Semi Electrical Emergency- Need Help

I have posted above blowing a surge protector in the entertainment center area before.  It happened again today, just now and killed the AC power to the coach.  12 V power was still working.  I have a Progressive Dynamics Surge Protector hard wired in the power bay.  It showed no errors and a constant 117-118 volts on both 110v legs.  I have a kill-a-watt.  I was able to flip the breaker off at the source pedestal and flip it back on and get power back in the coach for a few minutes.  The kill-a-watt showed 135-140 volts at every outlet.  Then everything went out again.  No breakers are throwing.  I fired up the generator and have 116 volts at every outlet and things are fine running that way.  Something in my coach is spiking the voltage.  What could it be?  It seems to me it could be the inverter?  Is there some way to bypass it until I can get this sorted out.  We are full time and in South Florida so we need the AC practically 24 hours a day.  When this happens the Heart Interface Inverter Panel inside goes black.  But I still have 12V power.  When running from AC I can hear the Inverter kicking in and out.  And its pumping tons of amps for a few seconds then less... back and forth..  My batteries are good.  Sorry for the long post, but I am at my wits end trying to figure this out.   

That voltage is way too high... The PDI surge guard should be cutting you off to protect you from over voltage.  Why it is not showing an error code I do not know.

Could also possibly be a lifted (or loose) neutral wire (main) in the pedestal or in the coach circuit breaker panel or somewhere between.

Guys the PDI protector is showing 117-118 volts solid.  The voltage spike is happening after the power goes through the PDI surge and gets through the transfer switch to the outlets.  I have flipped the 30 amp breaker that the inverter is on off and this kills all power to my outlets.  If I flip it back on the Kill-a-watt shows 140 volts and will spike to as high as 170.  I immediately flip the inverter breaker back off.  I have no clue exactly how the inverter/converter works, but it is in between the power coming in to the coach which the PDI says is good and the outlets which are reading way too high voltage.  Could the inverter in any way cause this?  Its like it is trying to invert power even when turned off on top of the incoming AC.  On another note, with AC disconnected when I turn on the inverter, I am getting no voltage at the outlets and 30 HZ.  So something is definitely screwy here.  With the breaker to the inverter off, I am able to run the Fridge on AC and my Air Conditioning because they are not on the inverter circuit.  I have no way of knowing if they are getting this over voltage too.  If the problem is the inverter, then they are not.  I hate to run them, but I have to have AC.  So far they have been running this way for almost one hour with no problems.  Can my inverter be repaired, or better to replace?  How to diagnose?

Paul, to me it sounds like the Heart interface isn't regulating it's load. There are two switches to turn it off, besides the breaker feeding it. One in the panel above the stove and another one on the inverter in the compartment. The decision to repair or replace is for others to help you with, I repaired mine, a simple fix that would not work for your problem. My vote is to replace if funds are available, they aren't cheap.
Your PDI says pedestal voltage is correct, that's what's running the AC so I say let her run. That said, there are others here with A LOT more experience than I.
Water Dog has a good point,... a loose neutral is like a gremlin running around...strange thing happen.

The thing that isn't making sense is that the inverter's built-in transfer switch should be passing the shore power direct through. There is no transformer or other circuitry in the way when not inverting.  And based on your comments about generator power being ok, it does pass through power through as it should, which tells me the inverter is probably ok.

I'm wondering if you maybe have a loose neutral connection where shore power goes to the main transfer switch. The PD is reading ok power form the shre post, but its not ok once past that. The only thing in between that is not also common to the generator side is the wiring between the PD and the shore side of the transfer switch.

A corroded or partially broken neutral will cause the voltage to float high or low in a seemingly random manner. It's really not random, but it varies with factors you & I cannot readily see.

I agree that this sounds like a broke or loose neutral in the pedestal or in your cord.  If the Generator is keeping power stable than this problem goes to outside of the rig.

  If you have a secondary cord that you could borrow - switch to it and see if it solves the problem...  If not go try a different pedestal...  Good Luck

Made it through the night..  Back at it this morning.  So I know I have clean power coming into the PDI, but I also know I have clean power coming from the Breaker Panel in the coach to every outlet that is not able to be inverted.  For Instance the refer outlet gives clean voltage and runs no problem.  The Basement AC is getting clean voltage and running no problem.  I also wired a new circuit some time ago for my Hott Rodd and it is providing clean voltage.  I have run an extension cord from that outlet to provide some small power inside the coach because all other outlets can be inverted and show high voltage.  If the problem was outside, I shouldn't be getting clean power to other outlets in the coach.  Here is a twist....  There is a 30 main breaker on the panel that is the inverter.  Then there is a 30 amp sub panel with all the circuits wired to the inverter.  Does this tell us anything else?  Also I blew my first surge protector before installing the PDI.  What I still can't get to add up is the generator providing clean power everywhere.  I am going to pull the breaker panel out and check for any loose connections.  I just really don't know where to go after that.  I don't want to go and order a new inverter if that isn't the problem.  Thanks for all the suggestions.

Hey guys; nobody is picking up on the 30HZ!  Seems to me that is a big clue.  I'm not all that  knowledgeable in commercial A.C.  I'm wondering if the lifted neutral throwing both phases to one circuit would make the kill-a-watt see 30 HZ.  There is no way the pedestal A.C. frequency is at 30HZ.  It seems to me that if it is not the lifted neutral and the kill-a-watt is to be trusted the only thing that could change the frequency would be the inverter.

The only time I get 30HZ is when AC is turned off at the pedestal and I try to turn on the inverter.  And actually this is happening with the breaker off to the inverter.  I get a reading of 000 volts and 20-30 hz.  I would think with the breaker to the inverter off, nothing should be getting through to the outlets.  Maybe just something residual in the lines?  As of right now with everything back on I am getting normal power again.  I can't trust this though with what happened yesterday.  Interesting to note that the outlets that are wired to the inverter are showing 121-122 volts with the AC running.  The other outlet not going through the inverter is around 117.  The AC always draws the voltage down a little, but it doesn't affect the inverted outlets for some reason.  My problem now is how to trace this down when it has fixed itself again.  And when it runs 140-170 volts it throws no breakers so this could be very dangerous.

You had not mentioned that the 30HZ was only present when the voltage was "0".  That is some kind of fluke (no pun intended).  What about the high current readings, are those credible? 

Can't see where you could have 30hz and no voltage unless the voltage is too low (millivolts) for the Kilo-watt meter to register, other than an anomaly (fluke)... The only thing that can spike the alternating voltage is the voltage being produced by the inverter, if your incoming voltage from the pedestal and that of the generator is good at all times.

I have been under the impression that inverters were somewhat intelligent in that if 120V was present from the pedestal or generator, they were effectively shut down and a built-in transfer switch supplied the associated outlets with pedestal or generator voltage. You seem to indicate that only certain outlets are connected only to the inverter. Are they dedicated and are normally dead otherwise or do they correspond to my understanding???? Otherwise, the transfer switch in the converter does not seem to be doing its job either, maybe burned/stuck contacts. Sure looking like a defective inverter...

Worst case, shut down the output breakers on the sub panel since the only outlets affected seem to be those wired  to the inverter. Check all wiring behind that panel too.

You should be able to simply turn the inverter off altogether either by switch or DC circuit breakers on the input as it is NOT likely supplying your air conditioning. And yes, that is one reason why I am in Canada and not Florida at this time of year... Heh heh

It sounds as if your inverter is acting strangely. Have you tried putting a  load on one of the inverter outputs and then measuring where you are getting 000 and 30HZ. The reading may just be noise from something coupled into the line.

Or possibly the inverter is operating despite having an AC input. That might account for the high voltages. There must be a sensor (I'd think it's switched, but contacts do stick) to prevent the inverter from running when AC in is available. Other than a bad neutral, this is about the only thing I can think of that could account for the high voltages.

Or Murphy has taken up permanent residence!

Ernie

It definitely seems that the inverter is doing more than bypassing the incoming AC voltage.  But right now, it is working fine.  I have turned the inverter off via the remote panel swtich per the user manual, but I think the voltage was still measuring high(that was yesterday and I might not be remembering correct).  Had a service guy out and just left a few minutes ago.  He suspected the inverter too, but had no way of testing it.  He decided the safe thing to do now was to take the incoming AC lines to the inverter and wiring them straight to the outgoing AC lines out of the inverter.  He removed the inverter incoming AC and outgoing AC lines and capped them off.  This is allowing the charger to still work but if the inverter tries to kick in it will not send power anywhere because the lines are capped off.  I am getting 121.4 volt readings at all outlets right now, but I am still not convinced that was the problem because I was getting the same reading this morning with the inverter on.  I am going out to buy a couple of new surge protectors to replace the ones that fried.  I am going to have them replaced under warranty, but I want something to put back in place until then in case this happens again.  I guess I will just keep an eye on things for now and know that I don't have any inverting capabilities.(Rarely use it anyway).  I would go ahead and order a new inverter but I just have that feeling that its not the problem.  I appreciate the help, this was a bit of a scary situation.  I still don't know why the microwave, bedroom clock, surge protector in the bedroom didn't fry too when we were getting 170 volt spikes yesterday.  Will update when I know more.

He removed the inverter incoming AC...

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Huh? If he did that, you have no charging. It takes 120v input to produce the 13+v for charging.

I'm thinking he just capped off the 120vac output and ran a second line to bypass the inverter and feed the secondary 30A breaker panel direct form the main panel.

The thing that messes up all the above theories is that the inverter apparently works as designed when the power comes from the generator. But that power comes from the same main breaker panel, via the same 30A circuit, and goes through the same internal transfer switch in the inverter. If that is accurate data, then the problem has to be elsewhere. But if it's not, then it could be the inverter itself that is acting up.

Some (most) of your symptoms can be explained (at least in theory) with the "loose neutral" diagnosis.

In a 50amp service, if one leg spiked to 170vac, the other probably dropped to about 70vac.

The inverter could be expected to do weird things if it sensed 170vac on the input, as this would be way out of the acceptable input range and would trigger it into invert mode (producing it's own ac voltage, or worse).  This would NOT constitute an inverter failure.

My money is still on a loose connection between the PDI and the input to the main transfer switch.  The symptoms will probably return when least expected (or desired).

I would not blame the inverter without further testing.

The fact that the generator performs correctly, and in concert with the inverter, tells me that the problem is prior to the inverter.

Gary RV Roamer said:

Huh? If he did that, you have no charging. It takes 120v input to produce the 13+v for charging.

I'm thinking he just capped off the 120vac output and ran a second line to bypass the inverter and feed the secondary 30A breaker panel direct form the main panel.

The thing that messes up all the above theories is that the inverter apparently works as designed when the power comes from the generator. But that power comes from the same main breaker panel, via the same 30A circuit, and goes through the same internal transfer switch in the inverter. If that is accurate data, then the problem has to be elsewhere. But if it's not, then it could be the inverter itself that is acting up.

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He definitely capped the output, but ran no new wires.  Took him about five minutes to do it while I watched.  The charger is working but he said if for some reason the inverter kicked in it wouldn't have anywhere to send the power.  There were hard wires(three) with wire nut connectors on the AC Output side and the same three on the input side.  These were wire nut connected to three soft wires.  He pulled the soft wires out of each wire nut and capped them and connected the hard wires together.  These wires were behind a panel he removed at the front of the inverter, but there were also wires going into the inverter at the rear.  I am not sure how its still getting power to the charger.  But the inside panel shows charging and fluctuates if I put a 12v draw on(i.e. turning on several lights). 

Just Lou said:

Some (most) of your symptoms can be explained (at least in theory) with the "loose neutral" diagnosis.

In a 50amp service, if one leg spiked to 170vac, the other probably dropped to about 70vac.

The inverter could be expected to do weird things if it sensed 170vac on the input, as this would be way out of the acceptable input range and would trigger it into invert mode (producing it's own ac voltage, or worse).  This would NOT constitute an inverter failure.

My money is still on a loose connection between the PDI and the input to the main transfer switch.  The symptoms will probably return when least expected (or desired).

I would not blame the inverter without further testing.

The fact that the generator performs correctly, and in concert with the inverter, tells me that the problem is prior to the inverter.

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I am definitely not sure it is the inverter.  But why would a loose ground cause this problem for a few minutes and then not again for weeks and months.  The coach is sitting still so nothing could be rattling around, etc.  Also this problem happened the first time before the PDI was put in...  I am going to check grounds on the output side of the PDI and the AC input side of the ATS.  The thing with the generator working everything fine could possibly be only because this intermittent problem wasn't showing up during those few minutes I ran it and tested everything.  This morning before service came, I was running everything normal and getting clean voltage with inverter on, etc.  So the problem disappeared which makes it so hard to diagnose.  I have replaced the surge protectors and have everything up and running, but no way to know for sure when the problem is solved due to its intermittent nature.  I only know when the surge gets fried and even then no breakers have ever thrown.  It would be scary if this happened when we weren't here.  I am watching my kill-a-watt every while things are running now, but I can't keep my eyes on it 24/7.

bigpemby said:

I am definitely not sure it is the inverter.  But why would a loose ground cause this problem for a few minutes and then not again for weeks and months.  The coach is sitting still so nothing could be rattling around, etc. 

  I only know when the surge gets fried and even then no breakers have ever thrown. 

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It could be a loose connection in the neutral at the pedestal outlet itself. On a 50 amp service, if your neutral has no way to get back to the source, one leg will provide power through one hot leg to whatever is plugged in and return through the neutral bar in the panel, up an adjacent neutral wire, through whatever is plugged in to a circuit on the other leg and back to the  a circuit breaker on the second leg. In essence sending 240 volts to two separate (or more) loads wired in series, and as Gary said resulting in an unbalanced load due to the different resistance in the loads that are plugged in. You wouldn't experience it with the generator because the neutral returns to the generator in that case. This over/under voltage won't trip circuit breakers since they are tripped by high current, not voltage.

If in fact this is what happened, there could have been a low enough voltage seen at the inverter transfer switch from the unbalance, to cause the transfer switch to release, thus causing the inverter to kick in at the same time.

Maybe something (wind?) moved the plug a little at the pedestal? .... Of course, it's all just a theory, but it might be worth wiggling stuff around.

bigpemby, be careful with your terminology when discussing the possibilities and probabilities here.  Gary, Dennis and I have stated the possibility of a loose NEUTRAL somewhere in the shore voltage input path.  Our discussions and explanations apply to the neutral wire in a two hot wire 50amp RV service configuration. 

Your reference to "open grounds" could be confusing, when discussing this situation with your tech, as that is an entirely different matter.

Conventional hot and neutral, or hot and ground, two wire circuit logic doesn't simplistically apply here.
The fact that circuit breakers were NOT tripping, lends support to our theories, as well.

But hey!  I've been wrong many times.

Are you in a RV park where you can plug into a different pedestal?