and IEC 60422.
The text of this standard is based on the following documents:
FDIS Report on voting
10/908/FDIS 10/910/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.

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– 4 – IEC 62701:2014  IEC 2014


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.

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IEC 62701:2014  IEC 2014 – 5 –


INTRODUCTION


Health and safety


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 mineral 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.
Environment
This standard is applicable rise to mineral insulating oils, chemicals and used sample
containers. The disposal of these items shall be carried out according to the local regulations
with regard to the impact on the environment. Every precaution should be taken to prevent
release of mineral insulating oil into the environment.

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– 6 – IEC 62701:2014  IEC 2014


FLUIDS FOR ELECTROTECHNICAL APPLICATIONS –

RECYCLED MINERAL INSULATING OILS

FOR TRANSFORMERS AND SWITCHGEAR








1 Scope


This International Standard specifies requirements for recycled mineral insulating oils

intended for use in transformers, switchgear, and similar electrical equipment in which oil is
required for insulation and heat transfer.
These oils are produced by processes employed offsite.
Oils treated and reconditioned on-site are not within the scope of this standard.
Oils with and without additives are within the scope of this standard.
Such oils will have originally been supplied in compliance with a recognized unused mineral
insulating oil specification.
This standard does not differentiate between the methods used to recycle mineral insulating
oil.
This standard does not apply to mineral insulating oils used as impregnates in cables or
capacitors.
For the purpose of this standard the following subclauses of IEC 60296:2012 apply:
– 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9;
– 4.1, 4.3, 4.4;
– 5.1, 5.5;
– 6.1, 6.2, 6.4, 6.5, 6.6, 6.8, 6.9, 6.10, 6.11.1, 6.11.3, 6.11.4, 6.12, 6.14, 6.15, 6.16;
– 7.1.
NOTE Some types of re-refined oils are equivalent to unused oils in terms of performance, in which case IEC
60296 is applicable. This should be stated by the manufacturer.

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 60156, Insulating liquids – Determination of the breakdown voltage at power frequency –
Test method
IEC 60247, Insulating liquids – Measurement of relative permittivity, dielectric dissipation
factor (tan δ) and d.c. resistivity
IEC 60296:2012, Fluids for electrotechnical applications – Unused mineral insulating oils for
transformers and switchgear

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IEC 62701:2014  IEC 2014 – 7 –


IEC 60422, Mineral insulating oils in electrical equipment – Supervision and maintenance

guidance


IEC 60628, Gassing of insulating liquids under electrical stress and ionization


IEC 60666, Detection and determination of specified additives in mineral insulating oils


IEC 60814, Insulating liquids – Oil-impregnated paper and pressboard – Determination of

water by automatic coulometric Karl Fischer titration


IEC 60970, Insulating liquids – Method for counting and sizing particles

IEC 61125:1992, Unused hydrocarbon based insulating liquids – Test methods for evaluating
the oxidation stability
Amendment 1 (2004)
IEC 61198, Mineral insulating oils – Methods for the determination of 2-furfural and related
compounds
IEC 61619, Insulating liquids – Contamination by polychlorinated biphenyls (PCBs) – Method
of determination by capillary column gas chromatography
IEC 61620, Insulating liquids – Determination of the dielectric dissipation factor by
measurement of the conductance and capacitance – Test method
IEC 61868, Mineral insulating oils – Determination of kinematic viscosity at very low
temperatures
IEC 62021-1, Insulating liquids – Determination of acidity – Part 1: Automatic potentiometric
titration
IEC 62021-2, Insulating liquids – Determination of acidity – Part 2: Colorimetric titration
IEC 62535, Insulating liquids – Test method for detection of potentially corrosive sulphur in
used and unused insulating oils
IEC 62697-1, Test methods for quantitative determination of corrosive sulfur compounds in
unused and used insulating liquids – Part 1: Test method for quantitative determination of
dibenzyldisulfide (DBDS)

ISO 2719, Determination of flash point – Pensky-Martens closed cup method
ISO 3016, Petroleum products – Determination of pour point
ISO 3104, Petroleum products – Transparent and opaque liquids – Determination of kinematic
viscosity and calculation of dynamic viscosity
ISO 3675, Crude petroleum and liquid petroleum products – Laboratory determination of
density – Hydrometer method
ISO 12185, Crude petroleum and petroleum products – Determination of density – Oscillating
U-tube method
ISO 14596, Petroleum products – Determination of sulfur content – Wavelength-dispersive X-
ray fluorescence spectrometry

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– 8 – IEC 62701:2014  IEC 2014


ASTM D971, Standard Test Method for Interfacial Tension of Oil Against Water by the Ring

Method


DIN 51353, Testing of insulating oils; detection of corrosive sulfur; silver strip test


EN 14210, Surface active agents – Determination of interfacial tension of solutions of surface

active agents by the stirrup or ring method


IP 346, Determination of polycyclic aromatics in unused lubricating base oils and asphaltene

free petroleum fractions – Dimethylsulfoxide extraction refractive index method


IP 373, Petroleum products – Determination of sulphur content – Oxidative microcoulometry
method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60296, as well as
the following apply.
3.1
recycled mineral insulating oil
general term to encompass mineral insulating oils previously used in electrical equipment that
has been subjected to re-refining or reclaiming(regeneration) off-site
Note 1 to entry: The characteristics of recycled oil are heavily dependent on the crude from which it was refined,
the original refining technique, the service history and the type of recycling process. Natural antioxidants originally
present in the oil might have been depleted in service or removed by the recycling process.
Note 2 to entry: Recycled oil is not appropriate for use in some applications.
Note 3 to entry: Such recycled oils are often produced from mixtures of mineral insulating oils of different origins.
Note 4 to entry: A blend of unused and recycled oils in any proportion is regarded as being recycled oil.
Note 5 to entry: Due to local legislation, in some countries, it is advisable to categorize used electrical oil as
waste oil and complete separation of handling of unused and used oils is required
3.2
Reclaimed(regenerated) mineral insulating oil
mineral insulating oil used in electrical equipment, which has been subjected to chemical and
physical processing to eliminate soluble and insoluble contaminants
Note 1 to entry: Where these processes are performed on oil contained in equipment in service, so called “on-site

reclamation”, such treated oils are beyond the scope of this standard.
3.3
reconditioned mineral insulating oil
mineral insulating oil used in electrical equipment, which has been subjected to a physical
process to remove insoluble contaminants and free water and to reduce the levels of
dissolved moisture and gases
3.4
re-refined mineral insulating oil
mineral insulating oil used in electrical equipment that has been removed from service and
subjected to a process similar to that used for the production of unused mineral insulating oil
from virgin feedstock, including distillation and hydrogenation, in order to reduce the level of
unwanted compounds
Note 1 to entry: Such re-refined oils are often produced from mixtures of mineral insulating oils of different
origins.

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IEC 62701:2014  IEC 2014 – 9 –


4 Properties of oil – Refining and stability


Properties of oil are influenced by quality and type of the original oil refining, used oil

recycling and additives.


NOTE These properties can include appearance, interfacial tension, sulphur content, acidity, corrosive sulphur,

2-furfural and related compounds content and stray gassing.


5 Classification, identification, general delivery requirements


5.1 Classification

For the purposes of this standard, recycled mineral insulating oils are classified as in 5.1 of
IEC 60296:2012.
5.2 Requirements
The general requirements of this standard are given in Table 1.
5.3 Miscibility
Recycled mineral insulating oils of the same class (see 5.1.1 of IEC 60296:2012), the same
group (see 5.1.2 of IEC 60296:2012), the same LCSET (see 5.1.3 of IEC 60296:2012) and
containing the same types of additives are considered to be miscible and compatible with
each other (see also IEC 60422).
5.4 Identification and general delivery requirements
The following applies:
a) Oil is normally delivered in bulk, rail tank cars, tank containers or packed in drums or IBC
(intermediate bulk containers). These shall be clean and suitable for this purpose to avoid
any contamination.
b) Oil drums and IBC containers shall carry at least the following markings:
– supplier's designation;
– classification (see 5.1 of IEC 60296:2012);
– oil quantity;
– recycled oil compliant with IEC 62701.
c) As agreed between the supplier and purchaser, each oil delivery shall be accompanied by
a document specifying the supplier’s designation, oil classification, compliance certificate

and process of recycling.
d) The supplier shall declare the generic type of all additives, and their concentrations in the
cases of inhibitors and passivators.
NOTE This document is intended to be traceable to a specific batch of oil produced.
6 Properties, their significance and test methods
6.1 Water content
A low water content of mineral insulating oil is necessary to achieve adequate breakdown
voltage and low dissipation losses. To avoid separation of free water, recycled mineral
insulating oil shall have limited water content. Before filling the electrical equipment, the oil
should be treated to meet the requirements of IEC 60422. Water content shall be measured in
accordance with IEC 60814.

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– 10 – IEC 62701:2014  IEC 2014


6.2 Acidity


Recycled mineral insulating oil should have been treated to remove acidity and oxidation by-

products. Acidity shall be measured according to IEC 62021-1 or IEC 62021-2.


6.3 Antioxidant additives

Antioxidants (see 3.5 of IEC 60296:2012) slow down the oxidation of oil and therefore the
formation of degradation products such as oil sludge and acidity. It is necessary to know the

concentration of antioxidants for the correct classification of the oil. Additionally, the actual

concentration is required to monitor ageing of the oil.


Additives that slow down the oxidation of mineral insulating oils include:
– inhibitors such as phenols and amines (see 3.5.1 of IEC 60296:2012). The most widely
used inhibitors are di-tert-butyl-para-cresol (DBPC) and di-tert-butyl-phenol (DBP).
Detection and measurement of DBPC and DBP shall be carried out in accordance with
IEC 60666. IEC test methods are not available for other types of inhibitors;
– other antioxidant additives such as sulphur- and phosphor-containing compounds, e.g.
organic polysulphides and dithiophosphates (see 3.5.2 of IEC 60296:2012). An antioxidant
additive of this type is dibenzyl disulphide (DBDS) (see 6.10 of IEC 60296:2012), but it is
not accepted in recycled oils as it is known to be corrosive to copper and will likely result
in the oil failing the potentially corrosive sulphur test IEC 62535. The IEC 62697-1 test
method was prepared only for DBDS (see 6.9 below) and not for the other antioxidant
additives of this type;
– metal passivators (see 3.5.3 and 6.11.3 of IEC 60296:2012).
6.4 Gassing tendency
Gassing tendency of mineral insulating oil, i.e. the gas absorbing property of oil when
subjected to corona partial discharges, is only necessary and important for special equipment
like HV (high voltage) instrument transformers and bushings. It is a measure of the rate of
absorption or evolution of gas into oil under prescribed laboratory conditions. Gas absorption
properties could be related to oil aromatic content. Gassing tendency shall be measured using
method A of IEC 60628.
NOTE Additives such as 1,2,3,4 tetrahydronaphtalene (tetralin), mono or dibenzyltoluene and others have been
proposed to reduce the gassing tendency of some oils, but are not described in IEC 60666. Mono and
1
dibenzyltoluene are described in IEC 60867 [1] .
6.5 Polycyclic aromatics content (PCAs)
Some PCAs are classified to be carcinogens and therefore need to be controlled to an
acceptable level in mineral insulating oil. The total amount of PCAs can be measured by

extraction with DMSO (dimethylsulfoxide) under the conditions of IP 346.
NOTE 1 Acceptable limits of total or individual PCAs are specified in national and local regulations.
NOTE 2 Values and limits as given in IP 346 are substantiated for virgin base oils only.
6.6 Polychlorinated biphenyl content (PCBs)
Recycled mineral insulating oil shall be free from PCBs. The reference test method shall be
IEC 61619.
NOTE Acceptable limits of total or individual PCBs are specified in national and local regulations. Further
European specifications are described in Directive CE/59/96 [2].
—————————
1
 References in square brackets refer to the Bibliography.

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IEC 62701:2014  IEC 2014 – 11 –


6.7 2-Furfural (2-FAL) and related compounds content


2-FAL and related compounds in recycled mineral insulating oils can result from improper

redistillation after solvent extraction, from cellulose degradation within equipment that

previously contained the oil or from contamination with used oil.


Recycled mineral insulating oils should have a low level of 2-FAL and related compounds;

measurement shall be carried out according to IEC 61198.


NOTE 1 The “related compounds” are: 5-hydroxymethyl-2-furfural (5HMF), 2-furfurylalcohol (2FOL), 2-acetylfuran

(2ACF) and 5-methyl-2-furfural (5MEF).

NOTE 2 Not all recycling processes will be able to eliminate all furanic c
...