| 摘要 |
<p>PCT No. PCT/SE83/00023 Sec. 371 Date Sep. 30, 1983 Sec. 102(e) Date Sep. 30, 1983 PCT Filed Jan. 26, 1983 PCT Pub. No. WO83/02860 PCT Pub. Date Aug. 18, 1983.The invention relates to a method and an apparatus for secure interruption of the supply of electric power from e.g. a low-frequency source (1) to a signal lamp (2) which when alight announces permission for a train to pass. The output voltage (a) of the source (1) is chopped by a chopper device (4) to a high-frequency alternating voltage (e,f) in response to a high-frequency input signal (b) to the chopper device (4) and is transferred from the primary to the secondary side of a transformer (5,6) as well as being rectified and filtered to form a voltage (k) applied to the signal lamp (2), said voltage (k) having a wave form corresponding to the wave form of the output voltage (a) of the source (1) and which is securely interrupted by interrupting the input signal (b) to the chopper device (4).</p> |
