| 摘要 |
<p>A subsea system comprises a multiplicity of subsea installations (M-1..M-n) and a common transmission line (2a) in an umbilical for the conveyance of power or data communication electrical signals to the subsea installations. The system provides on the common transmission line a plurality of safety signals (T-1..T-n) in the form of tones separate in frequency from each other and the other signals on the line. Each subsea installation is arranged to receive from the common transmission line selectively a respective one of the safety signals for the control of a fail-safe device (9) in the installation.</p> |
