Capacitor voltage transformer (CVT) is one of the most important instrument transformers widely used to prepare the voltage signal for control and protection equipment. The measuring accuracy of CVT plays an important role in the proper operation of the protection system. Therefore, maintaining the accuracy of CVT throughout its lifetime at the desired level is of great significance, and proper maintenance activities must be implemented regarding the equipment conditions. Evaluating the reliability of the CVT over its lifetime is necessary to determine the proper maintenance. Until now, no proper model has been suggested to evaluate the reliability of CVT. Therefore, this paper proposes a new Markov model to evaluate the reliability of CVT. To obtain the model, initially, a Markov model is presented for each subsystem of CVT including capacitor voltage divider (CVD), electromagnetic unit (EMU), and high voltage bushing. Then, by integrating these models, a 10-state extended Markov model is proposed for CVT. Finally, by combining similar states, a 3-state model including healthy, low-quality and failure states is obtained. The simulation results show that the second capacitive group in the CVD subsystem, and the compensating reactor in the EMU subsystem play a major role in the CVT performance.

电容式电压互感器（CVT）是最重要的互感器之一，广泛用于为控制和保护设备准备电压信号。CVT 的测量精度对保护系统的正常运行起着重要作用。因此，在 CVT 的整个生命周期内将其精度保持在所需的水平具有重要意义，必须针对设备状况实施适当的维护活动。评估 CVT 在其整个生命周期内的可靠性对于确定适当的维护是必要的。到目前为止，还没有提出合适的模型来评估 CVT 的可靠性。因此，本文提出了一种新的马尔可夫模型来评估无级变速器的可靠性。为了获得模型，最初，为 CVT 的每个子系统提供了一个马尔可夫模型，包括电容器分压器 (CVD)、电磁单元 (EMU) 和高压套管。然后，通过整合这些模型，提出了用于 CVT 的 10 状态扩展马尔可夫模型。最后，通过组合相似的状态，得到包括健康、低质量和故障状态的三态模型。仿真结果表明，CVD子系统中的第二电容组和动车组子系统中的补偿电抗器对CVT性能起主要作用。