Monitoring of Rack Phase Difference during Jacking Operations

GSF Galaxy III Jack-up

Monitoring of rack phase difference during jacking operations can give an early indication of possible leg over-stresses. Taking continual manual rack phase measurements during jacking operations is both difficult and labour intensive. The Monitor Systems Engineering rack phase differential monitoring system provides an accurate electronic / mechanical system for measuring and recording the rack phase difference of each leg.

The rack pitch differential monitoring system is based around the Siemens S7-300 PLC. The S7-300 Series PLC provides high level control functions, programme structuring, networking and software integration.

The main user interface is via a 15” Industrial Panel PC running Windows XP Professional and WinCC Flexible Runtime Scada package. This interface will display all RPD information graphically and numerically as well as displaying all alarm information, historical trending data and maintenance procedures. Three 8” remote mobile hand held HMI’s are also provided. The mobile HMI’s can be connected to Connection Points at each leg chord to display RPD information to the operator whilst operating the legs from the Remote Jacking Control Stations.

As well as RPD information the RPD Monitoring System also tracks the position of each leg and in doing so can perform calculations to monitor such variables as Leg Penetration, Distance to Tag Bottom and Total Draft. These additional calculations will be based upon manually entered data such as Air Gap and Tidal Water Depth.

All RPD alarms are fully configurable and the alarm levels can be set by the operator. If any alarms are generated an internal buzzer / beacon located on the PLC Station will be triggered.