Ship switchboard earth fault

Greetings. Any ship ETO here? I have problem with my ship switchboard 380v earth fault. I can’t find the source also i switch off all 380 brakers still indicates fault. And there’s no trip all machinery are working properly.

The upper left 3 indicator lamps appear to show no ground indication. When there is a ground or earth fault, usually one lamp will be dim or extinguished and the other two will be brighter.

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I’m with @injunear, the indicator lights should be indicating a ground on one of the phases if there is indeed an earth fault. Below the megohmeter is a button that shows “Earth Test”. Is it possible that this is stuck in or has failed?

Yeah i already try to test with the lamps, to my surprise there is no any dimmines or off. The lamp stay the same.

Is that a Bender ground fault detector? Does it start with a high IR then slowly move to a fault level?

Yeah it starts with high and stays there.

High resistance is the opposite of a fault, your meter is showing low insulation resistance.

Is it a Bender meter?

Yeah it’s a bender meter.

Do you have any large tubular element resistance heaters online?

Several years ago I had some issues with the Bender system displaying phantom grounds due to the way Bender detects a fault. The heaters were practically infinite resistance to ground but Bender thought otherwise. The system doesn’t directly measure a fault, it (in my own version of how it works) injects a signal onto the circuit and “listens” for an echo.

It created a great deal of problems because even after having two independent electrical contractors confirm the heaters were not the issue and Bender stating they had the same issue with some German Army water heaters (and never found a reason for the issue) we installed a separate independent detector that actually measured fault current … it displayed no ground faults.

If you don’t have any heaters then sorry, can’t help with that one other than offer that I am very skeptical of Bender’s detection strategy. BTW the offending system was the IRDH275 and we had the same problem on two different boats.

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Currently i don’t have any online heater. Any i appreciate the help.

Sorry I couldn’t help. Please keep us posted on your troubleshooting efforts and (hopefully) the source and solution.

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Thank you steamer. I will post if there is any update.

I’ve never seen this Bender system. Interesting. I always had to rely on the megger.

This could be split off into a new thread with steamer’s post on ground fault detector theory.

1)I’ve always wondered how the various manufacturers do online ground fault resistance measurement (online “megering”) and what the pros/cons are to each method

2)try as I may, I never found good information best practices to improve efficiency in chasing down ground faults on consumer boards. Having chased faults in massive passenger ships the old fashioned way of shutting off loads one-by-one, there must be a better way.

3)is there a portable meter that can check ground faults online? Versus de-energizing and using traditional meggar

4)on large passenger ships, don’t you think it is stupid to run non critical systems with “floating ground”? Why do passenger cabins need floating grounds? Do it like shore….if there is a shirt to ground, the breaker trips due to overload. Circuit shuts off and issue gets repaired immediately.

If you don’t have a spare meter on board, do you have another meter in service on another switchboard? Perhaps switch out the meter to see if the problem follows it?

I just recalled buying two of the independent ground fault detectors I mentioned in my earlier post and found the unused second one. In case anyone is interested, it is an inexpensive Littlefuse EL3100-00 Ground Fault & Phase Voltage Indicator 208-600 Vac 50/60Hz

I just installed it across three easily accessed phase conductors so that it monitored the entire bus.

With regard to using a Megger, unless I can totally isolate any equipment that is not documented as or inherently “megger safe” I am really leery of applying 5 or 600 or a thousand volts to the supply. Too many voltage sensitive semiconductors in stuff these days to risk it.

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Is it mounted across the line or do you use instrument transformers?

Is the output ground fault indication or insulation resistance/condition?

Looks like he has done all the normal tracing. Bender systems like most systems need replacing every couple of decades. Though passive, heat and vibration takes a toll.

Connected directly to phase, no transformers just fuses. It has fault and phase lights plus relays for alarms.
Now that I have found the other unit I might put it in a case of some sort and use it as a portable tester.

https://www.littelfuse.com/media?resourcetype=product-manuals&itemid=abc864f9-e44c-4672-8af0-3e0ecfd90fa4&filename=el3100-manual

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I hate chasing grounds! Whenever I find a Bender on the switchboard I cringe and warn the chief that we might end up chasing phantom grounds that are guaranteed to drive everyone crazy with finger pointing and head scratching.

The first time this happened to me it took weeks of chasing and no end of demonstrations to finally discover it was the detector itself and of course Bender was no help until one of their techs in Germany admitted knowing about the issue in an email.

I am not implying that the same situation applies to the OP and the Bender is the problem but I am saying it can make fault chasing a royal pain in the stern if simple circuit breaking doesn’t show anything.

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