IEC 60247:2004

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 General
   4.1 Permittivity and dielectric dissipation factor (tan
        delta)
   4.2 Resistivity
   4.3 Sequence of determinations
   4.4 Factors leading to erroneous results
5 Apparatus
   5.1 Test cell
   5.2 Test equipment
   5.3 Glassware
   5.4 Measuring instrument for permittivity and tan delta
   5.5 Measuring instrument for d.c. resistivity
   5.6 Time-measuring device
   5.7 Safety
6 Cleaning solvent
7 Cleaning the test cell
   7.1 Trisodium phosphate cleaning procedure
   7.2 Storage of cell
8 Sampling
9 Preparation of samples
10 Conditioning and filling the test cell
   10.1 Cell conditioning
   10.2 Filling the cell
11 Test temperature
12 Measurement of dissipation factor (tan delta)
   12.1 Test voltage
   12.2 Measurement
   12.3 Report
13 Measurement of relative permittivity
   13.1 Measurement
   13.2 Report
14 Measurement of d.c. resistivity
   14.1 Test voltage
   14.2 Time of electrification
   14.3 Measurement
   14.4 Report
Annex A (informative) Example of an alternative procedure for
                      cleaning the test cell - Ultrasonic
                      procedure
Annex B (informative) Example of a simplified cleaning
                      procedure for a test cell
Annex C (informative) Alternative procedures for routine testing
                      of dielectric dissipation factor and
                      resistivity of insulating liquids
Figure 1 - Example of a three-terminal cell for measurements on
           liquids
Figure 2 - Example of screening for the cell of Figure 1
Figure 3 - Example of assembling drawing of cell
Figure 4 - Example of a two-terminal cell for measurements in
           liquids
Figure 5 - Example of a test cell designed for low-loss
           dielectric liquids

Describes methods for the determination of the dielectric dissipation factor, relative permittivity and d.c. resistivity of any insulating liquid material at the test temperature. The methods are primarily intended for making reference tests on unused liquids. They can also be applied to liquids in service in transformers, cables and other electrical apparatus. However the method is applicable to a single phase liquid only. When it is desired to make routine determinations, simplified procedures, as described in Annex C, may be adopted. With insulating liquids other than hydrocarbons, alternative cleaning procedures may be required. The main changes from the previous edition deal with the preferred measurement method.