电介质超慢弛豫过程的研究

本文提出的线变零电压起始法克服了过零法1]反复充放电时间太长,起始阶跃电压所造成的吸收电流难以完全消除等缺点,因而可以迅速准确地测定电介质的超慢弛豫特性。比较电介质的充放电电流的时间关系,可以确定其瞬时绝缘电阻。采用多重非线性最小二乘方对实验结果进行拟合处理,可以分离材料中的各种弛豫机构并获得相应的弛豫参数,拟合结果与实验结果吻合良好,其差值通常均低于1％。根据德拜方程可以从实测的C-t关系中得到材料介电常数与损耗角正切的超低频频谱及相应的Cole-Cole图。

A STUDY ON ULTRA SLOW DIELECTRIC RELAXATION

Difficulties encountered in zero-crossing method, such as, overlong charg- ing and discharging time and innegligible absorption current resulting from the starting voltage pulse can be overcome by using the zero-starting method proposed in this paper. Ultra slow dielectric relaxation behaviors can be measured easily and precisely. Intrinsic transient conduction resistance of the sample can be ob- tained by subtracting the discharging current from the charging current. Separa- tion of fast and slow relaxations can be achieved by using the multi-nonlinear least square method to fit the C-t curve to theoretical equation. Very good fit- ting, better than 1% in many cases, has been achieved. Important dielectric re- laxation parameters can be obtained from the fitting. Ultra low frequency spectra of dielectric constant and loss tangent as well as the Cole-Cole diagram can be obtained from the C-t curve by using the Debye equations and the relaxation parameters.