CT 200 Accuracy and Calibration

[virtualfreak1]

I just noticed your values from the GEM's setup page is different from the other tool you used. One references 193 / 3 in the GEM's setup page.

Is channel 1 really been set to 193 /3 for the 200 amp CT? As the web page still shows the base values of 144/ 2 I expect?

As the other tool shows a value of 231 / 2 for the 200 amp CT?

Moving forward please only use the GEM's internal web setup page. The tool you showed earlier has been deprecated long ago.

So it did seem the voltage was low. I rebooted the GEM (the first time in a long time) and the voltage reading returned to normal. I also changed my settings to the New SEG Format. I'll compare the results after a few days.

[Teken]

I just noticed your values from the GEM's setup page is different from the other tool you used. One references 193 / 3 in the GEM's setup page.

Is channel 1 really been set to 193 /3 for the 200 amp CT? As the web page still shows the base values of 144/ 2 I expect?

As the other tool shows a value of 231 / 2 for the 200 amp CT?

Moving forward please only use the GEM's internal web setup page. The tool you showed earlier has been deprecated long ago.

So it did seem the voltage was low. I rebooted the GEM (the first time in a long time) and the voltage reading returned to normal. I also changed my settings to the New SEG Format. I'll compare the results after a few days.

How would you know the voltage is fine with out measuring the line voltage at the PT outlet with a DMM?

[virtualfreak1]

I just noticed your values from the GEM's setup page is different from the other tool you used. One references 193 / 3 in the GEM's setup page.

Is channel 1 really been set to 193 /3 for the 200 amp CT? As the web page still shows the base values of 144/ 2 I expect?

As the other tool shows a value of 231 / 2 for the 200 amp CT?

Moving forward please only use the GEM's internal web setup page. The tool you showed earlier has been deprecated long ago.

So it did seem the voltage was low. I rebooted the GEM (the first time in a long time) and the voltage reading returned to normal. I also changed my settings to the New SEG Format. I'll compare the results after a few days.

How would you know the voltage is fine with out measuring the line voltage at the PT outlet with a DMM?

Sorry, I left of the statement that I checked the line voltage at the PT outlet with a DMM and it was around 117v which was higher than what the GEM was reporting at that time which was 93v. So I unplugged the GEM and plugged everything back in and GEM Internal webpage showed a voltage reading around 118v. My utility company has a website that posts my daily usage but it lags by 3 days so I have to wait a few days to compare my readings with theirs. I do have one days comparison since I rebooted and there is still a 12kWh to 16kWh difference. Here are my numbers for June 16

There is a 4kWh discrepancy on my solar production. I produced (Solar):
23kWh of Total Solar Power according to my inverter data
19kWh of Total Solar Power according to my GEM data sent to SEG (uses two CT-40s)

my utility shows I used 56kWh for the day of grid energy (Grid)
my GEM shows I used 63.6kWh Total Energy for the day (Grid + Solar)

So if my GEM reading were accurate then (GEM Solar - GEM Total Energy = Grid Energy Used)

My GEM readings still seems to be low.

[Teken]

Well the first problem I see is the reliance on SEG. You have no method to confirm all data is present and accounted for as historically the service has been down for maintenance or simply down.

Next what is your send interval to SEG? Anything below 45 seconds will cause errors per Sam at SEG.

Next how does your POCO read your meter and does it end exactly at midnight each month? The DB stops accumulating energy data each month at midnight.

If your system was very old like mine and one of the first in production. I would monitor the PT voltage and insure the voltage remains the same. If you see a drift it could be a sign of a bad PT Transformer I had a Cusco unit that went bad.

Regardless you didn't answer my question about the difference in the 200 CT values?

Your screen shot indicates two different settings being used. Go into the GEM web page and set the 200 CT's again for each channel you have.

You also want to make sure none of the CT are canceling one another due to incorrect wiring.

There are some test you can do to also fine tune the CT but complete the above and report back.

You should also be monitoring the voltage at SEG. This will allow you to track any drift and without guessing.

Also, please confirm your GEM is using the latest COM / Engine firmware.


Ideals are peaceful - History is violent

[ben]

You may consider setting up BTMon.py with SEG on a local PC and running that in unison with your SEG setup to see if there's any differences you can spot.

[virtualfreak1]

Well the first problem I see is the reliance on SEG. You have no method to confirm all data is present and accounted for as historically the service has been down for maintenance or simply down.

Next what is your send interval to SEG? Anything below 45 seconds will cause errors per Sam at SEG.

Next how does your POCO read your meter and does it end exactly at midnight each month? The DB stops accumulating energy data each month at midnight.

If your system was very old like mine and one of the first in production. I would monitor the PT voltage and insure the voltage remains the same. If you see a drift it could be a sign of a bad PT Transformer I had a Cusco unit that went bad.

Regardless you didn't answer my question about the difference in the 200 CT values?

Your screen shot indicates two different settings being used. Go into the GEM web page and set the 200 CT's again for each channel you have.

You also want to make sure none of the CT are canceling one another due to incorrect wiring.

There are some test you can do to also fine tune the CT but complete the above and report back.

You should also be monitoring the voltage at SEG. This will allow you to track any drift and without guessing.

Also, please confirm your GEM is using the latest COM / Engine firmware.


Ideals are peaceful - History is violent

- SEG send interval is 45sec (see screenshot).
- my POCO reads the meter daily (see screenshot). It appears to be midnight to midnight
- Thanks for the voltage tip! I added voltage as a stream to SEG for monitoring
- I'm using the GEM internal website exclusively for setup now. I re-applied the CT-200 config to the appropriate channels. (See screenshot)
- I checked and the 4 channels capturing total Energy consumed are all positive values (See Screenshot)
- I'm on 3.24 COM and 1.49 ENG
- I'll be adding pictures of my system to https://smartenergygroups.com/virtualfreak

I will continue to monitor and compare over the next several days. Thank you for all the above suggestions.

[Teken]

You will need to verify ALL CT's are properly connected and orientated correctly per the users manual. You should also do a load test to verify the CT values have been properly accepted by the GEM.

I know way back in the day the tool you showed early on would allow over writes to the GEM and these values would not show up in the GEMs internal web page. Take a few moments to reapply the CT values for all 32 channels.

This will eliminate this area of concern . . .

One thing to note is to have a reference base to reflect upon. I did this simple test in one of my threads where I used 60, 100, 1500, 1800 watt resistive loads. This will tell you if there is any large variances in the circuits you're monitoring.

I found that I had three CT's out of spec and fined tuned them for better accuracy. I also found one of them were completely out of band and the system had the wrong values entered.

[virtualfreak1]

My gem voltage is consistantly 8v lower than measured by a power meter. What is the process or adjusting the gem voltage?

[Teken]

My gem voltage is consistantly 8v lower than measured by a power meter. What is the process or adjusting the gem voltage?

The first question I have is, is the digital multi-meter (DMM) a true RMS unit? If so measure the outlet where the PT is plugged into.

Before you start make sure the meter has fresh batteries and the probes are clean.

Then insert the probes all the way and measure both hot to neutral. Then hot to ground and both values should be the same.

Write down the measured line voltage at the PT outlet on a piece of paper. Login to the GEM's internal set up web page. Under the tab channels at the top will be the PT type and range. You will change the *Type* one numerical value at a time and select save.

Select the refresh button to show what the GEM believes the line voltage is. Keep adjusting the type until it matches the value on the piece of paper you wrote down. Once done log out of the GEM's set up page and close the browser.