up voltage in tethers to reduce losses.

[freddecourse]

Hello

I want to have any opinions about this idea. I think to rise up the voltage in the tethers to compensate the losses (150 feet).

12 volts to 120 volts from the surface and the opposite in the rov. Surface can also be a small fuel generator for 120 volts

this one at the surface:

sideview3000.jpg (23.24 KiB) Viewed 2843 times

and this one inside the rov

$(KGrHqN,!pME8WvvHb3CBPPLY,cPdQ~~60_1.jpg (61.88 KiB) Viewed 2843 times

Freddecourse

[SEATIGER]

Are you talking about running AC through the water? High voltage AC through the water is a bad idea. Try getting in the tub and throwing a hairdryer in there.

[shaneb24]

GFI???

[Sterno]

JW Fishers runs 120 volts AC to their towed cameras for lighting through a GFCI box and it seems to work fine as I haven't been electrocuted yet. As long as the cable is properly sealed and you ground your system properly I foresee no problems.

[Never prototype]

Seems like you have a good plan for power. Are you concerned about signal losses in that length? Also will the high voltage ac in the umbilical interfere with your signal? Consider using coax or some other rf shielded wire. With your power system and optical comms you might be able to go a lot deeper too.

[Unorthodox]

or heat from that inverter?

[Joe]

120 volts down the tether should be no problem. Seabotics LBV ROVs use 120v right down the tether. Not to be rude... but electrocution by a hair dryer/toaster being dropped into a bathtub with you in it is a myth. There's no dark magic about 120v electricity and water, it's just another conductor. Yes, you can feel a tingle, but a 2-second encounter won't kill you. This does change as voltage goes up, I'd stay far away from 408/480 single phase in water (or out for that matter)... that could kill anything... As for GFI, I've never known one to trip when it's supposed to. Just my experience though...

Signal integrity may or may not be an issue. Coax cable is always a good idea, but a twisted pair might do the job. AC power (here in the United States) is 60 Hertz. This frequency is too low to interfere with the camera signal, and would cause a minimal interference with any serial communication. The thing to watch would be the converter on the ROV causing high-frequency ripples in the power cable... this could mess up all kinds of signals. Again, using coax should take care of it.

Cool fact: the nerves in your body are literally coax cable! It's really cool.