Protective system for capacitive voltage transformers including a circuit for t{d fh-coupling

Claim 1

In a capacitive voltage transformer arrangement the combination comprising at least three capacity voltage divider sections connected in series, circuit means connecting one end of said series connected capacity sections to a high voltage line, circuit means including a drainage coil connecting the other end of said series connected capacity sections to ground, a feed-in connection for coupling high frequency signals to said high voltage line on said capacitive divider between said drainage coil and the adjacent capacity divider section, a transformer having its primary winding connected across an intermediately located capacity section in said series, a compensation choke coil connected in the circuit extending between one end of said primary winding and said intermediately located capacity section, a low-ohmic HF blocking coil connected in the circuit extending between the other end of said primary winding and said intermediately located capacity section to adapt said transformer arrangement for carrier coupling, said transformer including a secondary winding for connection to a desired load and a tertiary winding connected at one end thereof to said other end of said primary winding for producing a comparison voltage, means tapping from said capacity voltage divider a voltage which during normal operation only of said transformer is substantially equal in amplitude and phase with said comparison voltage, means for producing a difference voltage equal to the difference between said two voltages, and switching means responsive to said difference voltage for switching in a damping burden on said transformer thereby to protect said transformer against undesired oscillation effects.