Volt/Amp meter + Grounding Probe

[christopher.issler]

I'm working on building a probe that achieves the following goals, possibly some are outside the current scope or capabilities of the software, but it's nice to hope...

1. Grounds the tank using a titanium probe to ground, to suppress any EMF created or stray voltage that made it's way into the tank by damaged or worn equipment.
2. Measure the Amps and Volts across the ground probe to the ground.
3. Leveraging the 0-10v inputs, measure the amount of amps/volts across the line. Perform the following...
A. If amps/volts are too high, based on static boundaries, alert the user via notification.
B. Trend volts/amps, abnormal increases compared to normal trends, send notification.
C. (A dream)Have a diagnostic tool, which completely powers down all devices, looping from this point on, pause 5seconds, then power each device for 30seconds, and sequentially powers up each device. To try to identify a piece of hardware which was is causing increased amp/volt spikes. Measurements are logged ever 5 seconds and logged in an output screen.

Some assumptions.
1. This device and capability in no way is intended to replace a GFI.
2. A single grounding probe should be able to be connected to each tank/body of water where a heater/pump is submerged.
3. The panel is not neutrally grounded.
4. The ground lug on an XP8 is not monitored currently in anyway. If it is, a probe to the 0-10v could be used and grounding could be done on the 110v ground leg on a Xp8

 

[Don]

There are some interesting ideas here. The biggest issue though is that the leakage currents involved are very small. 5 mA will cause a GFCI to trip. So anything above 5 mA is irrelevent. But measuring currents that are typically below 1 mA is going to be virtually impossible with just a 0-10V input. It would certainly require some active amplifiers. In real life, the leakage currents encountered are well below 1 mA, usually in the range of 100 uA or less.

 

[christopher.issler]

There are some interesting ideas here. The biggest issue though is that the leakage currents involved are very small. 5 mA will cause a GFCI to trip. So anything above 5 mA is irrelevent. But measuring currents that are typically below 1 mA is going to be virtually impossible with just a 0-10V input. It would certainly require some active amplifiers. In real life, the leakage currents encountered are well below 1 mA, usually in the range of 100 uA or less.

Isnt measuring the voltage and amperage a combination that could/should be measured? 1mA@110Vac is substantial isn't it? Or even 50Vac? Or is measuring voltage even possible? These leaks may not be irritating to humans, but to corals that's got to be detectable or at the least be detrimental to them.

 

[Don]

The problem with measuring voltage is that there generally isn't any. Consider that you are measuring the voltage between a ground probe in the water and the electrical system ground. That is a very low resistance connection, should be much less than 1 ohm. Assuming 1 volt across 1 ohm. That would indicate a 1 Amp current flow. But the GFI would have shut the circuit down at 5 mA. So this means the highest voltage we can see is 5 mV (assuming 1 ohm, in reality 0.1 ohm is more realistic. If there is any voltage in this path it will result in a current which will trip the GFCI.

Now the leakage current is something that could be measured. But it wouldn't be with somehing as crude as a 0-10V input. It would require something pretty much equivalent to a multimeter.

 

[christopher.issler]

The problem with measuring voltage is that there generally isn't any. Consider that you are measuring the voltage between a ground probe in the water and the electrical system ground. That is a very low resistance connection, should be much less than 1 ohm. Assuming 1 volt across 1 ohm. That would indicate a 1 Amp current flow. But the GFI would have shut the circuit down at 5 mA. So this means the highest voltage we can see is 5 mV (assuming 1 ohm, in reality 0.1 ohm is more realistic. If there is any voltage in this path it will result in a current which will trip the GFCI.

Now the leakage current is something that could be measured. But it wouldn't be with somehing as crude as a 0-10V input. It would require something pretty much equivalent to a multimeter.

And that's what I'm suggesting as a module that can be added to the series of add-ons.