2nd and 3rd VT not working

Homebrew IoTaWatt
1

Hi Bob,

I am playing with the 2nd and 3rd VT’s and having some trouble. Please check me here:-
1.We load them under channel 13 & 14 respectively ( with 1st VT being on channel 0 )
2.We dont need R10 and R11 in place , and
3.We should not be using CT’s in 13 & 14.
4.Additionally, we remove burden input on 13 & 14 ( software )

If so , i am not getting any voltage reading on 2 , nor 3 - when i click to calibrate it wants to default to 120 and immediately goes to zero. I have done a physical check on the actual VT’s with a multi and they are outputting voltage. VT1 is also doing something funny in that it doesnt settle down ( racing up and down then again ).

AM i missing something ?
ps. i don’t have 3phase derived ticked

2

Hi Bob - not sure if you missed this post or not? Some further input

  1. My production unit is working perfectly with VT 2 & 3
  2. My dev unit is not working on 2 & 3 ( i am getting 120V volts flash ever so quickly on start of pressing the calibrate button and then it stays at 0 ) regardless of what i set calibration value to.
  3. I did find the post where Promy had a similar question and i did update eeprom to Version 5.0 thinking that would help - but still didn’t.
    What else could i be missing please?
3

You are building your own hardware and it isn’t working. The reason I’m not getting involved is that you don’t appear to understand how this works, and are not doing (or at least mentioning) the obvious troubleshooting that goes part and parcel with tinkering.

Please don’t take offense. I realize you are trying to learn something here, but I just don’t have the time to get involved at this level. I suggested you reach out to other homebrew folks, and you did, but they do not appear interested either.

Here’s where I’ll leave it. You should be seeing the same voltage at the ADC pins for channels 13 and 14 that you see on the channel 0 pin. If you do, it’s a software problem. If not, it’s a hardware problem. The circuit on each input is pretty simple. You can figure it out by looking at the schematic, using a voltmeter, and ohms law.

4

Bob - although narcissistic, i appreciate your response. You are right - its my issue and i truly get that - i thought a few pointers here and there would not hurt you or your modus operandi…

I guess open source doesnt mean open help at the end of the day. The truth is that the forum is so small i cannot really call on many people that have any interest in helping. I will keep on prodding along as best i can. Tx

5

It’s like in “the Firm” where the FBI guy asks Mitch if the bills are all he has, and Mitch replies “Did you look at this stuff?”

I just told you how to figure this out and you call me narcissistic. Nice.

6

It’s perhaps just the condescending attitude Bob. I do find your comments narccisictic. But again , thanks for your help. I will try what you have pointed out.