Shore power and generator

Bill.Satellite wrote:
When you start the generator the transfer switch will disconnect the incoming shore power connection and your coach will be powered by the generator only. The generator is always the primary power source so you cannot run the generator and still have incoming power unless you kill the breaker at the generator to prevent power from coming into the coach. This is a good thing as not only do you want to know if the generator works, but you want to run it under load from time to time to keep it in good operating condition. When you shut down the generator the shore power will be restored automatically via the transfer switch.

yes we all know that as its been presented as such about 22 times so far and I agree. what the argument is that some posters feel its wrong and risky and one should disconnect the SP before starting gen set and not/never rely on the TS to do its job for one reason or another

kemer wrote:
THANKS....dumb question....transfer switch, I assume it's on the generator itself? I'm also assuming that by switching it, it'll prevent power going from generator to RV? Thus just letting the gen run?

It's not a Dumb Question", it hopefully was an un-necessary one. If you don't have a owners manual for your rig and one for all your appliances and features, Google them and download them and then read them. I sometimes mind answering the same question over and over, but I learn so much each and every time I read or re-read the manuals for my Winnie, I can't be surprised about how much folks miss when they do read their manuals. Please don't be upset when someone says, "Read The Manual", they mean well.

only time the breaker will blow on inverter in that situation is when you overload the system or short out something(gfi)
really nothing what so ever to do with what the op asked in the first place

usersmanual wrote:

rgatijnet1 wrote:
Not sure about all inverters but when I fire up the generator, or am hooked up to shore power, the inverter still receives 120 volt power to power the charger portion and it is the inverter/charger that is charging the batteries. Depending on how the charger portion is programmed, it can draw quite a bit of current when charging the batteries. I also have pass-through current with my inverter when hooked to shore power or generator which can trip the inverter breakers stopping the 120 volt output to my outlets.
It may not be inverting but the inverter/charger still can draw a sizeable amount of power.

correct;; but should not trip breakers;; theres a fault there somewhere;; the generator should be able to start when voltage gets to a certain level( settable by owner) to recharge batterys but should not trip breakers
the only thing comes to mind is the circuit your charger is on has a another draw and combined they could exceed 15 amp draw at start up

The charger does not trip the inverter breaker. The charger has it's own breaker that protects the charger portion. It is the inverter breakers that can trip when you are on generator OR shore power. This is from the pass-through current that passes through the inverter when it is not inverting. This is a very common problem and is one the first things people on this forum are told to check if they lose 120 volt power in their coach. These are the breakers on the inverter itself and will usually trip before any of the breakers in your main electrical panel.

Perhaps as JimInMich alluded to, the OP doesn't even have a transfer switch. My transfer switch is me unplugging the shore power cord from the pedestal and plugging it into the generator junction box socket. In the event that he doesn't have a transfer switch then no harm will be caused by running the generator while the shore power cord is plugged into pedestal power. His reason for doing it is irrelevant to the answer.
Happy Trails,
Al

rgatijnet1 wrote:
Not sure about all inverters but when I fire up the generator, or am hooked up to shore power, the inverter still receives 120 volt power to power the charger portion and it is the inverter/charger that is charging the batteries. Depending on how the charger portion is programmed, it can draw quite a bit of current when charging the batteries. I also have pass-through current with my inverter when hooked to shore power or generator which can trip the inverter breakers stopping the 120 volt output to my outlets.
It may not be inverting but the inverter/charger still can draw a sizeable amount of power.

correct;; but should not trip breakers;; theres a fault there somewhere;; the generator should be able to start when voltage gets to a certain level( settable by owner) to recharge batterys but should not trip breakers
the only thing comes to mind is the circuit your charger is on has a another draw and combined they could exceed 15 amp draw at start up

Not sure about all inverters but when I fire up the generator, or am hooked up to shore power, the inverter still receives 120 volt power to power the charger portion and it is the inverter/charger that is charging the batteries. Depending on how the charger portion is programmed, it can draw quite a bit of current when charging the batteries. I also have pass-through current with my inverter when hooked to shore power or generator which can trip the inverter breakers stopping the 120 volt output to my outlets.
It may not be inverting but the inverter/charger still can draw a sizeable amount of power.

MrWizard wrote:
lets say you are running the inverter for the fridge ? or whatever
and you pull up and plug in to shore power
at the moment 120v is applied to the inverter-charger combo, it stops inverting and pulls in the 120v TS aka input relay, it might be micro seconds delay that you can't see but it shut off the inverter 120v out while doing the switch

in the reverse case, you are on shore power, and it fails
no incoming 120v, charging stops, invert comes on and TS relay drops out, to default to inverter power
in fact both TS switches change state, the house TS switch drops out the instant shore line power fails, before the invert TS changes state

the problem with the house TS and gnerator shore connection
is that it often fails by sticking one set of contacts
a 30 amp switch , switches (4) wires hot and neutral on each side gen/sp to the house input
a 50amp switch , switches (6) wires 2 hots and neutral on each side gen/sp to house input

when one contact sticks you end up with one wire from the gen and one wire from the sp connected to the RV
the gen becomes the path for the return side back to shore box
the gen is not in phase and cannot control the utilty input
it is forcefully tried to sync with utility power
the EMF forces involved are not trivial
this is a dangerous thing

usermanual
you type faster than I do

Actually with the Surgard 41260 should prevent that from happening because it verifies the source is appropriate before letting it through. Also noticed that it has the capability of starting the generator automatically, not only if the pedestal loses power, but also if it faults (lose neutral, lose a leg, lose ground, etc).

In as much as I understand what you are saying - I'm OK with the risk. I think the more sophisticated systems are protected as well as can be expected, which may not be the same as the older ones or a 5er system with onboard generator.

i will agree that it is NOT often

but the risk of spending thousands $$ to repair or replace a built in genset
over something that is so easy to avoid is just not worth the risk

like i said in another post, utily failure don't happen to you every month much less every week or everytime you go camp, so cumulative damage to contact being used the for what is designed in almost nil

but routine power switching on HOT shore power is what creates the damage to the contacts and the danger of having the TS switch develop a sticky contact


analogy
the brakes on your motor vehicle will stop you in an emg
drive everyday slaming on the brakes for quick hard emg stops, and one day they will fail

like manual says it will auto start and switch IN CASE of a power failure
the manual does NOT say you can do a power transfer from hot shore to generator anytime you feel like
and like the manual says it gives priority to generator
meaning once you are on generator power
it will not switch back to shore power UNTIL you turn off the Generator
again only ONE hot power, generator off then the TS can engage shore power

just because you can push a button and start the generator while plugged in
does not mean you are supposed to,
it will not do it automatically while shore power is hot

the problem with the house TS and gnerator shore connection
is that it often fails by sticking one set of contacts

certainly possible and most likely has happened but I question the often?