| 摘要 |
In the case of inductive rail contacts there is the problem that the receiving devices of this equipment can be so strongly influenced by the traction current flowing in the rails that their functional capability is not always ensured. Thus, in addition to high-frequency influencing, in particular by contact line circuits, low-frequency influencing of the track equipment by means of traction currents also takes place. In this case, the traction currents magnetise the rail material periodically and thus bring about a change in the permeability of the rails. Since a large portion of the magnetic field lines which originate from the transmitting devices of a rail contact and influence the receiving devices is conducted in the rails, consequently a periodic change in the voltages induced in the receiving devices of the rail contact takes place, which change can simulate response of the rail contact and, however, at least leads to a reduction in the response sensitivity. The invention provides for a layer (5) which is made of material with poor magnetic conductivity and fits tightly against the travel rail to be arranged between travel rail (1) and receiving device (31, 32) which layer (5) covers the travel rail from the underside of the rail head to the outer edge of the rail foot. As a result of the formation of eddy current, this layer leads to an extensive field displacement that is to say the influencing of the rail contact being reduced when the track is clear. Thus, the influence of the traction current on the receiving device is also reduced. The voltage induced in the receiving device does not suddenly jump to a value which is sufficient for triggering a reaction until the rail contact is travelled over.
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