Author Topic: Negative Active Power Reading  (Read 3345 times)

Rcroghan

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Negative Active Power Reading
« on: February 24, 2017, 05:13:50 PM »
I have  MTU3000 to one ECC (I hope I got that right).  So I installed the first MTU and connected it to the ECC and everything comes up fine readings are good.. I set the time and date. Reset the readings and history. Good to set up the second one.

I install the second MTU and when I review the ECC page.. its providing a negative dollar value yet everything shows a negative power (kW).   yet the kVa and V are positive and reading correctly.

The MTU 3000 Operational stats shows Active Power (W) as a negative.    I have tried moving where the PT's (voltage but it always shows negative.

Why would this be happening?  I've attached screenshots of the two MTU stats page and the ECC page. 

pfletch101

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Re: Negative Active Power Reading
« Reply #1 on: February 25, 2017, 01:14:32 PM »
How have you set up your system in System Settings|System Layout. It sounds as if the system thinks that your second MTU is monitoring Generation (e.g. from PV panels) rather than an additional Load.
Peter R. Fletcher
TED Pro Home - main MTUs monitoring utility and PV Solar feeds; 2 Spyders monitoring selected individual circuits

Support7

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Re: Negative Active Power Reading
« Reply #2 on: February 27, 2017, 10:36:38 AM »
As long as both your MTU's are set to load (Footprints > Settings > System Settings > System Layout) and your not measuring any type of generation then you should be getting positive values on both MTU's. Since MTU 2 is getting a negative value than that would lead me to believe that either the red dot on the CT clamps themselves are faced in the wrong direction or the CT clamps aren't on the correct phase as they are being powered from.

The red dots should all face the same direction and toward where the power is coming from. (typically away from the breaker and toward the utility)
If the red dots are facing the right way then you will need to swap the CT's until you get a positive value. You can do this while the MTU is powered on and looking at the stats page for the MTU. Unplug the CT's from the MTU 1 by 1 and swap them around. For example unplug CT from port A (closest to the power plug) and plug it into port C (farthest from power plug) and plug C into A and check for positive values. If still negative then swap A and B.

If you run into any questions or anything please let us know by going to http://www.theenergydetective.com/ticket and fill in the requested information to submit a support ticket so we can work to resolve any issues that may arise ASAP and make sure we provide the right firmware for any updates requested or required.
Have a wonderful day!

TED Support
www.theenergydetective.com

Rcroghan

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Re: Negative Active Power Reading
« Reply #3 on: February 28, 2017, 04:00:45 PM »
Yes rotating the CT's A-C,B-C. worked. Why is that?

Also in the system settings wizard, system layout, do I select "please select what each MTU is monitoring:" do I select stand alone or net.

I originally had them standalone or net?

The configuration I have is from one feed this goes to two panels - I am measuring A and B panels I'll live separate data. I do not understand what the difference between net or standalone

Support7

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Re: Negative Active Power Reading
« Reply #4 on: March 07, 2017, 09:36:20 AM »
Swapping the ports worked because with 3 phase loads using the MTU Pro you need to match up the CT with the correct phase that it is being powered from in order to get the polarity right. By default the MTU's are set to Net so they count toward your total. You would set it to stand alone if you do not want it to count toward the Net. For example if you were using 1 MTU to monitor the entire panel and then another MTU to monitor a circuit on that same panel then you would set it to stand alone to avoid getting that reading twice in your net total. You can view your MTU's separately on the Footprints page under System Overview with them both set to NET and then view the NET totals on the History Tab of the Footprints page. If you only want that NET to show one of your MTU's then set the other to Stand Alone.

Have a wonderful day!

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www.theenergydetective.com