We’ve begun building up our BlueROV2 and we are definitely excited about the build. I know that there had been a previous discussion back in May 2016 about power over tether, but I was hoping to re-open that discussion.
We aren’t looking for particularly long tether power…I’m just hoping we can work supply power town the tether on the one of the spare twisted pairs so that we can work longer with the vehicle and possibly push a longer tether length of about 200-meters or so.
My thoughts were to supply between 48 VDC and 120 VDC down a twisted pair and then use DC-DC converters on the bottom end to bring the supply to 15 VDC. There are concerns about this:
- Spec on the subsea wattage necessary for the system when it is running 6 thrusters and 4 LEDs.
- Heat in the tether.
- EMI in the tether or in the subsea end.
- Heat at the subsea DC-DC converters and managing that.
We can manage #4 by replacing the battery can with an aluminum housing and properly heat-sinking the converter there. And, based on what we’ve seen with other systems, their shouldn’t be a noise issue in the tether caused by the power riding near the Fathom-X twisted pair. I am worried about the subsea wattage, the possible heat in the tether (to supply that wattage) and the EMI from the DC-DC converter.
Does anyone have any thoughts on this? Or should we be leaning more towards the approach that Patrick Rowe took, to which @tciii referred, using 3-phase AC power?