With recent trends toward more environmental regulations and energy consciousness on the part of end users, vehicular rotating electric machines are being required to offer high output and high efficiency and improvements are proposed on stators that produce a particularly great effect.
In general, a stator used in a rotating electric machine includes a stator core and a stator winding. The stator core has a plurality of slots arrayed circumferentially and opening in an inner peripheral surface. The stator winding is formed of a continuous wire into a wave. A winding pitch of an annular coil used for the stator winding is a full-pitch winding and the stator winding is inserted in each slot across a plurality of teeth. A rotor includes a pair of rotor cores having claw-shapedto a first AC transmission network, a second converter station connected to a second AC transmission network and at least two conductors connecting the first and second converter station. Each converter station contains a grounding point connected to a ground electrode for making electric contact with earth. Thus the ground conductor comprises the ground electrode at each converter station and the ground between the two ground electrodes.
A bipolar HVDC transmission system conventially comprises a pair of overhead conductors carried by a plurality of towers from the first converter station to the second converter station. The conductors are suspended in isolators from arms of the towers. Each tower also caries shield conductors for protection of thunder lightning. Commonly the distance between two adjacent towers is around 400 m. Each