If the fan stops working the high pressure switch (labeled S4 in your diagram)
should kill the power to the contactor coil, which will kill the power to the compressor.
Clogged condenser coils will do the same thing, i.e. cause a high pressure switch trip.
Ref:
Robert,
First I placed the Compressor CT around the Red and Yellow wires, and the Fan CT around the Purple and Orange wires. The results were both read around 1 amp when running - strange as I was expecting the compressor to read higher.
Next, I traced both line inputs from the Contactor and took readings on both inputs to the Contactor.
The readings on the Lines in fluctuated between 13.42 and 13.72 amps.
Next I placed the CTs over their respective black wires per the wiring diagram
and then took readings with my ammeter.
Compressor lead read 12.52
Under load, the emonPi2 read 12.42 for the compressor and 1.53 for the Fan. The fan consistently comes in higher than my ammeter readings.
However, under no load, emonPi2 still sees approx 1 amp on each of the compressor and fan CTs.
So, my original issue of not showing zero amps (or 0.5 as it shows on the unused CTs) still remains.
We were typing at the same time, and as your post is rather long, Iâm posting this to make sure you saw the comment I made while we were typingâŚ
Bill, good point and this would negate the need for a 2nd CT.
However, I still have the issue of not reading zero when the compressor isnât running. When I measure with my ammeter, it shows zero current, when the compressor stops, yet emonPi2 still shows approx. 1 amp.
I was contemplating subtracting 1 from the current reading before it goes into the feed, but then this understates the current draw when the compressor is running. I need an if statement but not sure if I can do this in emoncms. (something like, "if current is <2, then subtract 1, if not, leave as is).
thanks,
Gordon
Right. Just wanted to point out that you were âreinventing the wheelâ so to speak WRT
the function of your 2nd CT and the HP switch.
Iâm not sure as I stopped running emonCMS about 5 years ago.
But, if memory serves, you can do the math you mentioned.
@Robert.Wall is my memory flawed or�
Not flawed at all 
If >, skip next value: whatever
+ value: -1
Robert,
while the math approach is a potential stopgap, Iâd really like to figure out why I am getting the 1 amp readings. So, my next test is to setup a second emonPi2 with standard length CT cables to see if I get the same readings as this will help determine if it is a cabling related problem or something else.
Any other thoughts or suggestions of things to explore?
Thanks,
Gordon
Iâm reasonably certain, especially from what youâve written today, that the problem is pickup on the cables. But what itâs coming from and why isnât clear.
Obviously, measuring only the current in one winding wasnât anything to do with the non-zero reading, but it wasnât correct either.
You do mean it when you write â1 ampâ, because the emonPi doesnât normally read and display currents, only power or apparent power, even though the current is available to the sketch. How do you arrive at the âcurrentâ you are seeing in emonCMS?
I can only repeat that when I used a standard microphone cable of around twice the length you are using in a coil on a carpeted wooden floor, I was reading 1 W on a 240 V system â effectively zero current. When I laid the cable in a big loop with most of it on grass outside, I read about 16 W. Assuming youâre still not using a voltage reference, the difference of course is without a voltage reference, the rms maths is in effect rectifying any high frequencies picked up and reporting them as 60 Hz current.
I canât see where youâve told us the ratings of the c.tâs youâre using. What are they?
Iâll try to replicate your conditions (i.e. no voltage reference) and report what I find.
Robert, @TrystanLea created a unique build for me to expose measured current as I1, I2,âŚI6 so that I do not need to have an emonVS to provide reference voltage, power factors, etc. This is how I am able to see current directly.
For now, until I diagnose the cabling issue, my plan is to use the formula below for the compressor
For the fan, I am thinking of putting the CT on the line feed and subtracting the value from the compressor (or abandon the fan CT per @Bill.Thomsonâs suggestion).
I am using 100 amp CTs purchased from the OEM store.
It would, maybe not obviously, have been better to have chosen c.tâs more appropriate to the currents youâre measuring, because that way - assuming the unwanted signal is indeed being picked up on the cables and remains the same with the different c.t. - the wanted signal from the c.t. would be that much larger. E.g. even if youâd used 20 A c.tâs for both, youâd be reading 200 mA with no current instead of 1 A. Thatâs still 200 mA too much though.
I took apart the special lead I made up for your test, so Iâll need to remake it. If I then find I have similar results to yours, Iâll have something to work on. But as it is at present, and having done all the standard things and with no positive indication of what the source of the problem might be, Iâm struggling.
In a nutshell, the signal to noise ratio would be better. 
Is this using emonLibCM, not mains locked and running in âapparent powerâ mode? Because this is the first mention that itâs not using the default software, which would be emonLibDB as itâs
This is using emonLibDB, emonVs unplugged, and with 100 A, 50 A & 25 A c.tâs directly plugged in to inputs 1, 2 & 3 respectively:
16:32:34.714 -> Values will be reported every 9.80 seconds, using emonLibDB_V103e
16:32:44.799 -> Report 1, AC missing , Analogue reference calibration factor: 1.0050, Valid, V1 = 0.42 f = 79.56, Ch 1 I=0.063, Ch 2 I=0.029, Ch 3 I=0.013
16:32:54.650 -> Report 2, AC missing , Analogue reference calibration factor: 1.0032, Valid, V1 = 0.41 f = 76.64, Ch 1 I=0.064, Ch 2 I=0.029, Ch 3 I=0.013
16:33:04.472 -> Report 3, AC missing , Analogue reference calibration factor: 1.0017, Valid, V1 = 0.41 f = 77.20, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:33:14.293 -> Report 4, AC missing , Analogue reference calibration factor: 1.0022, Valid, V1 = 0.40 f = 77.20, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:33:24.080 -> Report 5, AC missing , Analogue reference calibration factor: 1.0035, Valid, V1 = 0.41 f = 74.85, Ch 1 I=0.063, Ch 2 I=0.029, Ch 3 I=0.013
16:33:33.931 -> Report 6, AC missing , Analogue reference calibration factor: 1.0040, Valid, V1 = 0.41 f = 77.58, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:33:43.747 -> Report 7, AC missing , Analogue reference calibration factor: 1.0038, Valid, V1 = 0.41 f = 81.26, Ch 1 I=0.063, Ch 2 I=0.029, Ch 3 I=0.013
16:33:53.595 -> Report 8, AC missing , Analogue reference calibration factor: 1.0034, Valid, V1 = 0.42 f = 80.25, Ch 1 I=0.064, Ch 2 I=0.028, Ch 3 I=0.013
16:34:03.411 -> Report 9, AC missing , Analogue reference calibration factor: 1.0013, Valid, V1 = 0.41 f = 78.15, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:34:13.261 -> Report 10, AC missing , Analogue reference calibration factor: 1.0037, Valid, V1 = 0.42 f = 81.51, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:34:23.078 -> Report 11, AC missing , Analogue reference calibration factor: 1.0043, Valid, V1 = 0.41 f = 79.54, Ch 1 I=0.064, Ch 2 I=0.028, Ch 3 I=0.013
16:34:32.892 -> Report 12, AC missing , Analogue reference calibration factor: 1.0052, Valid, V1 = 0.41 f = 78.39, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:34:42.740 -> Report 13, AC missing , Analogue reference calibration factor: 1.0066, Valid, V1 = 0.41 f = 75.50, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:34:52.562 -> Report 14, AC missing , Analogue reference calibration factor: 1.0064, Valid, V1 = 0.42 f = 80.53, Ch 1 I=0.064, Ch 2 I=0.027, Ch 3 I=0.013
16:35:02.374 -> Report 15, AC missing , Analogue reference calibration factor: 1.0073, Valid, V1 = 0.42 f = 80.05, Ch 1 I=0.063, Ch 2 I=0.029, Ch 3 I=0.013
16:35:12.189 -> Report 16, AC missing , Analogue reference calibration factor: 1.0056, Valid, V1 = 0.41 f = 72.12, Ch 1 I=0.064, Ch 2 I=0.028, Ch 3 I=0.013
16:35:22.041 -> Report 17, AC missing , Analogue reference calibration factor: 1.0070, Valid, V1 = 0.41 f = 74.93, Ch 1 I=0.064, Ch 2 I=0.028, Ch 3 I=0.013
16:35:31.856 -> Report 18, AC missing , Analogue reference calibration factor: 1.0068, Valid, V1 = 0.42 f = 82.24, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:35:41.674 -> Report 19, AC missing , Analogue reference calibration factor: 1.0056, Valid, V1 = 0.42 f = 78.27, Ch 1 I=0.065, Ch 2 I=0.028, Ch 3 I=0.013
16:35:51.559 -> Report 20, AC missing , Analogue reference calibration factor: 1.0048, Valid, V1 = 0.41 f = 75.32, Ch 1 I=0.065, Ch 2 I=0.028, Ch 3 I=0.013
16:36:01.408 -> Report 21, AC missing , Analogue reference calibration factor: 1.0019, Valid, V1 = 0.41 f = 75.90, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:36:11.222 -> Report 22, AC missing , Analogue reference calibration factor: 1.0024, Valid, V1 = 0.43 f = 82.39, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:36:20.972 -> Report 23, AC missing , Analogue reference calibration factor: 1.0024, Valid, V1 = 0.41 f = 72.64, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:36:30.890 -> Report 24, AC missing , Analogue reference calibration factor: 1.0025, Valid, V1 = 0.41 f = 77.78, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:36:40.705 -> Report 25, AC missing , Analogue reference calibration factor: 1.0041, Valid, V1 = 0.41 f = 79.94, Ch 1 I=0.063, Ch 2 I=0.028, Ch 3 I=0.013
16:36:50.518 -> Report 26, AC missing , Analogue reference calibration factor: 1.0027, Valid, V1 = 0.42 f = 84.67, Ch 1 I=0.063, Ch 2 I=0.029, Ch 3 I=0.013
Itâs counting 80 Hz cycles from somewhere - presumably ripple in the 5 V from my laptop via the USB lead.
With the emonVs providing power and a voltage reference, the ~ 63 mA from the 100 A c.t. falls to ~ 53 mA.
Robert,
Trystan has since made this a standard firmware version.
Iâm believe it is using emonLibCM. Iâm trying to check but Serial Config is not responding.
With the same long lead, I see about 4.4 A on the 100 A c.t. with the emonVs providing a mains earth in addition to the laptop earth, and about 1.65 A with the emonVs unplugged.
It looks as if this needs further investigation.
Hereâs the result of moving the long lead to the 100 A, 50 A & 25 A c.tâs in turn, then the 25 A and finally the 100 A with the emonVs unplugged.
17:00:37.126 -> Report 1, AC present , Analogue reference calibration factor: 1.0067, Valid, V1 = 233.34 f = 50.38, Ch 1 I=4.389, Ch 2 I=0.024, Ch 3 I=0.012
17:00:46.982 -> Report 2, AC present , Analogue reference calibration factor: 1.0055, Valid, V1 = 232.77 f = 50.26, Ch 1 I=4.354, Ch 2 I=0.024, Ch 3 I=0.012
17:00:56.802 -> Report 3, AC present , Analogue reference calibration factor: 1.0059, Valid, V1 = 234.51 f = 50.25, Ch 1 I=4.437, Ch 2 I=0.024, Ch 3 I=0.012
17:01:06.652 -> Report 4, AC present , Analogue reference calibration factor: 1.0043, Valid, V1 = 234.49 f = 50.24, Ch 1 I=4.404, Ch 2 I=0.024, Ch 3 I=0.012
17:01:16.472 -> Report 5, AC present , Analogue reference calibration factor: 1.0024, Valid, V1 = 234.10 f = 50.22, Ch 1 I=3.926, Ch 2 I=0.025, Ch 3 I=0.013
17:01:26.322 -> Report 6, AC present , Analogue reference calibration factor: 1.0047, Valid, V1 = 234.32 f = 50.21, Ch 1 I=0.226, Ch 2 I=0.026, Ch 3 I=0.013
17:01:36.139 -> Report 7, AC present , Analogue reference calibration factor: 1.0026, Valid, V1 = 233.67 f = 50.20, Ch 1 I=0.059, Ch 2 I=5.423, Ch 3 I=0.013
17:01:45.959 -> Report 8, AC present , Analogue reference calibration factor: 1.0029, Valid, V1 = 233.72 f = 50.17, Ch 1 I=0.063, Ch 2 I=2.170, Ch 3 I=0.012
17:01:55.776 -> Report 9, AC present , Analogue reference calibration factor: 1.0054, Valid, V1 = 234.47 f = 50.19, Ch 1 I=0.076, Ch 2 I=2.194, Ch 3 I=0.012
17:02:05.593 -> Report 10, AC present , Analogue reference calibration factor: 1.0055, Valid, V1 = 234.71 f = 50.17, Ch 1 I=0.053, Ch 2 I=2.201, Ch 3 I=0.012
17:02:15.442 -> Report 11, AC present , Analogue reference calibration factor: 1.0053, Valid, V1 = 234.80 f = 50.18, Ch 1 I=0.063, Ch 2 I=2.178, Ch 3 I=0.011
17:02:25.225 -> Report 12, AC present , Analogue reference calibration factor: 1.0074, Valid, V1 = 235.30 f = 50.16, Ch 1 I=0.051, Ch 2 I=2.232, Ch 3 I=0.012
17:02:35.111 -> Report 13, AC present , Analogue reference calibration factor: 1.0075, Valid, V1 = 235.26 f = 50.15, Ch 1 I=0.066, Ch 2 I=2.191, Ch 3 I=0.029
17:02:44.929 -> Report 14, AC present , Analogue reference calibration factor: 1.0073, Valid, V1 = 235.43 f = 50.14, Ch 1 I=0.055, Ch 2 I=2.301, Ch 3 I=0.012
17:02:54.779 -> Report 15, AC present , Analogue reference calibration factor: 1.0080, Valid, V1 = 235.09 f = 50.12, Ch 1 I=0.056, Ch 2 I=0.071, Ch 3 I=1.367
17:03:04.630 -> Report 16, AC present , Analogue reference calibration factor: 1.0077, Valid, V1 = 234.49 f = 50.11, Ch 1 I=0.049, Ch 2 I=0.028, Ch 3 I=1.087
17:03:14.450 -> Report 17, AC present , Analogue reference calibration factor: 1.0077, Valid, V1 = 234.71 f = 50.10, Ch 1 I=0.048, Ch 2 I=0.025, Ch 3 I=1.089
17:03:24.269 -> Report 18, AC present , Analogue reference calibration factor: 1.0070, Valid, V1 = 234.58 f = 50.12, Ch 1 I=0.049, Ch 2 I=0.032, Ch 3 I=1.094
17:03:34.052 -> Report 19, AC present , Analogue reference calibration factor: 1.0063, Valid, V1 = 234.42 f = 50.11, Ch 1 I=0.049, Ch 2 I=0.037, Ch 3 I=1.093
17:03:43.902 -> Report 20, AC present , Analogue reference calibration factor: 1.0068, Valid, V1 = 234.48 f = 50.12, Ch 1 I=0.049, Ch 2 I=0.028, Ch 3 I=1.085
17:04:30.804 -> Report 21, AC missing , Analogue reference calibration factor: 1.0070, Valid, V1 = 68.12 f = 5.27, Ch 1 I=0.052, Ch 2 I=0.029, Ch 3 I=0.506
17:04:43.246 -> Report 22, AC missing , Analogue reference calibration factor: 1.0064, Valid, V1 = 0.27 f = 1.20, Ch 1 I=0.051, Ch 2 I=0.027, Ch 3 I=0.414
17:04:53.462 -> Report 23, AC missing , Analogue reference calibration factor: 1.0081, Valid, V1 = 0.27 f = 1.08, Ch 1 I=0.052, Ch 2 I=0.026, Ch 3 I=0.414
17:05:04.173 -> Report 24, AC missing , Analogue reference calibration factor: 1.0077, Valid, V1 = 0.26 f = 1.12, Ch 1 I=0.052, Ch 2 I=0.027, Ch 3 I=0.409
17:05:15.119 -> Report 25, AC missing , Analogue reference calibration factor: 1.0045, Valid, V1 = 0.26 f = 0.37, Ch 1 I=0.052, Ch 2 I=0.026, Ch 3 I=0.412
17:05:26.596 -> Report 26, AC missing , Analogue reference calibration factor: 1.0031, Valid, V1 = 0.27 f = 0.87, Ch 1 I=0.052, Ch 2 I=0.026, Ch 3 I=0.414
17:05:36.579 -> Report 27, AC missing , Analogue reference calibration factor: 1.0022, Valid, V1 = 0.27 f = 1.20, Ch 1 I=0.052, Ch 2 I=0.026, Ch 3 I=0.419
17:05:47.760 -> Report 28, AC missing , Analogue reference calibration factor: 0.9996, Valid, V1 = 0.19 f = 0.82, Ch 1 I=0.056, Ch 2 I=0.028, Ch 3 I=0.691
17:05:57.876 -> Report 29, AC missing , Analogue reference calibration factor: 1.0023, Valid, V1 = 0.22 f = 3.55, Ch 1 I=0.191, Ch 2 I=0.029, Ch 3 I=0.291
17:06:25.045 -> Report 30, AC missing , Analogue reference calibration factor: 1.0047, Valid, V1 = 0.21 f = 2.67, Ch 1 I=8.542, Ch 2 I=0.028, Ch 3 I=0.013
17:06:36.057 -> Report 31, AC missing , Analogue reference calibration factor: 1.0047, Valid, V1 = 0.25 f = 0.55, Ch 1 I=1.671, Ch 2 I=0.026, Ch 3 I=0.012
17:06:48.199 -> Report 32, AC missing , Analogue reference calibration factor: 1.0047, Valid, V1 = 0.25 f = 0.33, Ch 1 I=1.681, Ch 2 I=0.026, Ch 3 I=0.012
17:06:59.410 -> Report 33, AC missing , Analogue reference calibration factor: 1.0041, Valid, V1 = 0.25 f = 0.18, Ch 1 I=1.681, Ch 2 I=0.026, Ch 3 I=0.012
17:07:12.479 -> Report 34, AC missing , Analogue reference calibration factor: 1.0042, Valid, V1 = 0.25 f = 0.38, Ch 1 I=1.690, Ch 2 I=0.026, Ch 3 I=0.012
17:07:23.225 -> Report 35, AC missing , Analogue reference calibration factor: 1.0038, Valid, V1 = 0.25 f = 0.56, Ch 1 I=1.674, Ch 2 I=0.026, Ch 3 I=0.012
17:07:33.771 -> Report 36, AC missing , Analogue reference calibration factor: 1.0063, Valid, V1 = 0.26 f = 0.48, Ch 1 I=1.706, Ch 2 I=0.027, Ch 3 I=0.012
17:07:44.618 -> Report 37, AC missing , Analogue reference calibration factor: 1.0060, Valid, V1 = 0.25 f = 0.74, Ch 1 I=1.668, Ch 2 I=0.027, Ch 3 I=0.012
17:07:55.330 -> Report 38, AC missing , Analogue reference calibration factor: 1.0057, Valid, V1 = 0.25 f = 0.37, Ch 1 I=1.627, Ch 2 I=0.026, Ch 3 I=0.012
17:08:05.278 -> Report 39, AC missing , Analogue reference calibration factor: 1.0078, Valid, V1 = 0.25 f = 0.50, Ch 1 I=1.647, Ch 2 I=0.027, Ch 3 I=0.012
I canât recollect this being published anywhere. It seems Iâm suffering a crystal ball failure.
Published here back in May 
emonTx4, emonPi2, emonTx5 14th May 2024 firmware release