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Old 05-04-2010, 08:37 PM   #1
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Power management system load question

Hi - first time on a MH forum so I hope I'm in the right place. Motorhome is a 2000 Itasca Suncruiser 35U. The documentation for the power management system says some sort of load averaging over a 3 hour period is performed and a comparison of the average is made to whatever 80% of the total amps max is (30 amps when plugged x .80 = 24 amps in in my case) . I'm thick sculled and neither the description nor the example really explained to me what is going on here. Isn't the threshold going to be changed to 24 amps after 3 hours regardless of any average? Also, I didn't find any documentation on the shedding table sequence. Does anyone know what it is or how I can find out? Thank you for any help.
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Old 05-04-2010, 09:14 PM   #2
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Ralphie,

Welcome to the forum. Go on to Intellitec's website. You can find the instruction manual for your unit. I found that it had a good description of its operation.

It will be an Acrobat PDF file. You can download and save it for printing whenever you want.

Good Luck

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Old 05-05-2010, 05:29 AM   #3
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The shedding sequence is the same as the panel shows starting from the top in order. I believe water heater, 2nd AC, refrig, etc., depending on what your coach is loaded with.
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Old 05-05-2010, 06:33 AM   #4
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Than you both. I should have signed my post with my name - Patrick. Ralphie (my user name) is actually my dogs name. The Intellitech online manual is the same as what I have in my MH. Maybe if you could tell me what would happen for each of these cases. Let's say I pull 25 amps for 1.5 hours, then 20 amps for 1.5 hours. The average is 22.5 amps (under 80% of the total load limit). If I pulled 30 amps for 2.5 hours and 25 amps for .5 hours, the average would be 29 amps (over 80% of the total load limit). My confusion is this - If the limit is going to be dropped to 24 amps, or 80% of the max after 3 hours anyway, what difference does averaging make?
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Old 05-05-2010, 01:39 PM   #5
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Hi Patrick,

Agreed, it’s just a tad confusing. Think ‘circuit breaker’, that is what the Intellitec is designed to protect. Well, ‘protect’ probably isn’t the right word. More to prevent it from tripping. Circuit breakers are usually magnetic and thermal. Magnetic in that they are designed to trip if the current spikes high as in a short circuit. Thermal in that they have a trip curve based on the time a given current is passed through the circuit breaker. The current heats a small element that warms a thermal element that makes the breaker easier and easier to trip the longer the current is applied and the higher the current is.

You can look up the specs for any given breaker on line but as a general rule, all breakers will pass rated current continuously and usually something like 105% or 110% continuously at a given ambient temperature. This is done because sometimes the breaker may be installed on a pedestal (RV?) with the sun beating down on it in the middle of summer and this increase in ambient temperature needs to be at least partially accounted for. The opposite is true for winter. At 0 degrees, a 30 Amp. breaker may handle 40 Amps. without tripping.

The Intellitec is designed to keep the load current below the pole’s 30 Amp. (or 20 Amp.) breaker. The specifics of how it does this is where the confusion enters the picture. Here is the section in question:
Document 00-00633-000 and 00-00634-000
3 HOUR AVERAGING
The R.V.I.A. (Recreational Vehicle Industry Association) in conjunction with the N.E.C. (National Electrical Council) have established rules regarding the rating of electrical systems and the use of energy management systems. One of these rules requires that, if an energy management system is used, the average total load current for the system over a 3 hour period be limited to 80% of the service rating. For that reason the PowerLine EMSTM calculates the average running current for the system and, if it exceeds 80% of the service rating, the EMS sheds loads to reduce the average current below that limit. For example, if a system operating under 120 VAC, 30 Amp service has been running at the 30 Amp limit for three hours, the EMS will change its shedding threshold to 24 Amps and turn off loads until the 24 Amp limit is attained. If the user selects the 20 Amp service mode this limit will translate to 16 Amps. Because the EMS calculates a running 3 hour average, if the average load current drops below the limit, the system will restore power to loads based on their impact on the limit. If the system is in the Averaging mode the decimal point at the lower right corner of the Load Meter display on the Display Panel will illuminate.
My guess is that somewhere along the way, the R.V.I.A. and the N.E.C. realized the error of their ways and decided to do away with the 80% requirement. This took effect sometime around or before 2000 and the control was redesigned with new part numbers. Since your unit is a 2000, are you able to determine which control is installed? If it’s the new one, forget the 80% and just use 30 Amps. If it has the old control board installed, then the 80% paragraph above applies. If this is of concern to you, you could probably replace the board but I wouldn’t worry about it since there is little impact on normal use. Holding right at 30 Amps. for 3 hours is a quite a trick, summer or winter. This is the document to use if your control is the 2000 version:

Document 00-00740-100 and 00-00757-000

The best way to determine the shedding order is to increase your loads to over 20 Amps. and then switch the Intellitec display to 20 Amp. Try to control the loads to get 21 Amps. and then verify that the load that the display indicates is actually the load that is shed. Then increase the load back up to 21 Amps. and check the next item (borrow a couple of high-medium-low electric heaters). Easiest is to have the device running so you can hear or see it’s power removed. If you can’t see or hear it, then use the breaker and the Amp. meter on the display to prove that that’s the correct load. You probably will have no disparities show up. Not so with the 2004 model years! The control was redesigned and Winne didn’t get it right.

The answer to your original question therefore is: You must run more than 24 Amps. for at least 3 hours for the limit to kick in, in the first place. I can’t imagine both AC compressors or the HW heater running continuously for 3 hours and if the load were to just tip 31 Amps., then the loads would start shedding which would drop the average back down anyway. I can’t specifically answer the question of ‘is the 24 Amps. a fixed threshold or does it change depending on weather the average is 30 … 25 Amps. over the average 3 hours. And if the average drops down after activating the 80% is the threshold then increased to 25 … 30.

I don’t think so, but without conformation from Intellitec…. So, under normal situations, the 80% thingy will have no effect on you. If anyone has seen this situation occur, please let us know the specifics that caused the high steady current. Hope this helps, if not let us know.
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Old 05-05-2010, 08:31 PM   #6
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Thank you, you've given me quite an education that is not in the manuals. I believe I have the 80% after 3 hour averaging model - that's the document that came with the MH. I'm not necessarily concerned with lowing the amp threshold after 3 hours unless my air conditioning is going to be shed while I'm not in it, but my dog is - that would be be my only concern which is why I'm trying to understand it (and because it's the only thing in all the MH documentation that I don't completely understand - that bugs me). I had the air conditioning looked at when I first bought it because I could swear it was warm inside when we returned to it one day after being out for many hours - they found nothing wrong and I have since not had aproblem. I might have had something set wrong (maybe even the thermostat - my first digital one) because I know I hadn't read any of the documantation yet and just assumed everthing worked like my 94 Bounder did (no EMS - just like a house). I'll call Intelitech if I find I can't get on with my life without knowing exactly how this thing works. But I sure won't let it keep me and my family from having a great time motorhoming as we have with this and our previous motorhome. Thank you for all the effort that you put in - thanks for all the replies.
Patrick
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Old 05-08-2010, 09:32 AM   #7
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