提出一种基于角度变量的变压器差动保护动作特性试验方法:通过改变保护测试仪输出电流的角度以产生差流使保护装置动作,再按照三角函数计算出差动和制动电流,从而得到比率制动系数。试验证明,该方法的试验步骤、计算公式简单,计算结果准确,试验效率较高。

阐述了SF_6断路器智能控制器的原理与结构,给出了断路器状态信息的采集方法,提出采用光纤实现监控中心对断路器状态的监视。

Presently,most of electronic voltage transformer applies theory of voltage dividing to supply secondary voltage signals and there is not enough electric isolation between the primary and secondary circuit.For this reason,a new type of electronic voltage transformer based on spiral air-core coil current sensor is proposed.In series with the capacitor,the current sensor can detect the current in it to reflect the primary high voltage.As current sensor,the spiral air-core coil has good linearity,big bandwidth without magnetic saturation problem.To meet different requirements of measurement accuracy ratings,two signal processing circuits are provided to supply with related voltage signals.Power amplifiers are adopted in the signal processing circuit to guarantee against losing capability of sustaining secondary load.The experiment data indicate that the electronic voltage transformer has fast dynamic response,a big bandwidth and high linearity.