BS 7663:1993
Current
The latest, up-to-date edition.
Methods of test for determination of permittivity and dissipation factor of electrical insulating material in sheet or tubular form
Hardcopy , PDF
English
15-07-1993
Committees responsible
Foreword
Methods
Introduction
1 Scope
2 References
3 Definitions
4 General
5 Test conditions
6 Number and handling of specimens
7 Measuring instruments
8 Method A: Air substitution technique
9 Method B: Two fluid immersion technique
10 Method C: Single fluid immersion technique
11 Precision
12 Test report
Annexes
A (informative) Modes of representation of
capacitance
B (informative) Liquids of known permittivity values
Figures
1 Example of electrode system for method A
2 Example of electrode system for method B: sheet
specimens
3 Example of electrode system for method B: tubular
specimens
4 Example of electrode system for method C
A.1 Equivalence of series and parallel representations
of a capacitor
List of references
Three methods are described at frequencies between 50 Hz and 1 MHz.
| Committee |
PRI/22
|
| DevelopmentNote |
Supersedes 91/48847 DC (10/2005) Reviewed and confirmed by BSI, November 2008. (11/2008)
|
| DocumentType |
Standard
|
| Pages |
18
|
| PublisherName |
British Standards Institution
|
| Status |
Current
|
| Supersedes |
This British Standard describes three methods for the measurement of permittivity and of dissipation factor of electrical insulating materials in the form of sheets or rigid circular tubes at frequencies between 50 Hz and 1 MHz, under normal ambient temperatures and conditions. The methods described are applicable to sheet materials in the thickness range 0.3 mm to 5.0 mm and for tubes at least 75 mm long.
The methods are:
- an air substitution method, commonly called the “Lynch?? method (method A)
- a two fluid immersion method (method B)
- a single fluid immersion method (method C).
Methods A and B are suitable for materials of permittivity up to 10.0. For materials of dissipation factor below 250 × 10–6 the precision achieved by these methods may not be acceptable.
Method A requires accurate knowledge of the specimen thickness and should be used in all cases when this information is available. If the thickness is not accurately known, methods B or C may be used subject to the limitation that method C is suitable for materials for which a liquid matching its permittivity to within 0.1 is available. Method C is suitable for measurement of polyolefin sheets whose permittivity sufficiently closely matches that of silicone oil of kinematic viscosity of 1 cSt to 2 cSt1).
Methods B and C are not suitable for materials with an open cell structure.
Method B is suitable for measurements on straight cylindrical tubes of circular cross section.
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