介质损失角正切（tgδ）计算的新方法

A NEW METHOD FOR CALCULATING THE TANGENT OF DIELECTRICAL LOSS ANGLE(tgδ)

介质损失角正切ｔｇδ的测量在电气设备制造、绝缘材料鉴定和电气设备的绝缘试验方面都得到广泛的应用。它是判断绝缘情况的一个较灵敏的方法，特别是对于受潮、老化等分布性缺陷比较有效，对小体积设备比较灵敏，因而它是绝缘试验中一个较重要的项目。对电气设备进行该项试验，很难在全变电站停电情况下进行，必然要遇到外电场的干扰。随着电力工业的发展，输电电压等级的不断提高，所遇到的电场干扰问题也就愈加突出。因此，对于在电场干扰下如何准确地测定、计算ｔｇδ值，本文提出了一种方法。从电桥的正接线、反接线和侧接线方式人手进行分析，导出在试验电压极性变化前后电桥回路各参数间的关系，进而找到存在外电场干扰时计算介质损失角正切的一种方法。实践证明，该方法在电场干扰下计算简单、准确、可行。

The measurement of the tangent of dielectrical loss angle is widely used inmanufacturing electic devices, appraising the quality of insulation materials and testing for theinsulation of electric devices. The tangent of dielectrical loss angle can sensitived identifies insulation quality, it is especially valid for existness and ageing, and more accurate for small device in volume, then, it is a more important subject in insulation testing. When we do thistest it is quite difficulty to make sure that the power substation is interruption, so, there will bethe disturbance of outer electric field in the test. With the development of electrical power in industry,the gradation of transmission voltage is increasing the problem of disturbance is moreobvious. Under the disturbance of electric field, one kind of method to accurately measure andcalculate tgδ is proposed in this paper. By analyzing the straight, opposition and side jointforms of bridge, the relations between parameters in the bridge loop are obtained underchanging the polarity of test voltage, and the method for calculating tangent of dielectrical lossangle under disturbance of electric is then found. In practice,it proves that the method issimple, accurate and valid for computation.