Buzzing inverter on 2006 Georgie Boy

[95pace]

This weekend when we went camping and plugged into the campground power our switchgear box buzzed very loudly after turning the breaker off and on a couple times it stopped.Later on during the day it started again and I could not get it to stop,I did not have my meter with me nor did any of my friends who were also camping there so we could not check voltage.Ac worked fine as well as microwave and TV,just had never had this buzzing before it is also located at very back of camper under bedroom so it was kind of annoying.Anyone have any ideas why thing would buzz like that?Also according to previous owner this had beemn changed out before by camping world.

 

[Gary RV_Wizard]

The "switchgear box" is ???  Are we talking about the auto transfer switch, or maybe the converter charger or inverter/charger?  Orperhaps not sure which one was actually buzzing? Was it 30A service or 50A? 

The buzzing occurs when the combination of voltage and frequency resonates with the physical components. It's fairly common with transformers, but I would not expect much in the way of transformers in a 2006 - most everything is likely to be solid state electronics. Perhaps one of our resident electronics gurus can elaborate.

I would suspect that the source power had just the right combination of voltage and line frequency to set things off. The sensitivity to that can change as the components warm up, so the sound can come or go.  My auto transfer switch, which includes power monitoring and surge protection, sometimes hums rather loudly too. It seems to vary with the hook-up and temperature & humidity.

 

[95pace]

Yes the box is the transfer switch and I was plugged into 30amp with a dogbone cable.I have camped twice before with this unit in another campground with no buzzing there.I think you are correct about the voltage and frequency issue.I have camped at this campground many times before with no issues on my 95 Pace Arrow, just not on this site.We are going back in a couple weeks and staying on another site but will be taking my meter this time to check things out.

 

[Gary RV_Wizard]

Higher or lower than usual voltage can be a trigger, but it usually has to be coupled with a particular demand level (amp load) to produce the resonance. So the sound can come and go as you turn things on/off, or as power levels in the park fluctuate.