What is the deepest that anyone has tried to operate one of these thrusters? Has anyone done a pressure test with the motor running down to 4000 msw? I see some older posts from 2015 indicating that there were test results for 3000msw, but they hadn’t been shared yet… wondering if anyone / Blue Robotics has in-sites into what might fail, or recent testing results?
I’m also curious about long duration immersion. Looks like 316(?) stainless construction. Worried that might not last long enough. Has anyone tried to immerse one of these motors in dielectric fluid?
I have an application where I need to run an ROV thruster at 4000 msw for a couple weeks, but dont have time to source a custom designed thruster from a major manufacturer.
I’m thinking about modifying the thruster to put the motor in a dielectric fluid for corrosion resistance, and putting the shaft through a dynamic seal to interface with an impeller. Dont need the full performance of the thruster so might be able to live with the losses.
While we haven’t conducted testing at those depths directly, it should be possible to use at that depth for indefinite duration without any issues.
The important thing that must be done to operate deeper than the rated depth is adding a connector to the cable going to the thruster (like one from BlueTrails Engineering, which also sells the T200 with connector already attached.) The likely failure mode below 300m is water finding its way past the potting compound that seals the end of the cable to the stator windings, and if using a WetLink Penetrator, this water can pass thru the cable and into your housing!
A connector stops this, but may lead to some voltage “leaking” to the water, which can impact performance slightly and reduce efficiency - far less than some sort of housing filled with oil would! Since the T200 is fully flooded, the modification you describe isn’t really going to be possible, but perhaps the M200 could be used to accompish something like that? We’ve had users operate at 1000m for 1.5 years + off the coast of Monterrey bay. We heard an update on this in the last of the StreamFest episodes!
I’m curious why 316 Stainless Steel wouldn’t last long in your application? Typically it’s one of the best materials for corrosion resistance….
I’d argue that Blue Robotics can be considered “major” as there are over 6000 BlueROV2s in the world, and likely more T200s than any other subsea thruster type ever made in existence!
To add to what @tony-white said, when adding a connector to the end of the cable, you can choose between a field overmold or a factory overmold. Based on experience, I would certainly recommend a factory overmold from a company like Subconn. A factory overmold means that they actually manufacture the connector from scratch with your cable so that the connector and cable are essentially a single piece of neoprene. A field overmold uses a mold with potting compound to splice a connector to the cable. While the current iteration of our 900m ROV has lasted 1.5 years with field overmolded connectors, there would be a higher degree of confidence in the system if it had factory overmolded. We recently had 16 T500’s factory overmolded for our next upgrade. It was not cheap and had a several month lead time.