Intellitec Smart EMS

[W7BE_Bob]

What is the simplest way to disable load shedding? Would removing one of the neutral current sense wires give the desired result? This is for a temporary time and I'm looking for an option other than rewiring each of the 4 circuit hot lines. 

[Scotty Hutto]

Bob,

There are some people on the board more knowledgeable than me, but you should be able to take the cover off your breaker panel and unplug the current transformer from the EMS board. 

[jacwjames]

The power for each of the circuits controlled by the EMS will not work if you remove the neutral.  The easiest thing to do is simply bypass the EMS board.   Take the in & out wire for each circuit an wire nut them together.  Each circuit will then work. 

Just mark each wire so you know where they go.  I normally use tape also with a wire nut just as added protection from the nut coming loose.

 

My EMS was taken out by a lightening strike, I wanted at least one AC unit to work so I bypassed the EMS  board.   Had to replace the board and load meter with a new version which required rewiring with new wiring harnesses.  Not a bad job, just have to follow the directions. 

[Dr4Film]

There is no "easy" method to bypass the EMS Control Board other than what Jim J has explained in the above post.

Why are you wanting to temporarily disable the board in the first place?

[W7BE_Bob]

For clarity I think you're saying the EMS relays are normally open and closed when AC power is initially available. Would removing the sensor from the neutral work since EMS would detect 0A and activate the relays? Just wondering as I would not do that and instead and bypass the relays. In my case the load wire length is adequate to move it to the panel CB. 

I knew someone would ask why. OK I have a reservation at a CG without 50A. The pedestal has 2x 30A plugs and they suggested using the 30/30/50 Y adapter. However they did not know if it was 2x 120V 30A or 120/240V 30A.  I want a plan in place to bypass the EMS if necessary.

I understand the potential safety issues associated with using that adapter but may want to run 2 A/Cs since this is for a summer day. The CG is on the Olympic Peninsula so it's not a given that it will be a warm stay. 

[Dr4Film]

24 minutes ago, W7BE_Bob said:

For clarity I think you're saying the EMS relays are normally open and closed when AC power is initially available. Would removing the sensor from the neutral work since EMS would detect 0A and activate the relays? Just wondering as I would not do that and instead and bypass the relays. In my case the load wire length is adequate to move it to the panel CB. 

I knew someone would ask why. OK I have a reservation at a CG without 50A. The pedestal has 2x 30A plugs and they suggested using the 30/30/50 Y adapter. However they did not know if it was 2x 120V 30A or 120/240V 30A.  I want a plan in place to bypass the EMS if necessary.

I understand the potential safety issues associated with using that adapter but may want to run 2 A/Cs since this is for a summer day. The CG is on the Olympic Peninsula so it's not a given that it will be a warm stay. 

The relays on the EMS control board are NC (aka normally closed) when 50 amp power is first applied to the coach with either 50 amp shore or generator power. If you listen carefully you will hear each of the relays clicking in and the lights on the display will start to light up when this happens. When using only a 30 amp supply pedestal, that's when the EMS board comes into play as the 30/20 amp light will be lit up along with all of the relay lights. Once you start consuming more than 3600 watts of power the relays will begin to OPEN shutting down each device in the selected sequence.

The only way to bypass that function is to bypass each control relay.

Besides, if in fact you plan to use TWO 30 amp supplies, that is a total of 7200 watts of power, 3600 on each leg which is a lot more than the 3600 watts you would be getting from a 30 amp pedestal but less than the 12000 watts of power supplied by a 50 amp pedestal. I wouldn't worry about bypassing the EMS board, just let it do it's work. Plus not sure what your shedding order is compared to mine however the AC's are not the first ones to go.

My shedding order is Hot Water Heater - Rear AC - Washer/Dryer - Front AC.

Edited February 12, 2021 by Dr4Film

[jacwjames]

The previous owner of my coach did something a little different. 

On the bedroom AC unit he rewired the circuit and added a standard outlet to supply power to the AC unit and put a plug on the AC unit feed wire.  By doing this I can run an extension cord in through the window and plug in the AC unit completely bypassing the coaches electrical panel.  The EMS doesn't even know the AC unit is running. 

Pretty cheap solution that you can use anytime you are at a site with only 30 amp provided they have a standard 20 amp plug available also. 

[W7BE_Bob]

My understanding is that 2x 30A plugs that are not 120/240V will result in the EMS selecting 30A and shedding when the total amps on the neutral exceed 30A. If it sees the 240V then the EMS selects 50A as there is no way to tell the difference between a 120/240V 30A circuit and a 120/240V 50A circuit. Is this not correct? But yes once 30A has been exceeded and shedding occurs circuits that are not shedded can draw amps so that the total exceeds 30A. I have several plug circuits that are not on the EMS.

Just clarifying the details as I'll bypass the EMS by moving the wires.

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Besides, if in fact you plan to use TWO 30 amp supplies, that is a total of 7200 watts of power, 3600 on each leg which is a lot more than the 3600 watts you would be getting from a 30 amp pedestal but less than the 12000 watts of power supplied by a 50 amp pedestal.

 

[W7BE_Bob]

2 hours ago, jacwjames said:

The previous owner of my coach did something a little different. 

On the bedroom AC unit he rewired the circuit and added a standard outlet to supply power to the AC unit and put a plug on the AC unit feed wire.  By doing this I can run an extension cord in through the window and plug in the AC unit completely bypassing the coaches electrical panel.  The EMS doesn't even know the AC unit is running. 

Pretty cheap solution that you can use anytime you are at a site with only 30 amp provided they have a standard 20 amp plug available also. 

I installed a variation of the above. My rig has a 20A plug in the engine room to plug in thee engine block heater (yeah my cheap Monaco does not have a dash switch to activate the block heater). I added a circuit that can use this plug or and extension cord with 2 interior plugs in the closet and the front. The basic use of this circuit is for 2 ceramic heaters that gets it's power from the block heater circuit or an external extension cord. The front plug is under the CB panel so I could adapt a A/C circuit to use it.

Some of Monacos wiring both AC and DC definitely show cost cutting measures. One for example is the inverter 20A AC plug output circuit which first goes to a GFCI. And then on to 17 other plugs throughout the RV. This is not a typo - 18 total plugs on that circuit.

[Larry Laursen]

Bob,

Back in 2002 we were traveling with the friend who had a 2001 Scepter that didn't have the generator sense wire connected to the EMS.  Thus, the EMS thought it was on 30 Amp.  As I recall I just bypassed the EMS relay for the second A/C unit by moving the one wire.  The A/C is the main power draw so he still had protection for the electric water heater and an A/C.  I would also change the setting on the inverter to 30 or 15 Amp for charging.  You will be connected to shore power for awhile so a slower charge rate should be okay.

48 minutes ago, W7BE_Bob said:

My understanding is that 2x 30A plugs that are not 120/240V will result in the EMS selecting 30A and shedding when the total amps on the neutral exceed 30A. If it sees the 240V then the EMS selects 50A as there is no way to tell the difference between a 120/240V 30A circuit and a 120/240V 50A circuit. Is this not correct? But yes once 30A has been exceeded and shedding occurs circuits that are not shedded can draw amps so that the total exceeds 30A. I have several plug circuits that are not on the EMS.

Just clarifying the details as I'll bypass the EMS by moving the wires.

Bob,

Yes, you have the correct analysis of the EMS above.  As I said in another post just bypass the EMS feed for one A/C by moving one wire to come directly from the CB.   The 8KW inverter equipped generators have two 30 amp circuits at 120 and no 240.  Thus, there is a 12 volt supply wire that comes from the generator to the EMS to by pass it when the generator is supplying power to the coach.

[W7BE_Bob]

Thanks Larry and everyone else who helped on this thread.

My 04 Endeavor had a 7500W gen with 2 x 120V circuits. ie 62A total. Monaco uses a special 4 wire cable with the neutral wire one size larger. This went from the gen to the ATS to the CP panel. 

[jacwjames]

The one problem with bypassing the EMS on a circuit that you intend to use, an AC unit, there still may be a problem with shedding.  If I'm not mistaken the EMS senses total load being used and when you exceed the 30 Amps it will start shedding loads until it drops below the 30 amp level.  So even if you bypass one AC unit it may move to the next one to shed load to get below 30 AM. 

On my coach the loads that are controlled by the EMS are Front & Rear AC, Water Heater, and Washer/dryer.  I can easily control the Water heater by turning it off, same with the Washer and dryer.   If I leave both AC's they both may run depending on total load but usually one will run all the time. 

If for some reason I am using more power and say I microwave something, the AC may shut off. 

Even if you bypass the EMS with the one AC unit it will run all the the time and the other may or may not run depending on total load.  But if you are using more power there may be a chance you overload the 30 amp and the breaker may trip.  

The only way to get both AC to run is to completely bypass the main service panel that provides power to one AC. 

[tcbrow]

I would think that the 30/30/50 Y adapter will work as intended. 50 amp service supplies 2 120v lines. They never connect to make a 240v line. Do a continuity check on the Y adapter (between each 30 amp and the 50 amp) and you will see that the 50 amp outlet has 2 separate 120v connectors.

[jacwjames]

Agree, as long as they are L1 & L2 separate lines. 

[Scotty Hutto]

I’m hoping @Larry Laursen or @Frank McElroy can straighten me out here, but this is my understanding from the Intellitec manual:

“Energy Management is only enabled if 240 VAC Service is not available. When connected to 240 VAC Service, the Energy Management features of the unit are disabled and the unit switches all controlled loads “ON”.

The main neutral line is routed through the magnetically coupled current sensor, which measures the current flowing through the neutral line. This is the total amount being drawn by all the 120 volt appliances in the RV when the available power service is 120 VAC. When this current exceeds the "shore" service rating of 30Amps (20Amps if the threshold has been set lower or the generator service rating and 240 VAC service is not available, the will turn off the controlled loads in an effort to bring the total current to the limit of the incoming service”

So... why wouldn’t disconnecting the current sensor (CT, or current transformer) disable the EMS? On my board it has a small connector that will allow me to disconnect the CT. 

Theoretically you could mount a small DPDT switch to enable or disable energy management... at your own risk, of course.  It is there for a reason, but Bob’s situation seems like one that would merit that.  
 

It seems a very simple solution to @W7BE_Bob’s problem, or am I missing some important point? (I probably am, but wanted to ask...)

[jacwjames]

Yes, that may work unless the EMS has some sort of logic that doesn't let it work if it senses no load at all.  This would be the ultimate KISS solution. 

If some one is brave enough they could give a try. 

The EMS board does have some protections built in.  When I installed my upgrade I made a mistake on the wiring and when I plugged it in it didn't work at all.  Had to start from scratch, figure out what I did wrong and made the correction.  No harm to the system.   

[Larry Laursen]

Scotty,  Yes to my knowledge you are correct The Intellitec EMS senses the current on the main neutral line in the 120 volt distribution panel and is disabled when it see 240 volts between L1 and L2.  When you are on a normal 50 amp 240 volt shore connection the current going through the neutral is the difference of the currents in each leg.  That is; if L1 is using 20 amps and L2 is using 10 amps the neutral is passing 10 amps back to the campground distribution panel.  The 8KW generators are wired so that the neutral carries the sum of the current in each leg which would be 30 amps in the case above.  When you are connected to a 120volt 30 amp RV outlet the neutral carries the sum as with the generator.  The EMS will allow about 80% or 24 amps over an extended time.  The EMS needs 12 volts DC for its power and logic plus it must sense 120 or 240 volts to turn on.  The neutral wire from the generator is larger #6AWG to carry the total amperage which can be 60 amps.  Line 1and 2 are #8AWG from the generator.  If you have a 10KW or 12KW generator, they are 240 volt generators and the system works as if on 50 amp 240 volt shore power.  The normal 50amp RV service cord is 3 #6AWG plus one #8AWG for the ground.

So yes if you bypass one of the A/C's it will still shutdown the other items controlled by the EMS if the total load exceeds 30 amps for a short period or 24 amps for a long period.  If you bypass both A/C's then the EMS will shut down the water heater and washer dryer in most coaches.  Now if you disconnect the current sensor than you have no protection.   I don't know if an open sensor will disable the EMS or simply make it inoperative and not allow any of the loads to operate.  The coil in the sensor has some resistant and may be sensed by the EMS circuit for safety reasons.  I can't find anything in the manual about this.

You can supply 12 volts to the generator input connection and disable the EMS as is done for the 8KW Onan generator.  There is a wire than comes from the generator hour meter to the EMS.  If you are interested the installation and operation manual is attached

Intellitec MDL750 EMS.5300684.000.pdf

[Frank McElroy]

Larry - I couldn't have explained it any better.  Great job.  I added the service manual you posted to the Download File section under electrical.

 

[k7jv]

Just to jump to a quick "Plan B", on the Olympic peninsula it is likely that you won't need even one A/C.  We are almost always able to keep our '06 Dynasty pretty comfortable with only one running.  In fact it is only on days where it gets above 80 or 85 that we even have to run two.  It takes the mid-90's before we need all three.  When we are on 30 amp service, we'll leave only the front one on during the day, and then shut the front one down and leave the bedroom one in service at night.  It would be a very rare day that you would need two A/C's up there, and even if you did get a truly "hot" one for them, it wouldn't be for more than a couple or three hours.  It's BEAUTIFUL up there!!  In Sequim, in mid-July, the average high is 72 and the average low is 55.  The 90th percentile high is 80 and the 90th percentile low is 52.  Sequim is in the "banana belt" of the Olympic peninsula.  You'll have a fantastic time up there, and you will be much more likely to run your heat than you will your A/C.  Don't worry about your load-shedding and just ENJOY!!!

[Scotty Hutto]

Out of intellectual curiosity, I was at the coach today and decided to test my theory on disconnecting the current transformer of the Intellitec EMS. Before starting I checked the amp draw (battery float charge and lights on)

Opened the breaker panel and disconnected the current transformer...

 

 

checked amp draw...

 

No alarms or shutdown.  I cut on the electric water heater to test loading and it stayed at zero. 

So... this worked.  Your mileage may vary and please remember, those amperage draw limits are there to protect you, the coach electrical system, and the power source feeding your coach. Disabling them for a short duration in an unusual situation might be ok, but long term you might inadvertently overload circuitry and cause a fire or other damage.  PLEASE be careful!

 

[Dr4Film]

Your EMS Display shows an unusual shedding order compared to my coach.

The two 12 VDC are on top being first followed by the typical sequence, Water Heater - Rear AC - Washer/Dryer - Front AC

[jacwjames]

Thanks Scotty, Now we know there is a quick option to disable. 

If I were going to do this long term I'd install some sort of switch to over ride it.  I would also record the typical amperage of the AC1 &2 to know if I could run them on 30 amp.  One thing to remember is that if you have lower voltage your amperage will increase which may limit your ability to run both AC's. 

[W7BE_Bob]

Clarification: If you are connected to a single 30A plug with an adapter there is NO need to disable load shedding and you can't exceed 30A period. If on the other hand you use the 30/30/50 Y adapter and the power is NOT 120/240V then you have 2 30A circuits or 60A available. You CANNOT OVERLOAD either circuit since its 30A breaker will trip. Howerver in this type of non compliant setup the neutral carries the sum of the hot leads and hence is overloaded if you draw 51 to 60A. But my understanding is that the EMS will detect non 240V and limit load shedding to 30A total which is why I started this thread about disabling the EMS. This was a result of a CG telling to use the Y adapter with their 2 30A plugs in the pedestal.

If however the the pedestal is wired as 120/240 30A (known as split-phased) then the neutral carries the difference of the 2 hots or 30A maximum on the neutral lead. And as a result you have 30A available on each hot leg or 60A total.

There are safety concerns using the Y adaper, however that have not been covered.

[W7BE_Bob]

Y adapter safety concerns: The biggest concern is that ONLY one CB will trip leaving 120V available. This can be misleading since normally ALL 120V power is removed due to the use of a dual CB breaker.

Another concern is overloading the adapter or pedestal neutrals when drawing from 30 to 50A on a non 240V pedesal. No issue with the RV 50A wiring. However the adapter 50A neutral is connected to both 30A plug neutrals and the current for each neutral is controlled by the impediance of each neutral and in this case the current may not be evenly spilt 50-50. For example one neutral prong is more tarnished and hence higher impediance and so one neutral is carrying 40A and the other 5A. This possible overload applies to the adapter and neutrals in the pedestal and may even apply to further upstream depending upon how the pedestal is wired.

These 2 concerns are one reason CGs don't allow the use of the Y adapter. They usually don't understand any of the above. I was surprised when a CG suggested I use the Y adapter.

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