IEC TR 62036:2007

Mineral insulating oils - Oxidation stability test method based on differential scanning calorimetry (DSC)

To develop a rapid oxidation stability test method based on differential scanning calorimetry (DSC) to assess the oxidation stability of mineral insulating oils

Huiles minérales isolantes - Méthode d'essai pour évaluer la stabilité d'oxydation fondée sur l'analyse calorimétrique différentielle par balayage

Le but de la CEI 62036 est d'élaborer une méthode d'essai de la stabilité à l'oxydation rapide fondée sur l'analyse calorimétrique différentielle par balayage (DSC) pour évaluer la stabilité à l'oxydation des huiles minérales isolantes

General Information

• Status: Published
• Publication Date: 10-Apr-2007
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.040.10 - Insulating oils
• Technical Committee: TC 10 - Fluids for electrotechnical applications
• Drafting Committee: WG 18 - TC 10/WG 18
• Current Stage: PPUB - Publication issued
• Start Date: 15-May-2007
• Completion Date: 11-Apr-2007

Standards Content (Sample)

TECHNICAL IEC
REPORT
CEI
TR 62036
RAPPORT
First edition
TECHNIQUE
Première édition
2007-04
Mineral insulating oils –
Oxidation stability test method based on
differential scanning calorimetry (DSC)

Huiles minérales isolantes –
Méthode d’essai pour évaluer la stabilité
d’oxydation fondée sur l’analyse calorimétrique
différentielle par balayage
Reference number
Numéro de référence
IEC/CEI/TR 62036:2007
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TECHNICAL IEC
REPORT
CEI
TR 62036
RAPPORT
First edition
TECHNIQUE
Première édition
2007-04
Mineral insulating oils –
Oxidation stability test method based on
differential scanning calorimetry (DSC)

Huiles minérales isolantes –
Méthode d’essai pour évaluer la stabilité
d’oxydation fondée sur l’analyse calorimétrique
différentielle par balayage
PRICE CODE
M
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
Pour prix, voir catalogue en vigueur

– 2 – TR 62036 © IEC:2007
CONTENTS
FOREWORD.3
INTRODUCTION.5

1 Scope.6
2 General remarks.6
3 Effect of temperature on oxidation induction time .6
3.1 Isothermal .6
3.2 Temperature-programmed runs .7
4 Effect of sample size on oxidation induction time.7
4.1 Inhibited oil .7
4.2 Uninhibited oil .7
5 Other factors effecting oxidation induction time .8
6 Reliability of method .8
7 Different instruments .8
8 Interpretation of curves.9
9 Conclusion .9

Bibliography.13

Table 1 – Oxidation induction time of oil samples at different temperature programmes.10
Table 2 – Oxidation induction time of oil samples at different sample weight.10
Table 3 – Repeatability of oxidation induction time by PDSC .10
Table 4 – Reproducibility of oxidation induction time by PDSC.11
Table 5a – DSC Results analyzed at different laboratories – Uninhibited oil.12
Table 5b – DSC Results analyzed at different laboratories – Inhibited oil.12

TR 62036 © IEC:2007 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MINERAL INSULATING OILS –
OXIDATION STABILITY TEST METHOD BASED ON DIFFERENTIAL
SCANNING CALORIMETRY (DSC)
FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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IEC 62036, which is a technical report, has been prepared by IEC technical committee 10:
Fluids for electrotechnical applications.

– 4 – TR 62036 © IEC:2007
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
10/676/DTR 10/690/RVC
Full information on the voting for the approval of this technical report 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
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the data related to the specific publication. At this date, the publication will be
• reconfirmed,
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• replaced by a revised edition, or
• amended.
TR 62036 © IEC:2007 – 5 –
INTRODUCTION
The existing methods to assess oxidation stability of mineral insulating oil are very time
consuming. A faster method is necessary for effective quality control and status monitoring.
Differential scanning calorimetry (DSC) as a technique has been used for monitoring grease
and lubricants oxidation stability. The use of DSC for evaluation of oil oxidation stability was
originally suggested to IEC, TC 10 following publication of a literature review of DSC oxidation
tests performed on petroleum products (10/367/INF April 1996). During IEC’s TC 10 meeting
in Geneva, 1998, it was decided to set up a working group for development of a standard
based on DSC for rapid evaluation of mineral insulating oil oxidation stability.

– 6 – TR 62036 © IEC:2007
MINERAL INSULATING OILS –
OXIDATION STABILITY TEST METHOD BASED ON DIFFERENTIAL
SCANNING CALORIMETRY (DSC)
1 Scope
The purpose of IEC 62036, which is a technical report, is to develop a rapid oxidation stability
test method based on differential scanning calorimetry (DSC) to assess the oxidation stability
of mineral insulating oils.
2 General remarks
The main function of insulating oil is insulation and cooling. The expected life span of
transformer oil is 25 to 40 years, largely depending on operating temperature and electrical
load. Specifications are prepared and used to fulfil all criteria required for proper functioning
of the oil in service. Life expectancy from insulating oil has a large economic impact on the
cost of operation of a unit.
The oxidation stability test is an important test as this will evaluate, to some extent, the life of
the oil in service. Resistance of an oil oxidation is very much dependant on the refining
process and type of crude oil. Both under-refined and over-refined oils may exhibit poor
oxidation stability. The complex process of oxidation of in-service oils occurs slowly at the
normal operating temperature of the transformer and is dependant on temperature, oxygen
and catalyst. In the first stage of oil oxidation, radicals and peroxides are produced. These
compounds are unstable and rapidly convert to volatile and soluble acids and finally
producing insoluble material or sludge. All of these products have an adverse effect on
electrical and physical properties of oil. The oil may reach a stage where it is not fit for its
intended purpose.
To establish a long service life for the oil, an oxidation stability test is performed on the
u
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