Measuring voltage in water

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Littlemermaid2019
Posts: 3
Joined: Wed Jan 23, 2019 12:01 am

Measuring voltage in water

Post by Littlemermaid2019 » Wed Apr 03, 2019 10:36 am

So we are able to measure a voltage in the water when we submerge our thrusters. The measurement is done by putting one pole of the multimeter in the water and the other to ground of the powersource. The thrusters themselves are from Bluerobtics so they are factory sealed. Is this a violation of the mate rules, will it pass inspection? The only rule we where able to find is [ELEC - 017E] which doesn't really tell us anything about this.

Best Regards
Little Mermaid

Matthew Gardner
Posts: 987
Joined: Sat Jan 05, 2013 11:19 pm

Re: Measuring voltage in water

Post by Matthew Gardner » Wed Apr 10, 2019 5:08 pm

A properly sealed motor should not do that. I talked with one of our lead safety inspectors and we concluded that this is likely a bad thruster - it did not get sealed properly.

I would recommend talking to Rusti / Blue Robotics folks about this and getting a new thruster. Having a motor that is not sealed would 1) not pass safety inspection and 2) will not work with our power supplies (if something on the ROV is not properly waterproofed, it shuts down the power supply and your ROV goes non-operational).

Good luck.

Matthew Gardner
MATE ROV Competition

Littlemermaid2019
Posts: 3
Joined: Wed Jan 23, 2019 12:01 am

Re: Measuring voltage in water

Post by Littlemermaid2019 » Wed Apr 24, 2019 2:44 am

Hi Matthew,

How do you measure a voltage leak at the competition?
Just so we do the test correctly.

What kind of PSU do we have to use at the competition?

Best regards
Team Little Mermaid

Matthew Gardner
Posts: 987
Joined: Sat Jan 05, 2013 11:19 pm

Re: Measuring voltage in water

Post by Matthew Gardner » Fri Apr 26, 2019 11:50 am

The EXPLORER team power supply is a Meanwell RSP-2000-48. Connected to 115V, it is derated to 1700 watts (35 amps).
https://www.mouser.com/datasheet/2/260/ ... 109673.pdf


RANGER team power supplies will most likely be PowerWerx supplies: https://seamate.org/collections/power-r ... utlet-gfci


I am not sure about measuring voltage leaks at the competition. Safety inspections are done in air and unpowered. So an non-waterproofed motor may get by safety inspection if it appears to be waterproofed from a visual inspection. As many teams use Blue Robotics thrusters, our judges are not going to make you do any tests to ensure they are waterproof. However, I do know that if a electrical system is not properly waterproofed and "leaking" electrons to the pool, the power supplies shut down. My best recommendation is to make sure all your systems are fully waterproofed.

Matthew Gardner
MATE ROV Competition

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