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(11) | EP 2 565 884 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | High voltage coil |
| (57) The invention deals with an HV voltage coil which is an element of a voltage transformer
used in a combined instrument transformer applicable in high voltage electric power
measuring systems. The voltage coil comprises a magnetic core (16), a primary winding
(13) wound onto a secondary winding (14) and surrounded by an upper screen (17), a
bushing of a high voltage instrument transformer in the form of a conducting rod (21)
placed in insulating material (23) with equipotential screens (25), the primary winding
together with the upper screen being located in the coil insulation (24) which is
covered by an external screen (26). The voltage coil according to the invention is
characterized in that the upper screen (17) has the shape of a ring with a gap (18),
which is integrated with a connecting element (19) in the form of a truncated cone.
This base of the cone which has the larger diameter is situated on the external surface
of the ring, and the cone has an axial opening (20) into which a threaded end of the
conducting rod (21) is screwed. Equipotential screens (25) are situated centrically
around the rod (21) and they have overlapping longitudinal edges which do not touch
one another in any point. A copper tape (27) is wound on the insulation (23) and on
the external screen (26) of the voltage coil.
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