User manual

OceanWorks International
120 – 6741 Cariboo Road
Burnaby, BC V3N 4A3
Canada
www.oceanworks.com
Document Number: 0848-RPT002 Subsea System User Manual
Author: Graham Cunliffe Page 10 of 27 Revision 1.0
Do not apply power to the JB unless it is electrically bonded to the power supply chassis. This
ensures that there is no potential between the JB chassis and earth ground. This bonding
protects personnel who are either floating with respect to earth or bonded to earth via ESD
measures. This bonding can be achieved by connecting the JB to earth ground with a
#8AWG or larger wire. Using a large gauge wire simulates the deployed environment of the
JB where the resistance seen between the earth reference point of all devices approaches
0Ω. The holes in the pressure vessel can heads used to fasten the can head mounting jig are
an ideal bonding point for the JB. OceanWorks strongly recommends that earth bonding of
the JB is standard procedure whenever the JB is powered outside of seawater.
3.3. Command Interface
The command interface to the subsea software is achieved via TELNET. For more
information refer to the Junction Box Telnet Command Manual.
3.4. Data Handling Interface
Telemetry data is transmitted from the subsea system as a UDP data stream. Refer to
Appendix A where the UDP data structure is defined.
4. Recovery Procedure
When recovering the JB, first ensure that the JB is not powered. Once this has been
established the ODI ROV cable can be disconnected. Before disconnecting instrument
cables, dry the JB can head so that there is no liquid present on or around the SeaCon
connectors. Compressed air or a heater can be used to make sure that all liquid is removed.
If the JB is to be opened, follow the same procedure as with the SeaCon cables to make sure
that no liquid enters the pressure vessel. The NEPTUNE Assembly Alignment Fixture, part
number 0848-250-T20000, should be used when opening the JB to make sure that
components of the pressure vessel are not damaged.
5. Junction Box Operational Modes and Procedures
5.1. Power ON/OFF and Initiation of Software
When the JB is powered up all of the breakers enter a safe state (output disabled) and the
control computer automatically boots the subsea software. A 60 second lockout is imposed
on the breakers so that they cannot be switched on before their input Negative Time
Constant (NTC) thermistors have returned to their high impedance value. This protects the
breakers in the case of a rail crash, i.e. if the JB looses power from the MVC with breakers
on, the breakers cannot be switched back on before it is safe to do so without causing
damage.
Once the subsea software has booted, telemetry data is sent via the UDP data stream.