BS 4542:1970

Cooperating organizations
Foreword
Method
1. Scope
2. Principle of method
3. Accuracy and range
4. Temperature of test specimen, and test frequency
5. Apparatus: the electrodes
6. Apparatus: the bridge network
7. The specimen
8. Method
9. Calculation
Appendix
A. Bridge apparatus
Figures
1. General arrangement of electrode system
2. Method of introducing small variable conductance
3. Five-arm network

Accuracy and range, description of the apparatus, the form of specimen, procedures to be followed and the necessary calculation for determination over a frequency range of 1 kHz to 100 kHz. Precautions are given for extending the range to 1 MHz. Supplements the Hartshorn and Ward method of BS 2067.

This British Standard describes the Lynch method for the determination of the loss tangent and the permittivity of insulating materials at frequencies of 1 kHz to 100 kHz at normal room temperatures. It gives details of the apparatus and of the procedure to be followed.

The frequency range can be extended downward to 50 Hz unless the surface resistivity of the specimen is low (e.g. 10¹⁰ Ω). It can be extended upward to 1 MHz by taking the precautions suggested in Clause 6 and in Appendix A.