Transient conditions in CCVTs outputs and their effects on the detection of traveling waves

Abstract

It can be considered that coupling capacitor voltage transformers have two outputs. The first is the fundamental frequency output, normally used to feed relays and meters. This output has a limited bandwidth and its response is typical of a low-pass filter. The second is the high-frequency output, normally used for Power Line Carrier application. This paper demonstrates, by means of digital simulations conducted with EMTP/ATP, that it is possible to capture, using the second output, the appropriate traveling wave voltage signals that are required for the correct operation of an EHV transmission line fault locator system, for line maintenance purposes. This paper also demonstrates that, due to the behaviour of the high-frequency output, it is possible to obtain the voltage information that is needed to locate lightning discharges that reach the line and do not cause insulator flashover. This information can be very important for transmission line maintenance purposes.