Trevor,
Thanks so much for the quick reply. I sincerely appreciate the guidance.
For reference, here are the AC specs for the Hioki.
Per your comment, I agree that the Hioki will provide the necessary resolution. Not sure how long it will take to receive the B-Stop, but I am looking forward to trying it out.
Do you have any suggestions for how to go about figuring out whether the time dependent tripping is boat-based or shore-based?
@MeltemiCaz Hi Bill, I dont know how the boat is configured but you mentioned an isolation transformer. If you have an isolation transformer in my view it is very unlikely anything shore side is the probem. I also note the RCD on the input of the boat is ok but an RCD downstream from that is tripping.
I know you want find the time related cause of the tripping and fair enough but when you install the B-Stop the trip margin will increase and that issue may be a thing of the past.
Your leakage current presently has the system very close to the tripping point for the RCD. Changing the RCD may make a change, not because the old RCD has a problem but because the new RCD may have a slightly different trip point than the old one. It may be slightly better or it may be slightly worse.
You could put the meter on minmax on circuits you think may be causing the time related problem but the variation could be quite small to take the leakage past the trip point.
I know you want to find the time related cause but when the B-Stop arrives I am hoping your time related issue will disappear.
@Yachtbird - what has been your experience measuring the mA leakage just before and just after the RCBO? Given the wiring on my panel, accessing the L-N on the input to the RCBO is very easy, but measuring the L-N on the output is hard. Should the results be the same?
@MeltemiCaz yes, the results will be exactly the same.
@MeltemiCaz …. Fantastic Bill……I am so eager to know the results.
I also purchased one of these data loggers. Let’s if it can track the data.
It is supposed to measure:
@MeltemiCaz that data logger looks good but may not have the sensitivity to see any leakage currents. I couldn’t find its lowest level sensitivity but if but active and neutral passed through the sensing core you could hopefully see the imbalance ( leakage).
Anyway, I am keen to hear your report about your trip margin when the B-Stop is installed. If you want to simply do that installation quickly to try it, wire it to a three pin plug and put in to one of your GPOs. You will see the change with the leakage current meter immediately.
No B-Stop, 18.9 mA, Shore power on, inverters in pass-through mode, 251 V, 60 Hz
B-Stop on w/o jumper - 5mA correction, 12.3 mA, shore power on, inverter breakers on, inverter pass through on, MW on, IP43 Charger on, 251 V, 60 Hz
@MeltemiCaz you’ve fixed it! Congratulations and well done. You can relax now. 2025 will be a good year for nuisance tripping!
As it turns out, right after turning the inverters on the mA leakage is lower at 9.68 mA but climbs to 12.3 mA in a few minutes:
No B-Stop, 0.42 mA, Shore power off, innverting mode
B-Stop, 1.26 mA, Shore power on, inverters breakers off, in inverting mode
No B-Stop, 5.51 mA, Shore power on, inverter power breakers on, in the inverting mode
No B-Stop, 18.9 mA, Shore power on, inverters in pass-through mode, 251 V, 60 Hz
B-Stop active, 4.28 mA, Shore power on, inverter breakers on, no pass through, inverting on
B-Stop active, 5.71 mA, Shore power on, inverting, no inverting pass through
B-Stop active, first on the leakage starts at 9.68 mA, shore power on, inverter breakers on, inverter pass through on 251 V, 60 Hz
B-Stop active, settles at 12.3 mA in a few minutes, inverter pass through, MW on, IP43 Charger on
I would to try the B-Stop with the jumper installed to see what the 10 mA correction looks like, but am concerned with the mA leakage correction w/o the inverters in pass-through from the Shore power input.
@MeltemiCaz …great results… The reason the leakage changes when inverting or not inverting is the ground neutral link is active when the Multiplus is inverting. That is so any loads on the output of the inverter can still trip an RCD if you have excessive leakage ( like a person is being electrocuted).
When not inverting the ground neutral ink is opened so the leakage on the loads of the multiplus is passed through to input. That is when you see the leakage increase at the mains RCD.
You now have about 10mA of trip margin as I think your RCD trips at about 22mA. That should be plenty and I doubt if you will see the trips occuring at certain times of day like before.
I really pleased you could resolve it.
@MeltemiCaz I think it looks like it is already in 10mA mode? Im not sure what you meant by [quote=“Bill X., post:33, topic:2375, username:MeltemiCaz”]
but am concerned with the mA leakage correction w/o the inverters in pass-through from the Shore power input.
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Anyway, big improvement. You will always have some leakage as that is simply physics I’m afraid. Well done in improving the trip margin. If it is in the 5mA setting, try the 10mA setting and see it improve even further. Maybe at 60Hz it corrects more than at 50Hz so that is the discrepancy.
Sorry, what I meant to say is that I am only using the B-Stop with 5mA of correction, i.e. the jumper not installed. I was wondering what would happen if I installed the jumper for 10mA of leakage correction when not using the inverter for pass through. Is there an OVER-correction that goes in the opposite direction, past zero and get re-introduced as additive? (not sure that I’m asking this question correctly, but hopefully it makes sense.)
@MeltemiCaz Yes, it will correct the other way but at 10mA it will not trip the RCD. Your thought process is perfectly valid. That is why you wouldn’t put two B-Stops in parallel with 10mA correction because when all breakers are off it may make the RCD trip with 20mA of correction the other way.
I will test the B-Stop tomorrow with the jumper installed. Thanks for the support. I will also install the data logger later this week. I’d like to be able to record the promised electrical parameters: active power and energy, reactive power and energy, power factor, RMS voltage, RMS main current, RMS leakage current.
Nice work Bill. I think you have nailed it and you now have a very good understanding of your electrical system, that is for sure. It is good to be able to have a plausible story for what is happening and better still to have a remedy based on some solid engineering. I’m glad the device has improved your trip margin and great that you are keen enough to actually measure the difference with a meter and see the difference with your own eyes.
None of this is rocket science but it does take some effort to understand what is happening.
@Trevor Thanks, I really appreciate the help and sound advice. While I still don’t know the reason behind the time-based RCD tipping, I do feel that I will eventually figure it out.
Thanks again!
