Basic Question About AC Power Wiring

[HadEnough]

How are RVs usually wired up?

I have a standard arctic fox RV and I’m having trouble with the AC portion of the wiring.

Symptoms:

*After running an air conditioner for 4-5 hours, off an external generator connected to the shore power cable, I get a brownout” situation and the microwave turns on and off every second or two repeatedly during this brownout.

*Its getting worse. Sometimes I get the same thing on startup. Other times it randomly works great for hours and hours.

*when I use the onboard generator, it will either work great or it will have the same type of problem as the external. HOWEVER, when the external generator would have the brownout or cycling, the onboard generator is smarter and just shuts down.

*there seemed to be a VERY long delay tonight using the onboard generator before the power came on.


So far I’ve looked at the transfer switch. I opened it. Hard to see the contacts, but they didn’t really seem to do anything actually probably because I was on the shore power generator. And it was working fine.

So my question is related to diagnosis.

What components are involved?

What components are common to the shore power and the onboard generator such that they can cause brownouts, cycling on/off of power and the onboard generator to decide to shut down?

I’m looking hard at the automatic transfer switch but I don’t see any problem.

It seemed to get better a bit when I exercised the main breaker on the panel, but it’s intermittent and that may not even be it.

What components are there to check?

[3_tons]

Got it, thanks for clarifying...

3 tons

[HadEnough]

3 tons wrote:

HadEnough wrote:
Problem came back.

Watched the external generator brown out to 90V. During a warm day yesterday after a couple hours running the air conditioning.

Was able to finally do a comprehensive test of everything since it stayed at 90 for a long time.

Confirmed the on board generator is functioning ok. Not perfect. Needs to be sped up. It’s putting out 110/109 at 56hz. But the power is stable and working properly.

The wiring is not currently an issue from the external generator to the air conditioner.

The wiring inside the external generator isn’t an issue.

That leaves one and only one thing to be the problem.

The AVR inside the generator is misbehaving. That’s why it’s so intermittent. It’s an electronics problem.

Replacing the AVR as soon as I can get one.

Not sure what a AVR is but I’m glad you’re on top of it...However as I recall this malady occured when using either generator - is this not the case??

3 tons

The AVR is the electronic circuit board that replaces the capacitor in modern generators. Like most things electronic, it’s a piece of junk. Ha ha

But yes. I had initially thought the two generators behaved the same because by crazy coincidence, the onboard onan genset decided to cut out at the same time the other one was misbehaving.

I like to post a conclusion to any threads a start so that if other people run into the same problem, they find an answer.

[3_tons]

HadEnough wrote:
Problem came back.

Watched the external generator brown out to 90V. During a warm day yesterday after a couple hours running the air conditioning.

Was able to finally do a comprehensive test of everything since it stayed at 90 for a long time.

Confirmed the on board generator is functioning ok. Not perfect. Needs to be sped up. It’s putting out 110/109 at 56hz. But the power is stable and working properly.

The wiring is not currently an issue from the external generator to the air conditioner.

The wiring inside the external generator isn’t an issue.

That leaves one and only one thing to be the problem.

The AVR inside the generator is misbehaving. That’s why it’s so intermittent. It’s an electronics problem.

Replacing the AVR as soon as I can get one.

Not sure what a AVR is but I’m glad you’re on top of it...However as I recall this malady occured when using either generator - is this not the case??

3 tons

[HadEnough]

Problem came back.

Watched the external generator brown out to 90V. During a warm day yesterday after a couple hours running the air conditioning.

Was able to finally do a comprehensive test of everything since it stayed at 90 for a long time.

Confirmed the on board generator is functioning ok. Not perfect. Needs to be sped up. It’s putting out 110/109 at 56hz. But the power is stable and working properly.

The wiring is not currently an issue from the external generator to the air conditioner.

The wiring inside the external generator isn’t an issue.

That leaves one and only one thing to be the problem.

The AVR inside the generator is misbehaving. That’s why it’s so intermittent. It’s an electronics problem.

Replacing the AVR as soon as I can get one.

[HadEnough]

The problem seems to be gone. Had a good afternoon of generator running to run the air conditioner.

External generator was at 120 under load at 58.5Hz. I left it there. That seems to be making the transfer switch happy.

I think the onboard generator deciding to shut down a couple times may have been some kind of fluke.

So it’s working, but I don’t have a full understanding of what happened. Possibly all the wires I tightened played a role as well.

[KMLsquared]

HadEnough wrote:
Status report:

Since the problem is transitory, it’s going to take a long time to test. I got that plug in voltmeter from up thread. I also got a new multimeter for testing.

I tightened every single connection everywhere throughout the power system.

Immediately on startup of the generator for fine tuning, I saw 70 volts on the plug in meter as it cycled on and off about once a second.

No appliances at all were on except he battery charger, which is tiny and a default.

While it was cycling and not harming anything I checked some connections. Once the issue went away, I finally did what I had set out to do which was to adjust the generator speed to get perfect power. It was at 108 which is a little low. The frequency also was low. I moved it around but and ended up at 120v and 58.5Hz, under the load of the electric hot water heater. Good power. I couldn’t get exactly 60Hz without going above 120v so I stayed at those figures.

I haven’t seen the issue again yet, but have only used the microwave very briefly. It hasn’t been air conditioning weather in Florida lately. Ha ha.

I’ll update with new info in case anyone else has a problem like this.

FYI: I have a similar plug in meter and it always reads 105 when the gen is heavily loaded. I checked with a good meter and found that the voltage was really 110. Its a good idea to verify the meter is accurate.

[enblethen]

Adjust it to get right at 60 hertz. Your voltage without load can go nearly 125 volts. Once genset comes under load, the voltage will drop.

[pianotuna]

Hi,

I would move it up to get 60 hertz so long as voltage doesn't go more than about
124 volts.

[HadEnough]

Status report:

Since the problem is transitory, it’s going to take a long time to test. I got that plug in voltmeter from up thread. I also got a new multimeter for testing.

I tightened every single connection everywhere throughout the power system.

Immediately on startup of the generator for fine tuning, I saw 70 volts on the plug in meter as it cycled on and off about once a second.

No appliances at all were on except he battery charger, which is tiny and a default.

While it was cycling and not harming anything I checked some connections. Once the issue went away, I finally did what I had set out to do which was to adjust the generator speed to get perfect power. It was at 108 which is a little low. The frequency also was low. I moved it around but and ended up at 120v and 58.5Hz, under the load of the electric hot water heater. Good power. I couldn’t get exactly 60Hz without going above 120v so I stayed at those figures.

I haven’t seen the issue again yet, but have only used the microwave very briefly. It hasn’t been air conditioning weather in Florida lately. Ha ha.

I’ll update with new info in case anyone else has a problem like this.

[HadEnough]

dougrainer wrote:

time2roll wrote:
I find it odd to be the transfer switch since both the utility cord and on-board generator have the same issue.

Maybe start with isolating some circuits like setting the fridge and water heater to propane only.

You are not understanding a Transfer switch and also HOW the OP is doing his 120 power.
1. He states that his ONBOARD Gen is having the problem
2. He states his stand alone genset has the same problem
3. YES, his Stand alone uses the Shore power cord
4. BUT!!!!! His Stand Alone STILL uses the ATS relay with its contac points. The INPUT points are on BOTH sides of the relay. So, over the years he has probably pitted the points on Shore side and also on On Board Genset side. That is why I suggested he BYPASS the ATS and wire direct. That will determine very quickly what his problem is. Doug

Exactly.

[dougrainer]

time2roll wrote:
I find it odd to be the transfer switch since both the utility cord and on-board generator have the same issue.

Maybe start with isolating some circuits like setting the fridge and water heater to propane only.

You are not understanding a Transfer switch and also HOW the OP is doing his 120 power.
1. He states that his ONBOARD Gen is having the problem
2. He states his stand alone genset has the same problem
3. YES, his Stand alone uses the Shore power cord
4. BUT!!!!! His Stand Alone STILL uses the ATS relay with its contac points. The INPUT points are on BOTH sides of the relay. So, over the years he has probably pitted the points on Shore side and also on On Board Genset side. That is why I suggested he BYPASS the ATS and wire direct. That will determine very quickly what his problem is. Doug

[3_tons]

Oops, Disregard

[HadEnough]

enblethen wrote:
Most transfer switches only uses logic on the auxiliary power supply. The OP uses shore power to feed rig from portable gensets. Transfer switch logic would also not cause brown out type issue. only thing in transfer switch that could cause problem is contacts.

This little tidbit is just the kind of stuff I was hoping to learn on this thread. Thank you.

That was actually my first guess. The contacts.

[HadEnough]

time2roll wrote:
I find it odd to be the transfer switch since both the utility cord and on-board generator have the same issue.

Maybe start with isolating some circuits like setting the fridge and water heater to propane only.

Way ahead of you. Being off grid/boondocking, it’s always all set to propane.

Generators only come on when we need to microwave or use air conditioning. The rest is propane and solar.