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F438921

2005 42 ft Monaco Dynasty, shore power cuts in and out

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We were camping last weekend on the hottest week of the year and the ATS (auto transfer switch) kept kicking out every 30-40 seconds but only with the a/c on. The coach has a 50 amp system, three a/c units and was plugged into a 30 amp shore power plug in. I do not try to run them all on 30 amps its either the front or the back. I just ended up shutting the a/c's off and everything else seemed to work normal. I started the Onan 10k generator and they all ran perfectly fine with no issues. When I got home I plugged the shore power cord into my garage 15 amp plug and the a/c came on and the ATS was cutting in and out exactly the same as it did when it was plugged into the 30 amp service because I had forgotten to shut the a/c off after driving home and running the generator. So in my eyes it seems to be doing exactly the same thing plugged into a 15 amp service as it did when plugged into the 30 amp. My surge protector showed that there was 104 volts at the campground plug in and I took the cover off the ATS box and the voltage from L1 to L2 was 104 and L2 to L3 was the same while at the campground. So I'm looking a little advise here if anyone can help me, I'm a licensed automotive tech so I do have a good understanding of how stuff works. If I had to guess its only getting 15 amps to the coach???

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What is the BTU rating and make of the different Roof AC units?  Could you run all 3 units in fan mode only?

You did not mention if the Circuit breaker trips when connected to the 15 amp circuit, a 20 amp circuit breaker should can handle One AC unit, IF the battery charger is running at the float level. The current requirement for the charger should be 3 to 4 amps in float mode. A good circuit breaker would be working real close to the trip point though.

A 11,500 BTU AC unit would require 32 amps at full load at 104 volts. What readings did you get at the shore  power riser using a multi meter. The same unit at a line voltage of 120 volts would require 28 amps.  

What is the resistance reading across the shore power ATC contacts for the L1 and the L2 circuits?   What is the condition of the ATS L1 and L2 wiring terminals in the ATS boxes and the ground connections between chassis and ground buses.  

Check the condition of all the connections at both ends of the shore power cable?  You might be able to barrow a known good 50 amp shore cable using the 30 to 50 amp adapter you used at the camp sight.

   You did mention cover off the ATS box and the voltage from L1 to L2 was 104 ?? and L2 to L3 was the same while at the campground.  104 volts on both L-1 and L-2 measured to neutral or ground?

The other connections to check - are the neutral, Common and circuit breaker connections in the Ac power panel.  I know that you mentioned that everything worked well when the generator was running, but things do loosen up over time and a number of coach owners include checking them as part of their yearly maintenance program.

All AC Power sources disconnected or off while checking the ac power connections !! 

Rich.

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At 10,000 watts you had 41.6 amps available on each leg, L1 and L2, that is of course on the generator. Plugged into 50 amp service, you would have 50 amps each leg, and of course my colleagues would correct me and say that is 100 amps, but still 50 per leg. The generator is producing 83.3 total. Now, one AC unit should run OK if not too many other appliances are being run at the same time unless there is a problem with the unit. All that said, 104 voltage is very low, and I did read anywhere in your op what the voltage was at the cg pedestal, but since the same thing happening, I would begin to suspect that there may be a problem with the pigtail that you use to reduce from 50 amps to 30. If it were me, I would do as Rich suggested to be sure to retighten all lugs inside the ATS and all other places that are possible. But I would also seek to find a known good working 50 amp shore connection to plug into to make sure all is working well with the shore 50 amp setup. There are course two sets of contacts within the ATS, one may be getting weak, and of course that one would be the shore power side, but again 104 is too low voltage and it may well be kicking out as a result of the low voltage.

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My suspicion is that the ATS is doing its job. As voltage drops the amps go up. Running an a/c unit on 104v will increase the amperage draw and quite likely trigger the ATS to cycle like it did. When you got home and forgot to turn off the a/c it sounds again like the ATS did its job and kept you from overloading the 15-amp circuit.

Any way you can test this on a properly built 50-amp connection?

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22 hours ago, DickandLois said:

What is the BTU rating and make of the different Roof AC units?  Could you run all 3 units in fan mode only?

You did not mention if the Circuit breaker trips when connected to the 15 amp circuit, a 20 amp circuit breaker should can handle One AC unit, IF the battery charger is running at the float level. The current requirement for the charger should be 3 to 4 amps in float mode. A good circuit breaker would be working real close to the trip point though.

A 11,500 BTU AC unit would require 32 amps at full load at 104 volts. What readings did you get at the shore  power riser using a multi meter. The same unit at a line voltage of 120 volts would require 28 amps.  

What is the resistance reading across the shore power ATC contacts for the L1 and the L2 circuits?   What is the condition of the ATS L1 and L2 wiring terminals in the ATS boxes and the ground connections between chassis and ground buses.  

Check the condition of all the connections at both ends of the shore power cable?  You might be able to barrow a known good 50 amp shore cable using the 30 to 50 amp adapter you used at the camp sight.

   You did mention cover off the ATS box and the voltage from L1 to L2 was 104 ?? and L2 to L3 was the same while at the campground.  104 volts on both L-1 and L-2 measured to neutral or ground?

The other connections to check - are the neutral, Common and circuit breaker connections in the Ac power panel.  I know that you mentioned that everything worked well when the generator was running, but things do loosen up over time and a number of coach owners include checking them as part of their yearly maintenance program.

All AC Power sources disconnected or off while checking the ac power connections !! 

Rich.

Rich, I don"t know the a/c BTU's and I never tried to run fans only, no breakers kick out, just the ATS keeps kicking in and out on 15 or 30 amp, not sure what the L1 & L2 resistance is. I did try another 30 amp plug in at another campground which had 110 volts to no avail. I haven't checked the resistance across the points but 104 volts was to the neutral as I believe thats what L2 is because when I was online it told me to test it from L1 to L2 then L2 to L3. I did check all connections in the ATS box and they are all tight. Now are you saying to check the circuit breaker connections inside the RV in the breaker boxes? I got another 50-30 amp adapter to try to no avail, I also measured resistance of my shore power cord and got 2.4 ohms on all the cables, so thats good to. 

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I had erratic reading on my incoming power and found that I had a bad plug on my power cable. Replaced the plug and have had no more problems. One thing I saw on the plug was that the blades seemed to be loose. Worth a check.

Herman 

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2 hours ago, F438921 said:

Rich, I don"t know the a/c BTU's and I never tried to run fans only, no breakers kick out, just the ATS keeps kicking in and out on 15 or 30 amp, not sure what the L1 & L2 resistance is. I did try another 30 amp plug in at another campground which had 110 volts to no avail. I haven't checked the resistance across the points but 104 volts was to the neutral as I believe thats what L2 is because when I was online it told me to test it from L1 to L2 then L2 to L3. I did check all connections in the ATS box and they are all tight. Now are you saying to check the circuit breaker connections inside the RV in the breaker boxes? I got another 50-30 amp adapter to try to no avail, I also measured resistance of my shore power cord and got 2.4 ohms on all the cables, so thats good to. 

Well, you have eliminated some items - like the shore power cable and the 50 to 30 amp adapter.

         Regarding the coach end connections, the connection resistance between the CG Riser end  and the point where the coach end connects to the coach ATS should also read real close . I also measured resistance of my shore power cord and got 2.4 ohms on all the cables, so that's good to.  

      Your coach  is equipped with a power core real !  For it to work there needs to be a slip-ring stile connection between the real and the connections that attach to the Wires going to the ATS.  What kind of reading do you get ?  or are the readings you posted  between the Riser  end and the ATS?

Regarding the Circuit breakers and the Neutral / ground buss bars do need to be tight.   The power coed feeds the L-1 and L-2, supply 50 amp main circuit beakers in the power panel and those breaker terminals need to be tight ! 

The EMS System PDF file shows a typical wiring drawing for a 50 amp service on page 15.

              Note ! Most coaches of the model year you own have an EMS installed - the oldest being the 700 series up to the 900 series. 

Hope the additional information clears up the wiring path for the 120 volt systems, they do very some from model to model and year to year.  

Remember all it takes is a loose connection, damaged wire or a damaged transfer switch to limit current flow. 

Rich.

Typical_ATS_setup_for_S._P._and_gen_power_power_panel_120-feed.jpg

Intellitec EMS 800 system.pdf

EMS Operation.pdf

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You stated that your coach is a 50 amp unit, therefore L1 should be showing 110 to neutral or ground. With a properly wired adapter, L2 should read 110 to neutral or ground, 0 voltage should be read from L1 to L2, in a 50 amp unit, the unit is expecting 240 volts from L1 to L2, the adapter takes 110 from the hot leg of shore power and splits this to send 110 to each L1 and L2. If you are testing L1 to L2, then your meter should be showing 0 volts that way. If you unplug from shore power, and the generator off, with the adapters in place on the shore power cord, then you should see 0 ohms from L1 to L2, because it is a direct short. If you are finding voltage from L1 to L2 as you stated, then the adapter or the pedestal is wired incorrectly. The above test should be performed inside the ATS. If testing 30 amp service at the CG pedestal then there is a hot leg, 110/120, a neutral leg, and a ground leg, you should actually be finding, hot to neutral 110, or hot to ground 110, and zero neutral to ground. I sure hope this helps in understanding what to expect.

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On 2018-08-14 at 7:47 AM, richard5933 said:

My suspicion is that the ATS is doing its job. As voltage drops the amps go up. Running an a/c unit on 104v will increase the amperage draw and quite likely trigger the ATS to cycle like it did. When you got home and forgot to turn off the a/c it sounds again like the ATS did its job and kept you from overloading the 15-amp circuit.

Any way you can test this on a properly built 50-amp connection?

Well I can go to a campground just outside of town and plug it in to see what happens.

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11 hours ago, F438921 said:

Well I can go to a campground just outside of town and plug it in to see what happens.

That is a great idea!

 

On ‎8‎/‎14‎/‎2018 at 7:47 AM, richard5933 said:

My suspicion is that the ATS is doing its job. As voltage drops the amps go up. Running an a/c unit on 104v will increase the amperage draw and quite likely trigger the ATS to cycle like it did. When you got home and forgot to turn off the a/c it sounds again like the ATS did its job and kept you from overloading the 15-amp circuit.

Actually the ATS is not designed to kick out in the event of an overcurrent condition. it's only job is to switch from shore power to the generator or whatever source of power that you may want to switch to, could be an inverter or a different pedestal. The likely hood that it is kicking out is probably due to the fact that there is not enough current to keep the relay engaged. If there is not enough current available, then a fuse/cicuitbreaker will not blow or trip because it is looking for an over current event. What will happen in the case of under current is that devices in this condition will not work properly and or can actually burn out the device that is subjected to such a condition, and in this situation, better that is a relay as opposed to an air conditioner, much less costly to replace a relay. 

A loose screw, a bad wire, or a bad plug, or receptacle or a poor ground connection is usually the only cause for an under current condition. When I supervised a large store chain, many years ago, I had one store that would run all lights within the store fine, but when AC or walkin coolers were activated, none of these units would even come on, again lights not affected. All circuit/breakers checked out ok, still no coolers would work. I called on the power company for their help, and they sent their repair crew who immediately changed out the connectors that connected company power to store connection, viola, the coolers started right up and the power bill dropped $700.00 per month in that store. Moral is that a loose connection can happen at any time or any place within the confines of the power source.

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On 2018-08-13 at 11:18 PM, DickandLois said:

What is the BTU rating and make of the different Roof AC units?  Could you run all 3 units in fan mode only?

You did not mention if the Circuit breaker trips when connected to the 15 amp circuit, a 20 amp circuit breaker should can handle One AC unit, IF the battery charger is running at the float level. The current requirement for the charger should be 3 to 4 amps in float mode. A good circuit breaker would be working real close to the trip point though.

A 11,500 BTU AC unit would require 32 amps at full load at 104 volts. What readings did you get at the shore  power riser using a multi meter. The same unit at a line voltage of 120 volts would require 28 amps.  

What is the resistance reading across the shore power ATC contacts for the L1 and the L2 circuits?   What is the condition of the ATS L1 and L2 wiring terminals in the ATS boxes and the ground connections between chassis and ground buses.  

Check the condition of all the connections at both ends of the shore power cable?  You might be able to barrow a known good 50 amp shore cable using the 30 to 50 amp adapter you used at the camp sight.

   You did mention cover off the ATS box and the voltage from L1 to L2 was 104 ?? and L2 to L3 was the same while at the campground.  104 volts on both L-1 and L-2 measured to neutral or ground?

The other connections to check - are the neutral, Common and circuit breaker connections in the Ac power panel.  I know that you mentioned that everything worked well when the generator was running, but things do loosen up over time and a number of coach owners include checking them as part of their yearly maintenance program.

All AC Power sources disconnected or off while checking the ac power connections !! 

Rich.

Rich I tested the resistance  across the L1 L2 and L3 circuits when closed and it was zero ohms, all the wires look good inside the box, both ends of the shore power cable are good and the resistance is also good, I bought a new 50-30 amp adapter to try as well, the 104 volts was measured using the neutral wire, I removed the a/c panel box covers and checked all connections and they were tight. 

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1 hour ago, F438921 said:

Rich I tested the resistance  across the L1 L2 and L3 circuits when closed and it was zero ohms, all the wires look good inside the box, both ends of the shore power cable are good and the resistance is also good, I bought a new 50-30 amp adapter to try as well, the 104 volts was measured using the neutral wire, I removed the a/c panel box covers and checked all connections and they were tight. 

        Things tend to look good, but there is an issue somewhere !  The Key here might be to divide and conquer. 

Thinking that if one was to remove the ATS control voltage so they do not close (in this case everything between the generator and its ATS works, if I'm reading your post correctly)that leaves only the shore power circuit. 

Removing the coil voltage from the Shore Power ATS and reading the voltage level at the line input terminal.  No drop in voltage ? then energize the coil with minimum load(might disable the inverter / charger) what changes?   Then enable the Inverter / charger, what is the voltage reading?  Also, what is the voltage reading at the EMS Panel?

Finding a difference between the ATS voltage and the EMS system - puts the problem after the ATS and between it and the Main power panel and the Ems. 

Post any differences or if there is no difference.  We will go from there.  Sometimes the little things can drive one bonkers.

Rich.

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Well after going through and checking every wire connection for looseness, in the ATS and in the breaker boxes and then blowing out the ATS relay contacts I then went and plugged into a 50 amps service everything worked fine. I then plugged into a 30 amp service and everything was good but the rear a/c would turn on and off due to too much load on the 30 amp circuit which is normal but if I ran the front or rear a/c separately it worked just fine. I'm not sure what I did to fix the problem but I think blowing out the relay fixed it as there must have been something in the contacts, either that or it temporarily fixed itself and the problem will come back again. I watched the monitor to see how much leg 1 and leg 2 were drawing for amperage and I'm not sure how things are split up and what runs on what. I have taken some pictures to show you guys. I thought the front two a/c units ran on leg one and the rear on leg 2 but I"m not sure now.IMG_7062.thumb.jpg.97bc006474549371f4c60675ecb90944.jpgIMG_7063.thumb.jpg.b8897de5506fe6f5f6912306fe796bf5.jpgIMG_7064.thumb.jpg.7896d5de1db87b3a24f9bf5923e0a4f2.jpg

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Thanks for the update !  Things working is always good. Readings, look like you where connected to 50 amp service ?  Did you use the 30 to 50 amp adapter at any point while taking the pictures?

Well after going through and checking every wire connection for looseness, in the ATS and in the breaker boxes and then blowing out the ATS relay contacts I then went and plugged into a 50 amps service everything worked fine. I then plugged into a 30 amp service and everything was good but the rear a/c would turn on and off due to too much load on the 30 amp circuit which is normal but if I ran the front or rear a/c separately it worked just fine. I'm not sure what I did to fix the problem but I think blowing out the relay fixed it as there must have been something in the contacts, either that or it temporarily fixed itself and the problem will come back again. I watched the monitor to see how much leg 1 and leg 2 were drawing for amperage and I'm not sure how things are split up and what runs on what. I have taken some pictures to show you guys. I thought the front two a/c units ran on leg one and the rear on leg 2 but I"m not sure now. I will look and see if I can find a 120 volt power wiring diagram for your coach's power distribution.

Think the fact that both L-1 and L-2  have between 117 and 114 volts in all the pictures, that they where taken when you where connected to 50 amp riser?

The other item that stands out is The Leg 2 readings - Rear AC on and this leg reads 25.3 to 26.6 amps when the Rear AC units are on. With the Rear AC off Leg - 2 is still drawing 13.1 amps. The key now is to find what is drawing 13 plus amps with the rear AC's off - I have run into this reading at least one other time. NOW remembering what caused this reading. 

Rich.

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Blowing out the ATS was a good move, I have seen ants or some other insect get lodged onto the contacts and cause similar problems. The bottom picture is not representative of 30 amp service, L1 is showing 13.6 amps, while L2 is showing 26.6 amps, that's a total of 40.2 amps. Is it possible that at home you are running a 30 amp double pole breaker feeding a 50 amp receptacle?

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F 438921, This is a link to get a copy of the Owners manual for your coach if you do not have one.

https://www.monacocoach.com/resources/media/manuals/2005_Dynasty.pdf

Section 8,  Page  347 has a picture of the mail and sub power circuit breaker panels - what is on L-1 and L-2. 

The Current reading on the L-2 side might be the Water heater mentioned by Richard, I'm Thinking Engine block heater ?

Need to keep checking into an electrical drawing.

Rich.

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3 hours ago, DickandLois said:

Thanks for the update !  Things working is always good. Readings, look like you where connected to 50 amp service ?  Did you use the 30 to 50 amp adapter at any point while taking the pictures?

Well after going through and checking every wire connection for looseness, in the ATS and in the breaker boxes and then blowing out the ATS relay contacts I then went and plugged into a 50 amps service everything worked fine. I then plugged into a 30 amp service and everything was good but the rear a/c would turn on and off due to too much load on the 30 amp circuit which is normal but if I ran the front or rear a/c separately it worked just fine. I'm not sure what I did to fix the problem but I think blowing out the relay fixed it as there must have been something in the contacts, either that or it temporarily fixed itself and the problem will come back again. I watched the monitor to see how much leg 1 and leg 2 were drawing for amperage and I'm not sure how things are split up and what runs on what. I have taken some pictures to show you guys. I thought the front two a/c units ran on leg one and the rear on leg 2 but I"m not sure now. I will look and see if I can find a 120 volt power wiring diagram for your coach's power distribution.

Think the fact that both L-1 and L-2  have between 117 and 114 volts in all the pictures, that they where taken when you where connected to 50 amp riser?

The other item that stands out is The Leg 2 readings - Rear AC on and this leg reads 25.3 to 26.6 amps when the Rear AC units are on. With the Rear AC off Leg - 2 is still drawing 13.1 amps. The key now is to find what is drawing 13 plus amps with the rear AC's off - I have run into this reading at least one other time. NOW remembering what caused this reading.  Well Rich I was plugged directly into a 30 amp service  when I took the pictures before the rear a/c cut out from being plugged into a 30 amp. 

Rich.

 

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2 hours ago, kaypsmith said:

Blowing out the ATS was a good move, I have seen ants or some other insect get lodged onto the contacts and cause similar problems. The bottom picture is not representative of 30 amp service, L1 is showing 13.6 amps, while L2 is showing 26.6 amps, that's a total of 40.2 amps. Is it possible that at home you are running a 30 amp double pole breaker feeding a 50 amp receptacle? I was plugged directly into a 30 amp plug but there is also a 50 plug right beside the 30 amp one so I'm not sure how its fed.

 

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28 minutes ago, kaypsmith said:

L2 is definitely carrying a pretty large load from something, I suspect that L2 is supporting the inverter/charger and who knows what else.

Well thats what I was kinda thinking because all that stuff has to get its power from somewhere.

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3 hours ago, richard5933 said:

A 1500-watt water heater element would draw about 12 amps when running. Was every breaker turned off except the a/c when making this test?

No I have the aqua hot heater off.

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If the coach is plugged into 30-amp service, then the current is coming from somewhere. Perhaps the inverter is automatically supplying the deficit from battery?

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44 minutes ago, richard5933 said:

If the coach is plugged into 30-amp service, then the current is coming from somewhere. Perhaps the inverter is automatically supplying the deficit from battery?

Most likely, after studying the manual that Rich supplied, that makes sense.

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