The square wave voltage method for the measurement of low level tan δ of liquid dielectrics

This paper describes a technique that measures conductance and capacitance of a liquid sample under quasi square wave voltage excitation and derives its dissipation factor (tan δ) from these two parameters. The technique offers possibilities of higher accuracy of tan δ measurement over traditional AC methods. The principle of this technique and various topics in relation to its implementation are discussed. The settling time of the measurement system as a whole is also discussed together with derived mathematical expressions and simulation results. Agreement between this method and the AC bridge method is demonstrated with tan δ measurements on a number of insulating oil samples