RAW (CT) serial coupling

Depending on the requirements the injection of ripple control signals generated by the transmitter may either be done by parallel coupling or by serial coupling. The serial coupling is a proven technology to inject especially ripple control frequencies between 160 Hz and 230 Hz.

The RAW injection transformers are connected into the power circuit and are, thus, in series with the 50/60 Hz power transformer. At the 50/60Hz they act as a conventional current transformer, while at the audio frequency of injection, they become power transformers.

The 50/60 Hz burden is made up of a series resonant circuit, which is tuned to become a parallel resonant circuit at audio frequency by means of an additional capacitor, in parallel, across same. The RAW is designed and constructed in accordance with the VDE specifications, as regards short-circuit power and interference / surge voltage ratings.

The injection transformers can either be mounted in outdoor switchyards or indoors, if required. The resonant circuit is installed together with the ripple control transmitter in an electrical switchgear room, where less than 1000 Volts is permissible.