Power & Video OFJB
The Fathom Systems Power & Video oil filled junction box (OFJB) complements the iVP product range by providing a ‘step down’ power supply interface to the control system from the host supply.
In a typical scenario, the umbilical will power the iVP system via a pair of power conductors that may carry a 30V DC power supply from the surface to the underwater OFJB. Inside the OFJB is a pressure-tolerant 150W DC-DC converter module that converts the DC power from the surface to a regulated 5A 24V DC supply for the iVP. In addition, line balance Video Baluns will also be fitted providing a 3 24v DC Camera & Video inputs, typically using a Wetcon 4 Pin bulkhead interface. The interface to the main umbilical is typically a Wetcon 16 pin wet-mateable connector. The OFJB remains flexible in that other manufacturer’s electrical bulkhead connectors may also be fitted.
As the load current of the iVP varies depending on the number of valves energised, there will be some fluctuation in the voltage emerging from the umbilical at the OFJB. By using a ‘wide input’ DC-DC converter, the supply fluctuations will be overcome, and the output supply to the iVP will be a constant regulated 24V DC. The maximum voltage of 30V DC at the surface is selected to avoid the requirement of a Line Insulation Monitor to protect the Divers (based on the limits set in the AODC regulations).