Relative permittivity detector for cable insulators

This paper presents a new measurement technique of relative permittivity (ε_r) for cable insulators. The travelling wave and reflection wave theory are applied to generate low voltage pulse signal feeding cable lines that need to know ε_r of insulators. By measuring the interval of travelling wave, ε_r can be estimated for any types of cable lines. A prototype consists of pulse generator circuit, wave detection circuit, counter circuit and microcontroller unit for processing and display via LCD. This model is portable, compact, comfortable and capable of displaying ε_r value immediately. From the test results, this model has accuracy within acceptable values