In the corona discharge test, the remote module of the
transducer system is on the high-voltage side, and sometimes,
the applied voltage may be up to 1000 kV, i.e., it is working in
a serious electromagnetic environment. At the same time, the
electromagnetic fields of the corona discharge can affect the
performance of the remote unit of an optical current transducer,
despite some antiinterference methods being taken.
In the design of a measuring device that is used in a serious
electromagnetic environment, the electromagnetic shield is a
common method. This paper does not make any exception.
The material of the shielded box for the remote module of the
transducer is an 8-mm-thick copper.
To obtain the idea performance, the round plane of the
circuitry in the high-voltage side is connected to the shielded
copper box, which is connected to the high-voltage source. A
coaxial shielded cable is used as the input and output signal
wires for the remote module. The shielded layer of the cable is
connected to the copper box. More care should be taken with
the connection between the cable and the resistor to reduce
connection inductance.
Finally, in the field test, the shielded remote module of the
transducer is placed inside the corona-free, high-voltage input
wire (see Fig. 7), and the shielded box and the ground of
the circuitry are in the same potential (both be connected to
the high-voltage source), and this can further reduce the interference
to the remote module, which is caused by the outside
gas discharge. With these methods, the reliability of the transducer
can further be improved.