| 摘要 |
The present invention relates to a safety device for use in a street lamp, comprising: first means for connecting to a power grid (5), second means for connecting to at least two external units (3,4), a first one (3) of said two units being adapted to draw current and a second one (4) of said two units being adapted to generate a potential difference, and further comprising a switch (6) adapted to switch between a first position, in which said first unit (3) is connected to said power line (5) to draw current from said line, and a second position, in which said second unit (4) is connected to said power line to apply said potential difference to wires of said line; and a communication system adapted to detect the presence of a safety signal on said power line and to switch said switch (6) to said first position in the event that said safety signal is missing or faulty. |
