EKM Not tracking Utility Smart meter

[Nevland]

No mater how I try to compute it, I can not seem to match the EKM's readings with my utility's (PG&E) smart meter.

What does "Total KWH" really mean ?
I now see a line in Dash, I have not seen before "Forward KWH".
This seems to mean Total KWH - Rev Total KWH

What readings do your clients who do sub metering use to get net KWH used?
Total KWH
EKM Utility
9/30/2012 13527.0 22813
10/6/2012 13789.0 22925
10/11/2012 14020.9 23078
10/12/2012 14058.1 23097
10/13/2012 14113.8 23125
10/14/2012 14165.5 23152
10/15/2012 14206.8 23173
10/15-9/30 679.8 360

Interesting is: The Total wattage between EKM and the "Smartmeter" is consistent.
Within a few watts of each other.
Total Rev KWH has not changed in months. Was originally running due to incorrect
original install instructions. This should not be factor.

Whats going on here ???

Bill

[Jameson]

Hello Bill,

What does "Total KWH" really mean ?

Total kWh is Forward kWh + Reverse kWh. If you have a system that has power flowing in one direction (from the gird to the house or load in most cases) then you should not be seeing Reverse kWh incrementing if the meter is connected properly. If this is the case then you can use Total kWh (which will equal Reverse kWh if there is no Reverse kWh).

Yes Forward kWh = Total kWh - Reverse kWh

Reverse kWh is really only for measuring power that is flowing back to the grid in the case of power generation. This could be solar or wind, etc.

To better comment on the discrepancy you are seeing I would have to know more about the data on the EKM meter. Do your voltage, amperage, and power factor readings make sense on both lines? Are the EKM meter values from the column on the right? Is this for a 120/240 volt single phase system or a 3-phase system?

Regards,

[Nevland]

Originally hooked my meter per printed furnished instructions. Reverse was incrementing.
Video at the same time showed as different hook up.
Anyway about three month ago decided to fix it per latest instructions. The reverse reading has not changed in the last three months.

Total Kilowatt Hour 14270.2
Voltage1 122.9
Current1 (amps1) 7.6
Power1 (watts1) 824
Cosθ 1 (Power Factor1) 1.00

Above was taken from dash readings Computer Date 2012-10-16 23:58:38
This should equate to 934 watts (122.9 X 7.6 X 1.0=934) not 834
I pointed out some time ago that V*A*pf did not compute.
Note Dash does not allow a more than 1 line to be copied to the clip board art a time.
Dash locked up after a few minutes (does this often). Does not release the comport without a computer reset.

Since the Revere reading has not changed Net KWH should equal Total KHW -Previous
Total KWH. Table I send shows meter readings taken at the same time.
EKM shows I am using almost twice as much as PG&E & says. PG&E readings are consistent with readings from a year ago (old Meter)

I am really bumed out over this

It all started by PG&E offering a Time of use" rate.
I thought I could use the EKM to figure if this would be a better deal for me.
I can't make any sense out of the time of time of use figures or how the sub meters are supposed to bill the net amount used.

How does the EKM firmware actually measure KWH ?
Was my meter Ct ratio set for the CT's that were sent to me?

Bill

[Jameson]

Bill,

I am still not seeing enough information (I assume you are on a 120/240 volt system with 2 hot lines). The very best would be to email us the .csv file from your meter reads. To do this you go to EKM Dash> File> Export. Create the csv, this will show us voltage on all line, amps on all, lines, and power factor on all lines, as we as how your kWh is incrementing. I should be able to make a much better judgement of what could be going on.

Which version of the Dash are you running? We are up to v.360. If there are stability issues, we would very much like to hear about them so that we can fix them. Please let us know your exact operating system and exactly what happened leading up to any stability issues.

You should be able to use your EKM Meter to track different Time-of-Use periods. Go to Dash > Help > Send Diagnostic Information, send this, it will include your meter database, I can then take a look at it and see how you have your Time-of-Use settings set.

EKM Metering's hardware utilizes a very powerful metering chip. Our meters take voltage samples from each line and current samples from each line over 25,000 times per second. I dont know your meter model, but we have meters that are between 0.5% accurate and 1% accurate, this exceeds the standards of most Utility Meters. And of course if there is really an issue, we will fix it.

You can see the CT ratio you have your meter set to in the EKM Dash data, this will show up in the .csv file also. What amperage of CTs do you have installed?

Regards,

[Nevland]

What really bugs me is that the instant wattage in use does track.

Requested cvs file sent.

Bill

[Nevland]

Possible Clues
Cts hooked up per original printed instructions that came with meter Wht Blk Wht Blk
Rev Total Hours were incrementing.
Old notes seems to indicate that EKM might have been tracking Ok at that time
Problem maybe caused by trying to correct this Reverse incrementing by hooking up
CT's per new instruction posted on website Blk Wht Blk Wht
Rev KWH did not increment after change.
Forward TKWH seems to be now incrementing at twice (*2) Smart Meter
EKM PG&E EKM PG&E PG&E
10/6/2012 13789 22925 Net Net *2
10/11/2012 14020.9 23078 37.2 19 38
10/12/2012 14058.1 23097 55.7 28 56
10/13/2012 14113.8 23125 51.7 27 54
10/14/2012 14165.5 23152 41.3 21 42
10/15/2012 14206.8 23173 89.2 47 94

Note: EKM installed down stream of woodshed that has florescent night lite and battery
Maintainer load. PG&E should lead EKM by small amount.

Bill

[Jameson]

Hello Bill,

Thanks for sending us your .csv file (very helpful). From looking at it we do not see any issues. You have a 120/240 volt system, you are registering volts and amps on each line. You have the Omnimeter set to be used with 200 amp CTs (let us know if this is not the CT rating that you have connected to your meter). I see that you are getting double the expected PGE value so this would be the first thing to look at.

Just a heads up, from looking at the .csv, it looks like you have some bad power factor from time to time, on line 2.

We would never go off of the amps x volts x power factor = watts. I do not think this number is ever going to be truly correct. The meter measures each of these values down to a few decimal places and is sampling 25,000 times per second. The amps, volts and power factor that you see returned are rounded approximations. The kWh however is what we certify and what we stand behind. If you were to determine that your Omnimeter is not 0.5% accurate for some reason we would replace it.

The CT wires should be hooked up to the Omnimeter from left to right Black, White, Black, White, like you say. You are correct that your Reverse kWh is no longer incrementing (indicates CTs are properly connected).

Regards,

[Nevland]

I went out and double checked my CT's.
They are marked 200a 26.9ma, so CT ratio seems to be set correctly.

The puzzlement here is that the watts in use, do match.

Seems to me we are left with
1. An error in the firmware (not likely but possible) But if this were the case you should have more than one with this same problem. It would be hard to believe that nobody else had checked it's accuracy regarding net KWHs.

2. A miss set jumper or switch on the circuit board. (my best guess but I have never seen the ckt bd. Don't know if it has jumpers or switches.
3. A defective meter. Yes but the rest of it seems to be working Ok

4. The PG&E meter is wrong. Very Very unlikely. Lots of attention given to them on
the change over.

The balls in your court, what do we do next ??

Bill

[Jameson]

Hi Bill,

We would be happy to take a look at your meter for you.

You can ship it to our address:
EKM Metering Inc
363 Berkeley Way
Santa Cruz, CA
95062

Please include a note with the package (important) explaining the issue you are seeing so we can better test it.

We will put it on our test bench and run for a while. Thanks for helping us understand the issue you are seeing.

Sorry for this trouble, again we will stand behind it and make it right.

Best regards,

[Nevland]

Questions
What would be the results if:
One of the arrow labels was installed incorrectly.
Mine are both pointing to the load.

Have you ever seen this particular problem before ?

We are getting the first storm of the season. This is the time I will need the EKM to monitor the generator's output.

I will send it in for you the examine but first I would like to exhaust all the possibilities of a local error.

Bill