| 摘要 |
<p>The present invention relates to a sensor unit (101) for activation based on the presence of a voltage in a cable (103) comprising at least two conductors (109) for conducting current. The sensor unit comprises at least two sensor electrodes (402, 403, 502-504) detecting an electrical field by measuring a voltage difference between them, attachment means (107) for attaching the sensor unit and thereby the sensor electrodes at different positions around the cable and a communication device (209) for wirelessly communicating a signal based on the electrical field. The unit can be mounted externally on existing cables and communicate to external devices whether there is power in the cable. E.g. the unit can communicate power interruption or power changes. The communication device is only activated when necessary thereby using very little power.</p> |
