contactor switch

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RRAM

RRAM

Active member
Joined
Apr 28, 2014
Posts
36
Location
Medicine Hat Alberta
I have wired my inverter into my unit so that I plug the 30 amp into my inverter and then all my plugs are live.  Of course now I need to remember to turn off the breaker to the converter so it will not run.  Not a big deal but I  seen things about a contactor switch so I bought one.  The one I bought is a electronic controlled one so has the electric magnet.  I find it makes to much noise when it is on.  Not sure if a mechanical contactor would work as I think they need power to activate and power to switch.  Anyone deal with this issue?  I chose to do it this way as it was easy and less expensive then buying a switch. This makes is so I can never have an option for both inverter and shore power to ever be on at the same time.  The contactor held in mid air is pretty quite but as soon as it is mounted it sends out a hum. I tried to insulate the mount but still likes to reverb through everything.
 
Ummm why do you want the converter turned off?  That makes no sense at all.  When connected to shore power the converter is there to A, supply 12VDC to charge the battery, and B, supply 12VDC for lights, refer, etc.  With it turned off your battery does not get recharged.  Heck even when parked at home parasitic draw will deplete the battery sooner or later.  In 35 years of RVing my RVs were always plugged in at home.  Simply check battery water level monthly and your good to go.
 
donn said:
Ummm why do you want the converter turned off?  That makes no sense at all.  When connected to shore power the converter is there to A, supply 12VDC to charge the battery, and B, supply 12VDC for lights, refer, etc.  With it turned off your battery does not get recharged.  Heck even when parked at home parasitic draw will deplete the battery sooner or later.  In 35 years of RVing my RVs were always plugged in at home.  Simply check battery water level monthly and your good to go.
Click to expand...

not sure if I was not clear but when the inverter is turned on I want the converter turned off.  Not really complicated at all.  Just need to find a contactor that does not make noise when the inverter is on.
 
Hi RRAM

If I understand your post correctly you've wired an inverter straight onto your batteries and instead of plugging the RV into shore power your plugging it into the output of the inverter correct?

Where is the contactor wired into? Is it switching AC to the Magnetek converter/charger?

Electronic contactors don't have magnets, they're electronic. Mechanical contactors have magnets. Can you post the model or part number of what you installed?

If you're plugging the RV 30A power cord into either the shore power outlet or the inverter how could they ever both be on at the same time?

Go Power, Furrion, TRC and others all make transfer switches that will switch from shore power to inverter but they need to be wired in properly.

It sounds like you're trying to do this cheaply and the hum is the price you pay for the $$ savings. A proper transfer switch will cost some money but be silent. You need to decide if your wallet is more important than your ears.
 
to be more clear I have set up my inverter so I can plug my trailer cord into it just like if it was shore power. so technically I could run ac but that would not actually work with what i have.  Was best way to energize all the existing plugs and it will run the microwave I wanted to.  But of course doing that the converter would also come on so the switch was to stop that circuit.  It was just to make so I could not for get to trip the breaker to the converter.  I think now the main reason this contactor is louder then when on actual shore power is my inverter is modified not pure sine.  This seemed to be the less expensive way to go without buying an actual transfer switch in which case I would need one for 50amp as that is how my trailer came.  I just made a smaller better cord with a 30 amp end on it to eliminate a bunch of adapters.  I have never been to site that had an actual 50 amp place to plug in and we mostly boondock now anyway.
 
donn said:
Ummm why do you want the converter turned off?
Click to expand...

He wants the converter turned off when he's running on the INVERTER, not shore power.
As well it should be

Some of those "Contactor" switches (Also known as solenoids and relays) can indeed be noisy. I know how to quiet them down (Convert AC to DC filter it a bit. you may need to cut it down some and they go CLICK.. once) but how to tell you to do that safely .. .Well Let say I know how to do it safely but there is danger in playing with that stuff.
 
The contactor needs to respond to the 110 volt inverter output only. I don't know of a contactor that would differentiate between inverter or pedestal / generator. A transfer switch would seem to fix the problem but that would also be a problem when the 30 amp plug is plugged into the inverter. I am guessing a sustained chatter would occur with a transfer switch.

My guess is that you cannot have a fully functioning power selection unless the converter circuit is not wired to the inverter without a contactor. You could put a switch on the contactor but then it comes back to square one.

I think the problem is that you are using the coach power cord, and I assume an adapter, to send the power from the inverter to the coach power panel. If you were not doing that then there becomes a couple of options using a transfer switch and wiring the inverter to selected circuits and not the entire power panel.



Maybe posting a wiring diagram would help to better understand?
 
Wait.... The switch on the inverter will make it work as long as the contactor is wired to the inverter. Normally closed contactor that opens when the inverter is turned on. Idk it is getting late and I am tired.
 
Could you please explain where this contactor is wired into the system and what it switches?  I get what you are trying to achieve but not how it gets it done.  Where does the shore power cord plug into this scheme and what activates the contactor?  A simple sketch of the wiring would help a lot.


You state the contactor is noisy and attribute that to MSW power.  Is this only when MSW power is flowing through it? Is it ok when standard external shore power passes through?

 
What I did works perfectly other than the contactor I have has electro magnet that has a hum to it when I turn on the 110 power to activate it and is much worse hum when I use the 110 output from my inverter to trigger it.  Which is my whole issue.  Basically the contactor has a normally closed circuit so I cut the black wire on the panel breaker for the converter and run it through the contactor normally closed port.  Then I ran inverter power to the 110v port so that when I turn on inverter the switch snaps and opens the port with the converter wire which breaks that circuit.  Really kind of fun to have it work Just need to find a different contactor or maybe one day a different inverter.  Although it did hum on house power as well.  I have not found it yet but have heard there is mechanical ones that switch but I sounds like they won't trigger back unless 110 hits the other side so would take some more learning to make it happen and I think might be getting into just getting a transfer switch which by what I have seen of them is just this with a fancy box around it.
 
It hums because the laminations on the core are dry.  But if you convert teh A/C feeding it to DC add a bit of filtering and likely reduce the voltage a bit..  (back to 120 volts AC converted to DC can be as high as 1.414 times the RMS voltage  so you need to feed it around 80 volts AC rectrfied)
NOTE The voltages you are playing with here can be dangerous.  Then you add a diode to handle the inductive KICK when the power is cut off (else it can fry stuff upline like the AC-DC  Converter)

Easy for someone trained in that kind of work.. Not so easy if you are not trained.
 
And what turns the inverter off when you plug into a pedestal or run the generator? A manual switch?
 
Henry J Fate said:
And what turns the inverter off when you plug into a pedestal or run the generator? A manual switch?
Click to expand...

It does not need to be turned off.  I mean it does but it is not an issue as the cord for my  trailer can only be plugged in one place at a time.  Basically think take an extension cord to your rv plug  from your inverter.  I was not interested in trying to fight the cables that are all in my fuse box this was an easy solution to getting my rv plugs hot on inverter power.  I had a wired a single separate plug from the inverter but then once I had that going it seemed we always wanted to charge a phone or something in the kitchen and that didn't work.
 
John From Detroit said:
It hums because the laminations on the core are dry.  But if you convert teh A/C feeding it to DC add a bit of filtering and likely reduce the voltage a bit..  (back to 120 volts AC converted to DC can be as high as 1.414 times the RMS voltage  so you need to feed it around 80 volts AC rectrfied)
NOTE The voltages you are playing with here can be dangerous.  Then you add a diode to handle the inductive KICK when the power is cut off (else it can fry stuff upline like the AC-DC  Converter)

Easy for someone trained in that kind of work.. Not so easy if you are not trained.
Click to expand...

Well that bunch of words went right by me, just like the stuff the guys are the electrical place were rattling off.  I smiled nodded and said ok will see what I can do and left.  Now I will just flip the breaker until I talk to an electrician or someone who can just make it happen.
 
Sounds like you just need to try a different relay (contactor) and hope that one doesn't hum as much.  There are several 30A 120v SPDT relays on Amazon that run only $10-$20 each. A heck of a lot cheaper than a 30A auto-transfer switch.  But if you need DPDT, it gets more expensive.

https://www.amazon.com/Zettler-Miniature-Power-120VAC-AZ2280-1C-120A/dp/B0030G8SC8
 
RRAM said:
It does not need to be turned off.  I mean it does but it is not an issue as the cord for my  trailer can only be plugged in one place at a time.  Basically think take an extension cord to your rv plug  from your inverter.  I was not interested in trying to fight the cables that are all in my fuse box this was an easy solution to getting my rv plugs hot on inverter power.  I had a wired a single separate plug from the inverter but then once I had that going it seemed we always wanted to charge a phone or something in the kitchen and that didn't work.
Click to expand...

Certainly will provide power to all outlets.and I understand tbat but I still wonder what happens when you plug into a pedestal. If the contactor is energized, you will not have the converter charger on so I assume you have the contactor wired to the inverter  output (probably one of the other outlets) That will allow you to unplug from the inverter, plug into a pedestal and you will need to turn off the inverter to allow the converter to do its job. If the inverter is left on while plugged into a pedestal, you will not have a working converter.

If that is the case then I think I understand what you have set up and there would not be any harm done if you forget to turn off the inverter except for the lack of battery charging.
 
Henry J Fate said:
Certainly will provide power to all outlets.and I understand tbat but I still wonder what happens when you plug into a pedestal. If the contactor is energized, you will not have the converter charger on so I assume you have the contactor wired to the inverter  output (probably one of the other outlets) That will allow you to unplug from the inverter, plug into a pedestal and you will need to turn off the inverter to allow the converter to do its job. If the inverter is left on while plugged into a pedestal, you will not have a working converter.

If that is the case then I think I understand what you have set up and there would not be any harm done if you forget to turn off the inverter except for the lack of battery charging.
Click to expand...

Yes you are correct that would be the case.  I guess as to why they have made proper transfer switches and such.  My main goal was to protect from forgetting to turn off the breaker to converter. I have purchased some indicator lights now so will wire them in as reminders.  something to on days off when I can't go camping.
 
So maybe you can come up with a method to end that humming which can be pretty annoying. I thought maybe change the contactor to a 12 volt contactor and convert the feed from the inverter back to DC and to the contactor. Sounds crazy but it may work. You would need another contactor though and a small converter to power it but that might be the easiest way to get rid of the humming.
 
I say again a 80-85 volt transformer. a full wave bridge rectifier, a capacitor convert 120 VAC RMS into 120VDC (roughly) (heed not be exact I'd go with 80)

The low voltage side of the transformer goes to the bridge rectifier. the DC side goes to a Capicator How big I'm not going to work out but a common tube radio filter cap should do it.
the cap goes to the Relay (polarity does not matter) but a diode 200 volt at 2 or 3 amps goes across the coil reverse biased.. That's the whole deal. Now it's a DC coil and no hummmmmmmmm
 
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