Electical Loads on Line 1 and Line 2, Allegro RED

[bigb56]

Originally Posted by wog099

I am still on 30 amp shore power and did the following tests this morning on the MW receptacle and others (all receptacles measured the same volts). This was checking the receptacles with a multimeter and checking the amp usage with the PI EMS.
1) 125 volts and 0 amps - Nothing being used
2) 119 volts and 12 amps - Front Heat Pump being used
3) 115 volts and 23 amps - Front Heat Pump and electric heater being used.
These were the amps shown on the EMS and the volts measured in several receptacles, including the MW receptacle (all receptacles measured the same).
With nothing but the MW on using 30 amp shore power, it uses 16 amps according to the EMS.
Does this data tell anyone anything?
Thanks,

My test today may shine some light on your readings. Again I connected a line splitter at the MW and clamped on my Amprobe but this time I recorded the readings from the EMS display as well. Before starting the MW the PI 30 amp hard wired EMS display showed 1 amp and 124 volts. (The 1 amp was my converter). I then started the MW and the Amprobe again went to just under 13 amps (@121 volts) which is right in line with the specs, however the EMS display showed 16 amps. My math says 13+1=14 so I think the discrepancy you are seeing is in the EMS which may not be 100% accurate. I recall there is some type of adjustment that can be made on the HW units but I don't recall if it was volts or amps but I kind of recall it was volts.
At any rate the only way to know for sure is to check at the MW plug with a real Amprobe or similar tool, mine is a professional Amprobe brand that I used in my career as an electrician. I think that the EMS amp reading is slightly inaccurate but close enough for our needs.

[JohnCZ]

Originally Posted by bigb56

My test today may shine some light on your readings. Again I connected a line splitter at the MW and clamped on my Amprobe but this time I recorded the readings from the EMS display as well. Before starting the MW the PI 30 amp hard wired EMS display showed 1 amp and 124 volts. (The 1 amp was my converter). I then started the MW and the Amprobe again went to just under 13 amps (@121 volts) which is right in line with the specs, however the EMS display showed 16 amps. My math says 13+1=14 so I think the discrepancy you are seeing is in the EMS which may not be 100% accurate. I recall there is some type of adjustment that can be made on the HW units but I don't recall if it was volts or amps but I kind of recall it was volts.
At any rate the only way to know for sure is to check at the MW plug with a real Amprobe or similar tool, mine is a professional Amprobe brand that I used in my career as an electrician. I think that the EMS amp reading is slightly inaccurate but close enough for our needs.

Thanks Brian. That just may be it. I may have to invest in a clamp-on ammeter. Before I do that, I see that my Magnum Remote Control panel will display the AC voltage and current outputs in either pass through mode or inverter mode. So, I can compare the current at the inverter output with that of the PI EMS with only the Microwave and Inverter powered.
Maybe that will be telling. Maybe that will validate any error in the PI EMS, even though they claim an accuracy of +/- 1 amp.

[bigb56]

Originally Posted by JohnCZ

Thanks Brian. That just may be it. I may have to invest in a clamp-on ammeter. Before I do that, I see that my Magnum Remote Control panel will display the AC voltage and current outputs in either pass through mode or inverter mode. So, I can compare the current at the inverter output with that of the PI EMS with only the Microwave and Inverter powered.
Maybe that will be telling. Maybe that will validate any error in the PI EMS, even though they claim an accuracy of +/- 1 amp.

John, I am second guessing myself on the 16 amps, it might have been 15. I wanted to take pics but holding the Amprobe to where I could see it, turning on the MW and fumbling with the phone was too much. I am positive the Amprobe showed 13 but second guessing the EMS, I'll check again. It's pretty easy for me as my MH is right out in the garage.

[96 Wideglide]

I use a portable PI EMS, and the amp draw is always a little lower on it, compared to the Magnum panel.

Makes sense since the power still has to travel a 40' 50A cord, cord reel contacts, ATS, breaker panel, junction box.

[bigb56]

So I checked again and took pics this time. First I turned off the converter. The EMS said 123V 0A. I started the microwave, EMS=121V 16A. Amprobe at MW says 12.5A. Next I switched on the converter, EMS still said 123V 0A! I started the MW, EMS said 121V 16A. I turned off the MW and EMS still said 0A with converter on! Then I switched EMS to "bypass" and back, now it read 123V 1A! Switched MW back on and it again read 121V 16A. At no time did the Amprobe show more than 12.5 amps, and the EMS read 16 amps with the MW running while the converter was off and the same while the converter was on. In light of this I am assuming that the EMS display is not 100% accurate and errors on the high side. It may also have something to do with the microwave function fooling the EMS circuitry which is above my pay grade. This might also explain how we have gotten away with running when the display said 32 amps on occasion although I wouldn't expect the breaker to trip right away at 31 or 32 amps anyway. I seriously doubt my Amprobe is inaccurate as the 12.5 reading is exactly in line with the 1,500 input watts at 120 volts. ie 120X12.5=1,500

Maybe tomorrow I'll pull the deadfront off my panel and clamp onto the 30 amp circuit conductor with the Amprobe.

[bigb56]

I did find another thread on here from 2018 where someone was having the same issue https://www.irv2.com/forums/f54/accu...er-414375.html

[JohnCZ]

Originally Posted by bigb56

I did find another thread on here from 2018 where someone was having the same issue https://www.irv2.com/forums/f54/accu...er-414375.html

Brian, this link to the other thread and your other info is helpful. Thanks.

The other thread was exactly the issue Wade and I are seeing. One thing I saw from one commenter in the other thread, every time the MW was involved in his testing, the EMS read high compared to a clamp on ammeter. I am beginning to think that under certain circumstances, there is just something odd about the MW and EMS combination. It will be interesting when I test this again and see what my Magnum Inverter Remote Control panel is showing as AC Output voltage and current when running the MW on pass through, and how these readings compare to the PI EMS. The only difference "should" be related to any resistance in the wiring from the EMS into the coach, throught the Surge Guard surge protector and auto transfer switch, to the Main breaker, then from the Inverter Output breaker to the inverter and through the inverter pass through switch. You would think this path of proper guage wiring and a couple components would not create much resistance load.
Plus, all the other loads besides the MW seem to be in line with what is expected. I'll soon see.

[bigb56]

Being as the issue seems to be related the microwave ovens I did a little research and found that a microwave oven is a non-linear load which means it affects the waveform on the line making it non-sinusoidal. To get a true current reading from a non-sinusoidal waveform a True RMS meter must be used as opposed to just an RMS meter. My old meter is RMS, but not True RMS.
See the following explanation:
https://www.fluke-direct.com/pdfs/re...ue-rms-usd.pdf

and video

https://www.youtube.com/watch?v=-VfqwBXt3mQ

In the past I briefly studied non-linear loads and their effect on building wiring and utility supply as fluorescent lighting and computers are non-linear. At that time we were using oversized neutrals in some cases due to harmonics caused by these non-linear loads which can overheat shared neutrals in large commercial settings. I will also say that these non-linear loads are not favored by utility suppliers and the extra current measured by the True RMS method is wasted current, it is not doing any of the work at the load but must still be provided for in equipment sizing and delivery capability.

So while the labeling on the microwave says 1,500 watts max that is the max it can use to provide the output power of 1,200 watts but it does not count the non-linear waveform it is imposing on the incoming line which is seen as additional current by everything upstream of the load.

The PI unit must therefore be True RMS however I cannot locate more in depth specs on their units, have you found any? Hope this makes sense.

[bigb56]

Another video, the testing starts at about 2:30

https://www.youtube.com/watch?v=RFhG7l1YmBI

[bigb56]

Linear vs Non Linear

[High Road Travelers]

Brian, this is fascinating and way above my level of knowledge. I understand some of it now though (after reading and watching your videos), and greatly appreciate your efforts and willingness to work on this issue with us.
If I understand this correctly it seems that the Progressive Industries EMS HW50C that John and I have is actually measuring amperage usage as a "True RMS". That is why the amp readings seem to be high on the MW but showing what we would expect on other equipment. Is this understanding/assumption correct, that we are seeing the true rms reading on the EMS? (I looked in my EMS manual and it does not explain how it is measuring amps).
We seem to be OK actually using 16 amps or so as the MW is on a dedicated 20 amp circuit, but a standard rms meter would only show 12 amps or so; is that correct?
Please confirm or correct my understanding if you will.
Thanks very much,

[bigb56]

Originally Posted by wog099

Brian, this is fascinating and way above my level of knowledge. I understand some of it now though (after reading and watching your videos), and greatly appreciate your efforts and willingness to work on this issue with us.
If I understand this correctly it seems that the Progressive Industries EMS HW50C that John and I have is actually measuring amperage usage as a "True RMS". That is why the amp readings seem to be high on the MW but showing what we would expect on other equipment. Is this understanding/assumption correct, that we are seeing the true rms reading on the EMS? (I looked in my EMS manual and it does not explain how it is measuring amps).
We seem to be OK actually using 16 amps or so as the MW is on a dedicated 20 amp circuit, but a standard rms meter would only show 12 amps or so; is that correct?
Please confirm or correct my understanding if you will.
Thanks very much,

Yes your thinking is correct. I too learned something out of this and I am always open to learning and I am surprised that the PI tech support was not up to speed on this in the case of the other thread, although not that surprised.

[JohnCZ]

Originally Posted by bigb56

Yes your thinking is correct. I too learned something out of this and I am always open to learning and I am surprised that the PI tech support was not up to speed on this in the case of the other thread, although not that surprised.

Wow! Brian, thanks so much. This HAS to be the answer.
Wade and I and others have eliminated everything else. I have actually exchanged a couple emails with a gentleman in PI's tech support. He never brought this up. But, I will verify with him that their EMS is True RMS, or not.

That might also explain why the wattage measured (VDC and Amps) with my Magnum Remote Control panel while running the MW on the inverter correctly aligns with the MW nameplate, when adjusting for the 10% loss at 90% efficiency. DC voltage not impacted by Root Mean Square, as it is not sinusoidal to begin with.

Agree?

[bigb56]

Originally Posted by JohnCZ

Wow! Brian, thanks so much. This HAS to be the answer.
Wade and I and others have eliminated everything else. I have actually exchanged a couple emails with a gentleman in PI's tech support. He never brought this up. But, I will verify with him that their EMS is True RMS, or not.

That might also explain why the wattage measured (VDC and Amps) with my Magnum Remote Control panel while running the MW on the inverter correctly aligns with the MW nameplate, when adjusting for the 10% loss at 90% efficiency. DC voltage not impacted by Root Mean Square, as it is not sinusoidal to begin with.

Agree?

Sounds plausible, but then I am no EE, just a blue collar here. Maybe a qualified EE will stumble on this thread someday and confirm our findings.