The Topside Power Supply Unit is a component of the Outland Technology Power Supply (OTPS). It converts 100-240 VAC power to 400 VDC power for transmission through the tether. It’s designed with an emphasis on safety, including a LIM/GFI safety circuit. With a built-in Fathom-X tether interface board, laptop charging outlet, and a laptop shelf, it’s more than just a power supply!
The power supply is built into a rugged hardshell case that’s easy to transport. It’s designed to be operated with the lid open to provide airflow for cooling and to act as a topside control station for the ROV pilot. The middle section has a laptop shelf so that you can operate from a single tabletop. Next to the laptop shelf at the top left is the tether input connector, a Binder 696 Series. It’s rated for high voltages and has concealed pins for safety. Next to that is a ground wire connector. The unit comes with a ground wire that should be attached to the nearest earth ground for safety.
Below that is the input power cable that plugs into a normal 100-240 VAC wall outlet. The unit comes with a North American plug (NEMA 5-15) and can be used with a plug adapter to operate with other common plug types. Next to the input power cable is an auxiliary power outlet to plug in your laptop charger during operation. The auxiliary power plug is compatible with several different plugs and doesn’t generally need an adapter. A power switch allows you to power the unit on and off at any time. That switch also power cycles the ROV but doesn’t disconnect power to the auxiliary outlet.
The inside of the power supply unit is off limits to users for safety reasons, but there is a dedicated user-accessible area on the top of the unit. Inside is a Fathom-X tether interface board, and a USB to Ethernet adapter that replaces the FXTI that is usually used to connect to the ROV. No FXTI is needed when operating with the power supply unit. There’s also access to a spare twisted pair from the tether that can be used to communicated with payloads like a sonar.
Closest to the user is the most important part of the power supply unit, the GFI safety test feature and status screen. The ground fault interruptor (GFI) is also commonly known to ROV users as a line insulation monitor (LIM). It detects any current leakage on the high-side or low-side of the isolated power supplies and automatically shuts off the outputs if an unsafe level of current leakage is detected. It’s designed to comply with the guidelines of the IMCA Code of Practice for the Safe Use of Electricity Under Water. The test switch toggles up and down to test high and low-side leakage.
The status display indicates the health of the power supply unit, the voltage and current output levels, and the history of any GFI faults.