Page 156 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

144 CHAPTER 7 Power and Telemetry
Table 7.1 System Components by Vehicle Size
Component OCROV MSROV WCROV
Lights
Cameras Thrusters Manipulators Transformer TMS
Hydraulic pump LARS (see note) Electronics Vehicle sensors Payload sensors Tooling
X
X
X [optional]
[optional]
[optional] X
X [optional] [optional]
X X
X X
X X [optional] X [optional] X [optional] [optional] [optional] X
X X
X X
X X [optional] [optional] [optional] [optional]
with the power-hungry component requirements dramatically increasing the vehicle’s size and power budget. OCROVs require cameras, lights, and low-power thrusters, all powered through short lengths of small gauge (typically), low-voltage conductors. All deepwater vehicles require high-voltage transfer systems (typically AC for long-distance conduction) with several electrical and mechanical converters at the tether management system (TMS)/vehicle combination. Some common components requiring power (note: electric power drives both the electrical components directly as well as the mechanical pump to drive the hydraulic components) are listed in Table 7.1 by size class. Note: there are a few fully electric WCROVs (i.e., no hydraulic components on the vehicle), but the vast majority is hydraulic; therefore, only hydraulic WCROVs are considered here. Also, the LARS is typically on its own power circuit.
7.1.3 Power system arrangements
The general arrangement of an ROV power delivery system is designed to comply with the full vehicle power required at the initial junction box (J-Box) on the vehicle (i.e., where the power first arrives at the vehicle). Should there be a TMS upstream of the vehicle, those requirements are added to the power budget demand. From that point, power is converted and then sent to separate “bus” circuits to provide the necessary power to various components and conditioned to the appro- priate parameters (e.g., AC or DC, single- or multi-phase, sinusoidal or square wave, nominal volt- age). Power is split into high-voltage (HV) and low-voltage (LV) circuits for driving the high- demand items with the HV power, while lowering the voltage (and rectifying to DC) for the sensors and electronics. The power can be converted on the surface, at the TMS, or on the vehicle itself before distributing to the various bus circuits, depending upon the configuration of the system. Lights, for instance, may be powered via a DC or AC source depending upon the vehicle power available. Cameras and sensors are typically DC-powered while hydraulic pumps, thrusters, and camera pan and tilt (P&T) units can be either AC or DC (but will certainly be on an HV circuit).