Electrical Problem- Blew Surge Protector

I will try to make this short.  Very weird problem so let me try to explain.  Happened about six months ago and just happened again tonight.  I have a surge protector in the AV cabinet at the front of the coach.  It is plugged into AC outlet in the cabinet.  Have TV, Sat Receiver, DVD Player, etc. plugged into the surge protector.  I was watching TV tonight and all of a sudden the TV turns off and I smell that funny burned plastic smell.  Since this happened six months or so ago, I knew exactly what it was.  Surge Protector blown again.  There was no power surge or at least loss of AC power that I can tell.  Everything else in the coach continued to operate.  I did notice a louder humming from the Inverter/Converter and the interior lights dimmed and then got bright.  I have a spare surge protector and hooked it up and everything is running fine.  My inverter is turned off so it should not have tried to come on even if we had an AC power loss.  The outlet where the surge protector continues to blow is an outlet that is powered by the inverter and it has me thinking for some reason the inverter is sending power there while we still have AC power causing an overload.  Why this would happen, I don't know, but it just seems tied to the inverter somehow.  Also when this happened I went to check the inverter digital panel in the kitchen and noticed it showed it was momentarily pumping 50 plus amps to the batteries for some reason.  It quickly went down to 10 amps which is where it normally is if we have a few lights on.  Sometimes it goes down to 5 amps with hardly any 12V draw.  I hope I am giving enough information and this is making sense.  Does anyone have a clue as to what could be happening here?  No blown breakers, fuses, etc.  Just simply replace the surge protector and everything is fine.  I guess it could be a coincidence, but I don't think so.  I am concerned this is evidence of something bigger lurking.  Thanks for any help.

Big, sorry to hear about your problems and I am no electrician but a couple things come to mind. Do you have a main surge protector for main incoming power? I just finished inst one for in laws along with a new pc board for the heat pump! This protects MH on shore power as well as gen set.
I understand you are thinking inverter but is it possible the protector you are using (and burning up) is too small for the loads going thru it?
I'm thinking it would be difficult for the inverter to power on and apply AC voltage, then go back off and work normal again.
If your shore power was to surge more than say 10v or so I would think your battery charger and batteries would see the relationship in DC volts. This could be the cause for the lights getting bright, then dim, as the shore voltage changes and the charger adjusts output to the batteries and the 12v loads in the MH.
One other thing, have you checked your house battery condition? When you talk about the charger side of the inverter putting various amp loads to the batteries I would consider this normal as mine adjusts throughout the day also. I would not think it should apply that much current unless it was trying to equalize the batteries or it sensed a very low battery condition. You might have a cell starting to short out? Wouldn't take long to isolate each battery and load test them. Good luck.

I am also just guessing here. Is your inverter a modified sine wave inverter or a pure sine wave inverter? If is a modified sine wave that could be causing the surge protector problems. Ned will probably have the real answer and he should be along shortly. 

I would guess you had a momentary surge on the shore power, and then it went to very low momentarily.  That would have transferred the inverter from shore power to powering the outlets, although you say it was off.  We never turn ours off, even though it won't be actually supplying power as long as there is shore power present.  Most things won't notice the change so they kept running.  The dimming of the lights would indicate the inverter coming on and pulling more power from the batteries.  When the shore power came back up, the inverter would switch off and the charger would switch on, the 50A charging current, tapering off quickly to the float level would indicate that as well.

The surge protector did its job when the initial surge occurred.

I do have a Progressive Industries hardwired surge protector outside.  It wasn't damaged and did not indicate any error codes.  The inverter was definitely off but somehow it does seem to have been involved.  I noticed also the coffee pot clock blinking so we did lose power all over the coach.  I have another surge protector in the bedroom running TV, Sat receiver, etc.  Computer being charged on another outlet, etc.  All of these outlets powered by the inverter too.  But nothing happened to them.  And this is the second time this has happened in six months at the exact same outlet.  I guess coincidence?  Why didn't other surge protector's blow?  Very very interesting.

The recommendation is to not have more than one surge protector in a circuit.  Since you have the PI unit on the shore power protecting all the house circuits, you shouldn't have the other ones on the individual circuits.

Can't see how multiple surge protection devices could hurt, though. It's a passive device.  Maybe one of our resident electrical engineers could offer an opinion?

I have multiples at our stick out - one outside and separate ones at the computer and big tv.

Here's one analysis of why multiple surge protectors can be a problem.  Scroll down to the reply from ScottMac for it.

Very interesting analysis.  I can say that the first time this happened I did not have the PI surge protector installed.  So this has happened one time before PI and one time after.  The first time this happened I actually saw some smoke from the surge protector(small amount).  I guess that could be normal.  This time just the smell.  Until I figure this out I guess I will keep a stock of surge protectors to change out each time this happens.  I don't want to know what would have happened to the TV or Sat receiver if they weren't running through that surge protector.  or... Maybe they would have been fine.

I don't see anything in that reference that would pertain to simple surge protection devices using MOVs. We aren't talking about UPS or switching power supplies - just something to clamp the voltage level and shunt excess to ground. As I recall the IBM example (I worked in their labs for 28 years) had to do with the massive motor-generators used in large scale computing installations and there were indeed strange problems when a multi-floor, multi-company office building had those beasts running on every floor and the external power dropped or surged. But that's a horse of an entirely different color (in my opinion, anyway).

Gary RV Roamer said:

I don't see anything in that reference that would pertain to simple surge protection devices using MOVs. We aren't talking about UPS or switching power supplies - just something to clamp the voltage level and shunt excess to ground.

Click to expand...

I agree with Gary. There should be minimal effect having serial protective devices especially since most input power monitors protect for sags/surges/spikes in input power. If there is a defective component after the input device (think one of your switching power supplies shorting and causing a surge inside the boundary), the input line power monitor is not designed to protect from these. Actual point of service surge protectors are fairly good at suppressing spikes and passive MOVs should not greatly change the power waveform.
Based on experience in aircraft electrical and electronic systems, protection was provided by various devices and layers consisting of MOVs, TRANSORBS, SCRs, etc. to protect for everything from defective power to nuclear EMP strikes. These layers were in series and worked quite well.
As Seilerbird asked is the inverter a true sinewave generator or modified (synthesized) sinewave? Modifieds actually have a squarewave component by the nature of their production using some filtering and actual loads to smooth them out. Solid state components designed to work with a pure sinewave may not work as well with modified sinewaves.
Of course that only matters if it isn't a pure sinewave inverter.
The other symptoms at the time are more interesting. They probably were not caused by an external change since your Progressive Industirestm surge protector gave no indication which places the cause inside the coach.
There was indication of a heavy load at the time of failure as evidenced by dimming lights and sound from the inverter. I would suspect that this load was caused either by the failure of the surge protector that died or the devices plugged into it. You might get a heavier duty surge protector for this circuit...If it occurs again, maybe the actual culprit will fail. :