MTU Configuration Clarifications

[Support7]

Stand Alone Net - Reads bi-directional values, reports Raw MTU value (whether + or -). History displays the cumulative values recorded, and this is NOT applied to the NET reading.

Load - All values are seen as positive regardless of direction. The values are recorded,totaled and added to NET.

Generation - Load multiplied by -1 and added to NET.

Adjusted Load - This is the calculated value of the raw MTU reading and Generation values. The displayed information is the combined value added to the NET.

Example: Your house is using 4Kw, you are generating 5Kw. You have two MTUs, MTU1 is set to Adjusted Load, and MTU2 is set to generation. MTU1 measures a value of -1Kw (raw value), but displays 4kW and the raw value is added to NET. MTU2 measures -5Kw, displays -5kW. Your NET displayed reading would be -1Kw. To get the actual Load of your house in this setup, you would need to add the absolute value of the Generation to the raw Adjusted Load value.

NOTE:As long as a Generation value is being added, An MTU set to Adjusted Load will always display a positive number. Otherwise the MTU will display the same values as Stand Alone Net.

Stand Alone - Identical to Load but the value is not added to the NET.

[willingp]

I have TWO solar installations, but only one MTU.  Where can I find setup instructions so that my single MTU reads NET use or production?
--in other words, it should be positive when I'm using from the grid, and negative when I'm sending to the grid

It looks like my newer installation is set up on a circuit breaker in the main panel and the old one taps into the cables just before the breaker panel.   Do I need to put my transformers in front of (grid side)  that tap into the breaker panel?

Thanks.

[willingp]

MONITORING NET USE/PRODUCTION OF SYSTEM THAT INCLUDES TWO PV SYSTEMS:

"Clarifications" didn't clarify, but by trial-and-error, I now seem to have this correct in setup.  Perhaps these instructions should be included somewhere?  My Setup:

--Are you generating solar?  YES
--Solar configuration?  ADJUSTED LOAD
--Transformers:  red dot FACING PANEL.  When I had them facing away, my solar production was adding to use, not subtracting; now it gives a negative number when I'm sending to grid, and positive when I'm taking from grid.

[RussellH]

--Transformers:  red dot FACING PANEL.  When I had them facing away, my solar production was adding to use, not subtracting; now it gives a negative number when I'm sending to grid, and positive when I'm taking from grid.

Transformers: Trial and error.  Not only does the direction of the dots make a difference, but also which clamp goes on which wire.  However, you should make sure both dots face the same way or else you will get errors.

[willingp]

Yes; thanks!
 I switched transformers to the opposite wire, and it would only give me negative readings for BOTH solar input and for use (e.g., at night).

[rotomike]

I have a question, I have 2 MTU's the first one is monitoring a subpanel at the main leads and the second is monitoring a single breaker in the same panel.   Everything works good.   I have first one set to load and second to stand alone.   is there a configuration that would take the load on the second one and deduct it from the total load shown from the first one.  Basically I want to know what everything is using in the subpanel except that one breaker so trying to figure a way to deduct that breaker from the load. 

Mike

[Support7]

Thanks for your question Rotomike,

Try setting your MTU1 to Adjusted load and the MTU2 to load, and see if that gives you what you are looking for.


Best Regards,

TED Forum Support

[rotomike]

That did not work it added 1 and 2 together. 

Mike

[Support7]

Rotomine,

You could also set the MTU you want deducted and set it to Generation (even though it is not) and it will take the measured value, multiply it by -1 and add it to the other MTU value.

Regards,

TED Forum Support

[det2500]

I read through the posts and am not totally clear on the correct MTU connections and what to call each one in footprints.

I have a solar panel system with two arrays feeding two breakers into the bottom of my electrical panel. I have one MTU pair on the wires from the meter to the bus bars. The second MTU pair is on the solar wires before the breakers. I have each MTU over both wires from each array. That is to say both black wires go through one MTU clamp and both red wires through the other. I have the red dots on all clamps facing the source of power.  My MTU’s are #1 adjusted load, #2 generation.

I am getting a total of usage and generation when I read MTU #1, this is difficult to understand.
 
What I would like is if I click on net I read my current power status positive or negative where and how much KW, if I am adding to the grid or taking away. When I click on MTU 1, I want to see how much I am currently using to power my house. When I click on MTU 2 I want to see how much my solar is producing.

Is there a way to achieve this?

[det2500]

I didn’t get any help here but that’s OK. What really surprised me is I have had a help ticket in for 4 days with only an automated response. TED, you have a great product, are you out of business? If you help the people that own it more people will hear how good it is and buy!

Well anyway the reason I am posting is I found out a few things that may help others.
First I found my meter clamps from the main line coming in MTU 1 were backwards, The red dot was facing the panel, I changed them to red dot facing source and now MTU1 reads positive, in fact all readings make sense.

My next move was to give the gateway its own dedicated line that nothing else would use, except in a rare instance. I had a line going to an outside outlet that I wired back through the wall inside, hooked up the gateway and now my MTU 1 reads backwards, again. I am using just the black wire and had to move it to the other phase to use this new circuit. For a test I moved it back to the other first phase and now readings are positive.

I don’t recall reading about this in any help sections. In short, if you are using the black / white only for the MTU moving it from one side of your panel bus bar to the other will change direction of the readings when the MTU is set for adjusted load.

[pfletch101]

Well anyway the reason I am posting is I found out a few things that may help others.
First I found my meter clamps from the main line coming in MTU 1 were backwards, The red dot was facing the panel, I changed them to red dot facing source and now MTU1 reads positive, in fact all readings make sense.

The instructions could make it clearer that, in practice, pairs of MTUs that are configured in Footprints to read current direction as well as magnitude need to be oriented with the dots on each one facing in the same direction, but whether this direction should be towards or away from the panel for the sign of the reading to be correct needs to be determined by experimentation.

I don’t recall reading about this in any help sections. In short, if you are using the black / white only for the MTU moving it from one side of your panel bus bar to the other will change direction of the readings when the MTU is set for adjusted load.

The MTU/Gateway determines the direction of current flow by comparing the phase of the current (from the MTU) and voltage (from the black wire) readings. Since, on a normal domestic 240V system, the voltage waveform on one bus bar is 180 degrees out of phase with that on the other, switching the power connection to the MTU to the other side of the bus (!) will, indeed, reverse the reported direction of current flow.

[RussellH]

The MTU/Gateway determines the direction of current flow by comparing the phase of the current (from the MTU) and voltage (from the black wire) readings. Since, on a normal domestic 240V system, the voltage waveform on one bus bar is 180 degrees out of phase with that on the other, switching the power connection to the MTU to the other side of the bus (!) will, indeed, reverse the reported direction of current flow.

Likewise switching the CT clamps (dots toward/away) or swapping the CT clamps between the two wires.

[Insaneoctane]

This thread is timely for me....
I just added my MTU2 for my solar array today.  With just 1 MTU, things were working great, but now that I've switched MTU1 from LOAD to ADJUSTED LOAD, it's now showing negative.  Damn.  I read that's because it was probably always negative, but the MTU setting of LOAD always forces values to positive, so I never knew.  Now that I need it to be at ADJUSTED LOAD, I'm realizing that I must have the CT clamps "wrong".

So, RussellH, your previous post tells me I can EITHER swap MTU1 CT clamps to opposite wires OR keep them on the same wires, but switch the direction of the dots, correct?  If so, I'll leave the directions of the dots (pointing at the energy supply source) and just switch the two CTs to opposite wires.  I would much appreciate confirmation on this.  Next, once my PUC gives me my PTO, I'll finally see if I've got my MTU2 CTs in the correct order....but, I have to wait for that....

[pfletch101]

So, RussellH, your previous post tells me I can EITHER swap MTU1 CT clamps to opposite wires OR keep them on the same wires, but switch the direction of the dots, correct?  If so, I'll leave the directions of the dots (pointing at the energy supply source) and just switch the two CTs to opposite wires.  I would much appreciate confirmation on this.  Next, once my PUC gives me my PTO, I'll finally see if I've got my MTU2 CTs in the correct order....but, I have to wait for that....

Your reading of the posts is correct.