An Odd ATS Situation…

For those who’ve been following, here’s a 04 July Update:

Upon my initial bonding check (recall, this a few days back at the main panel…), I’d discovered that several neutrals were in fact bonded at grounding bar..Honestly, this confused me a bit (what is the actual source of this bonding, and are there any reversed wires??), so I began a deeper examination…

I figured I’d start at the main with a goal of ending up with a good, cogent circuit diagram, but due to some missing circuit labels, I found it extremely difficult to visually trace, or determine one wire from another because of what was a congested birds-nest of wiring…So I’d have no other choice but to unravel this ugly birds-nest, but once disturbed I knew I’d not be able totally recall the original wiring layout - but no matter (lol!) because I intended to start out fresh…

So I began disconnecting everything and pulled all the wiring free and into the open light of day in order to identify, meter-test, and affirm each individual circuit…Concurrently, I also set out on a bottom-up approach, starting at the 30amp entrance to test each circuit at each end… This all ended up a several day project (involving two retrofitted sub-panels, one pre-existing ATS switch and one new), but I finished up by sketching a rough but extremely valuable schematic…

Armed with a bunch of new knowledge, I finished-up today by doing a camper-wide reconnect and ensuring that each circuit was working as was intended.

In the end (luckly!) I was able to resolve a few issues as follows:

First off, turns out that the source of the continuity meter’s previously mentioned ‘raspy tone’ was/is being caused by the pass-thru inverter’s floating ground - when shore power is disconnected, inverter ground and neutral become bonded, meter tone is quite normal and pleasant, but once connected to shore power (i.e. pass-thru inverter unbonded…) the tone becomes raspy and distorted, indicating the possibility of a ongoing ‘partial’ floating ground condition (??), and the ugly possibility of nagging ‘eddy-currents’…However, post-mortem this nuance seems to have had no adverse effect on what had heretofore (pre-review) been the fussy ATS relay, as time after time the relay now actuates properly to the inverter’s output…

Secondly, I can’t say with complete confidence what had originally caused the new ATS contactor-relay’s refusal to actuate via inverter power (yet work fine via shore power - huh!!), but post-examination (circuit tear-apart, end-to-end evaluation, reconnect…) all now checks out perfectly (Yea!!)…So it appears that whatever the dang glitch that was preventing the relay from working it’s magic has now thankfully been sorted-out and laid to rest !! Thanks to some perseverance, Objective Met :)

Many Thanks to all those who responded!!

3 tons

3 tons wrote:
Will do, but upon further examination, I’m finding some neutrals in the main tied to the ground bar, while some other neutrals are not tied to the neutral bar…Looks like in someway the ATS relay coil was able to sense this defect, yet WOULD operate (via the inverter) IF I ran the jumper from the ATS’s gen neutral terminal to chassis ground…

Perpays a prior owners handywork. This should be corrected, grounds to ground, neutrals to isolated neutral bar. Then with shore GFCI for the rig power cord it should not trip with loads on each circuit. Nor should any rig GFCIs trip. BTW This is the best way to detect a ground fault as a GFCI trips on 5ma of current.

Possibly this causes the inverter to produce some abnormal power that makes the ATS electronics unhappy.

Today’s morning Update: So in spite of the aforementioned ‘distorted but continuous’ continuity meter tone (when testing inverter output neutral to chassis), if I connect the inverter directly and solely to the ATS relay, the relay becomes operable in fine order… Recall that up to this point the inverter (as previously wired through the elect system and with a distorted meter tone) would not activate the ATS relay…

So I’m also tending to believe that the cause of the distorted continuity meter tone (inverter neutral to chassis) is related to the inverter’s floating ground, but this time around (with respect to previous checks, in spite of this distorted tone), the relay became active…

Lots still to ferret out…

3 tons

FWIW, On Bonding, Per the Prosine manual:

“AC Output Neutral-to-Ground Bonding System,

The PROsine provides an installer-defeatable system that automatically connects the neutral conductor of the inverter AC output circuit to safety ground (“bonding” it) during inverter operation, and disconnects it (“un-bonding” it) when the PROsine has connected to AC shorepower. This system is designed to conform to installation codes that require single-phase AC sources such as inverters and generators to have their neutral conductors tied to ground in the same way that the neutral conductor from the utility is tied to ground.
These same codes specify that the neutral can only be connected to ground in one place at any one time. Any AC source feeding the PROsine is required to have its neutral already connected to ground. Therefore, to keep from connecting the neutral to ground in a second place, the PROsine transfer relay breaks its own neutral ground connection when connected to shorepower….”

Upon edit, the ‘installer-defeatable system’ option mentioned in the first paragraph above does not exist…So much for manuals…

3 tons

Update, with inverter OFF - inverter is a pass-thru type w/ built-in ATS:

Shore power entrance parallels to go to the main and to pass-thru inverter - entrance wiring reveals no bonding…For reference, the Inverter is fit uber tightly beneath the dinette, while it’s input / output J-box resides down below in the aft basement area…

Inverter 120vac output receptacle shows completely normal per plug-in LED tester - note the inverter is OFF.
Neutral ‘corded wire run’ between inverter output and basement J-box (a male to female plug-in corded affair) shows no bonding ‘when unplugged from inverter’ - However, if I mate together the inverter’s two corded output connectors, the continuity meter indicates a bond at neutral in the basement J-box (inverter ouput), via the meter’s tone, but oddly, the tone is ‘strangely distorted’ though steady…Again, this is with the inverter OFF and disconnected from battery…

At this point, not too sure about the distorted continuity meter tone??…Will check the ProSine inverter manual next…

Many Thanks for your interest, making these written notes helps to keep my thoughts connected - lol :)

3 tons

The Generator terminals: If there is power to them then the switch assumes that is the input you wish to use.

Shore power does NOT override generator

Some systems however use a "Relay Race" method
Whichever has power. Keeps power.

This is a Uber compacted truck camper with a cascading elect system approaching a Diesel pusher, so this I’m sure will take awhile - pulling the inverter to access another buried sub-panel is no picnic - a several hour job in and of itself…Inverter output shows normal, so I’m digging deeper yet - mirrors are my best friend - lol

3 tons

OK then it is easy. Work back with your voltmeter and find the step point from 119 to 32.

time2roll wrote:

3 tons wrote:
What’s inexplicable is that I’m reading a consistent 119vac at the inverter output (at the ATS), yet it wont activate the relay -

Have you checked for 119v on the ATS coil?

Yes, as previously stated 119vac (open wires) coming from the inverter’s sub-panel, but once connected to the ATS, drops to 32vac at the gen-in terminals, thus relay inoperable…However, once I connect the jumper from the ATS’s gen-in hot terminal to the chassis, the relay contactor becomes perfectly operable…Up until this ATS install point, the camper’s worked perfectly - ATS is pointing out to me “Houston we have a Problem”, a problem that heretofore has somehow been of no apparent consequence…JMO,

3 tons

CA Traveler wrote:
Inverter bonding would only occur when there is no AC input and the inverter is converting DC to AC vs shore passthough. Try the 3 light household tester on the inverter output as they should show a problem with a floating neutral.

Will do, but upon further examination, I’m finding some neutrals in the main tied to the ground bar, while some other neutrals are not tied to the neutral bar…Looks like in someway the ATS relay coil was able to sense this defect, yet WOULD operate (via the inverter) IF I ran the jumper from the ATS’s gen neutral terminal to chassis ground…

So it looks like the ATS’s relay was just an indicator of past bad things gone wrong at the main panel…Funny that all these years and no sign of a problem (or GFI trips) until the ATS install…

Main panel is a congested birds nest (both up front and behind - ugg)…

It won’t be fun :(

3 tons