IEC 60970:2007

Insulating liquids - Methods for counting and sizing particles

Describes the sampling procedures and methods for the determination of particle concentration and size distribution. Three methods are specified. One uses an automatic particle size analyser, working on the light interruption principle. The other two use an optical microscope, in either the transmitted light or incident light mode, to count particles collected on the surface of a membrane filter. The optical microscope methods are described in ISO 4407. All three methods are applicable to both used and unused insulating liquids. Annex A contains an alternative sampling procedure using a syringe and Annex B reports a reference for the calibration of automatic particle counters. The significant technical changes with respect to the previous edition are as follows: - new calibration procedures for automated laser particle; - three figures contamination code; - new procedure of sample pre-treatment when automated laser counter method are used.

Isolants liquides - Méthodes de détermination du nombre et de la taille des particules

Décrit les procédures de prélèvement et les méthodes pour déterminer la concentration des particules et la répartition selon leur taille. Trois méthodes sont recommandées. L'une d'entre elles utilise un analyseur automatique de particules, dont le principe repose sur l'interruption d'un faisceau lumineux. Les deux autres utilisent un microscope optique, en mode soit de lumière transmise soit de lumière incidente, pour compter les particules retenues à la surface d'une membrane filtrante. Les méthodes au microscope optique sont décrites dans l'ISO 4407. Ces trois méthodes sont applicables tant aux isolants liquides usagés qu'aux isolants liquides neufs. L'Annexe A comporte une autre procédure d'échantillonnage utilisant une seringue et l'Annexe B indique une référence pour l'étalonnage des compteurs automatiques de particules. Les principales modifications techniques par rapport à l'édition précédente sont les suivantes: - nouvelles procédures d'étalonnage pour les analyseurs automatiques de particules; - code de contamination à trois chiffres; - nouvelle procédure pour le pré-traitement d'échantillons quand la méthode des compteurs de particules automatisés est utilisée.

General Information

• Status: Published
• Publication Date: 15-Jul-2007
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.220.99 - Other standards related to electricity and magnetism
• ICS: 29.040.10 - Insulating oils
• Technical Committee: TC 10 - Fluids for electrotechnical applications
• Current Stage: PPUB - Publication issued
• Start Date: 30-Sep-2007
• Completion Date: 16-Jul-2007

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD
CEI
NORME
Second edition
INTERNATIONALE
Deuxième édition
2007-07
Insulating liquids – Methods for counting and
sizing particles
Isolants liquides – Méthodes de détermination du
nombre et de la taille des particules

Reference number
Numéro de référence
IEC/CEI 60970:2007
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INTERNATIONAL IEC
STANDARD
CEI
NORME
Second edition
INTERNATIONALE
Deuxième édition
2007-07
Insulating liquids – Methods for counting and
sizing particles
Isolants liquides – Méthodes de détermination du
nombre et de la taille des particules
PRICE CODE
R
CODE PRIX
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
Pour prix, voir catalogue en vigueur

– 2 – 60970 © IEC:2007
CONTENTS
FOREWORD.3
INTRODUCTION.5

1 Scope.6
2 Normative references .6
3 General caution, health, safety and environmental protection .6
4 Significance.7
5 Comparison and limitation of the methods .7
6 Types and identification of particles.8
7 Sampling .8
7.1 General remarks.8
7.2 Sampling vessels .9
7.3 Cleaning of sampling bottles .9
7.4 General directions for sampling .9
7.5 Sampling procedure .10
7.6 Labelling of samples.10
7.6.1 Samples from tanks .10
7.6.2 Samples from electrical equipment .10
8 Preparation of the samples for analysis .10
9 Method A – Automatic particle size analyzer.11
9.1 Summary of method .11
9.2 Apparatus and auxiliary materials.11
9.3 Calibration procedures .11
9.4 Preparation of the apparatus for counting.12
9.5 Preparation of sample before counting .12
9.6 Preparation of sample for counting .12
9.7 Counting procedures .12
9.8 Report .13
9.9 Precision .13
9.10 Repeatability .13
9.11 Reproducibility .13
10 Method B – Optical microscopy .14
10.1 Principle.14
10.2 Procedure by transmitted light .14
10.3 Procedure by incident light .14

Annex A (informative) Use of syringes as sampling vessels .15
Annex B (informative) Calibration of the automatic particle counters .17

Bibliography.18

60970 © IEC:2007 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATING LIQUIDS – METHODS FOR COUNTING AND SIZING
PARTICLES
FOREWORD
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International Standard IEC 60970 has been prepared by IEC technical committee 10: Fluids
for electrotechnical applications.
This second edition cancels and replaces the first edition published in 1989. This edition
constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows:
– new calibration procedures for automated laser particle;
– three figures contamination code;
– new procedure of sample pre-treatment when automated laser counter method are used.

– 4 – 60970 © IEC:2007
The text of this standard is based on the following documents:
FDIS Report on voting
10/695/FDIS 10/714/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.
60970 © IEC:2007 – 5 –
INTRODUCTION
The first edition of this standard was published in 1989, and confirmed in 1996. The present
edition has been found necessary for consistency with the new ISO 4406:1999, in which
calibration procedures for automated particles counters have been changed from ACFTD
standard to ISO-MTD standard. Specific procedures for sample preparation are described in
more detail when automated particle counters are used. Results and ISO Code reporting are
consistent with ISO 4406:1999 standard. Repeatability and reproducibility data are reported.
It has been demonstrated that particle contamination of insulating liquids used in electrical
equipment have been responsible for major faults [1] . Particle analysis is recommended (as
complementary test) by IEC 60422[3] for power transformers with nominal voltage above
170 kV[2].
Particle counting and sizing is usually carried out using automated counters; the calibration
...