The electronic part of the NCCTS (and Non-
Conventional Voltage Transformers) which processes the
information must have a power supply. The necessary
power can only come from the station’s batteries. This
power supply is provided in a simple manner when the
secondary electronics are in the relay building and are
conneeted to the sensor by optical fibres. In this case, the
electronics can be considered as those of a relay with the
same requirements in terms of resistance to disturbances
and with equivalent or superior operating reliability. The
case of a seeondary electronics unit in the switchyard or of
digitd electronics at the HV potential is more complicated.
This power supply constraint is a disadvantage compared
with conventional trmvdiormers, but the state of the art in
electronics allows it to be overcome while still meeting the
operating reliability and cost requirements.
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