AC voltage and calibration

[nickdd]

Hi,

I just received my M16-v2.1 board and will use it with 10A and 20A 0-1V clamps. New to the forum :-)

I'm on a 3x400V+N network and connected L1, L2, L3 and N to the terminals to measure the voltage.
But the voltages that are reported seem to be too low.


I also have a Zennio Kes Plus KNX device that also measures voltage and power consumption. (top 3 values in image below).
I also tried 2 different multimeters and get nearly the same readings as the Zennio (and I measured on the inputs of the M16)

But the M16 readings are 8-12 volts lower.



Is there a way to calibrate the voltages?
I'm using home assistant with ESPhome

If not: can I use the voltages from another home assistant entity (my Zennio) and use these?

After that I would like to start calibration of the CT-clamps: is it advised to do individual clamp calibration for each connection?

Regards,
Nick

[nickdd]

About the calibration:
I use SCT013-010  (10A 0-1V) clamp.
When I check the logs for some known loads (100W light bulb, 500W light and hair dryer) I got these values from the logs:

0.41A:  (100W bulb):
[22:28:14][D][sensor:094]: 'ai1': Sending state 1.01400 V with 3 decimals of accuracy
[22:29:14][D][sensor:094]: 'ai1': Sending state 1.01900 V with 3 decimals of accuracy
[22:30:14][D][sensor:094]: 'ai1': Sending state 1.01000 V with 3 decimals of accuracy

1.79A (500W halogen bulb):
[22:36:14][D][sensor:094]: 'ai1': Sending state 1.09700 V with 3 decimals of accuracy

6.56A (1500W hair dryer)
[22:23:14][D][sensor:094]: 'ai1': Sending state 1.24500 V with 3 decimals of accuracy

If I look at the datasheet the values should be between 0v (0A) and 1v (10A)
http://en.yhdc.com/comp/file/download.do?id=943

=> why do I always get values above 1V to start with?  
Or would that be an issue with the clamp?  They are supposed to be original SCT013's.
Picture:



Any help or advise is welcome!

Thanks,
Nick

[admin]

we will test, feedback later.

[admin]

1. run arduino calibration program code to find your "Sensitivity" value for ESPHome M16v2 component. 
here is arduino code: https://www.kincony.com/forum/showthread.php?tid=3089
before use this arduino code, you need install "ZMPT101B" arduino library firstly.
then before run this code, use multi meter test your L and N voltage , then only "Change this based on actual voltage" in code:
   
   
when running this code, serial port will print  "Sensitivity" value at the end.
   
then change  "Sensitivity" value in home assistant "/homeassistant/esphome/zmpt101b/zmpt101b_custom_sensor.h"
   
now it's completed.

[nickdd]

Hi,

Thanks for the info. I ran the procedure for all three phases and slightly adjusted the custom sensor code:
I have different sensitivity values for each sensor and that's why I ended up with this:

#define SENSITIVITY_L1 523.0f
#define SENSITIVITY_L2 513.0f
#define SENSITIVITY_L3 530.25f

    if(this->adcPin==34) {
      this->zmpt101b->setSensitivity(SENSITIVITY_L1);
    }
    if(this->adcPin==36){
      this->zmpt101b->setSensitivity(SENSITIVITY_L2);
    }
    if(this->adcPin==39){
      this->zmpt101b->setSensitivity(SENSITIVITY_L3);
    }


Voltages now kind of match my voltmeter's measurement.



Any tips for the calibration of the CT clamps?
I don't get the values I get from them as they are all over 1V  (see above).  As a result the number of amperes is therefore too high in my readings.

Regards,
Nick

[admin]

two types of sensr you can chose:
output: 0-50mA or 0-1v dc
if your amperes is therefore too high, because you need to calibration in esphome.

sensor:
- platform: ct_clamp
sensor: adc_sensor
name: "Measured Current"
update_interval: 60s
filters:
- calibrate_linear:
# Measured value of 0 maps to 0A
- 0 -> 0
# Known load: 4.0A
# Value shown in logs: 0.1333A
- 0.1333 -> 4.0


- 0 -> 0
- 0.1333 -> 4.0
these two command line data need replace by yourself. you can use multi meter to test a AC220v load's current, then see the RAW data in esphome log.

[nickdd]

Hi,

Yes, but I am using SCT013-10 and SCT-013-20 (10A and 20A) 1V versions.
But why do I see voltages higher than 1 volt in the raw output?

100W bulb: [sensor:094]: 'ai1': Sending state 1.01000 V with 3 decimals of accuracy
1500W heater:[sensor:094]: 'ai1': Sending state 1.24500 V with 3 decimals of accuracy

=> so even for low wattage I have raw values of > 1V
But according to specs of SCT013 I believe it should be within 0V and 1V range?

So I understand the calibrate_linear but not why I have raw values that seem too high?

[admin]

RAW just a value of ADC, it's not actually value, it's not important.
so every CT sensor need calibration.

[nickdd]

I did some more testing:
- only connected 1 single CT to first port (ai1)
- tested with a stable load of 3.33 amps (a halogene lamp of 750W)
- set the update interval to 5 seconds in esphome 

from the logs I filter out the raw values and they are very jumpy:

Line  113: [23:55:28][D][sensor:094]: 'ai1': Sending state 1.16500 V with 3 decimals of accuracy
Line  147: [23:55:33][D][sensor:094]: 'ai1': Sending state 1.03000 V with 3 decimals of accuracy
Line  176: [23:55:38][D][sensor:094]: 'ai1': Sending state 1.15000 V with 3 decimals of accuracy
Line  205: [23:55:43][D][sensor:094]: 'ai1': Sending state 1.18100 V with 3 decimals of accuracy
Line  234: [23:55:48][D][sensor:094]: 'ai1': Sending state 1.18700 V with 3 decimals of accuracy
Line  266: [23:55:53][D][sensor:094]: 'ai1': Sending state 1.18400 V with 3 decimals of accuracy
Line  295: [23:55:58][D][sensor:094]: 'ai1': Sending state 1.16700 V with 3 decimals of accuracy
Line  324: [23:56:03][D][sensor:094]: 'ai1': Sending state 1.09100 V with 3 decimals of accuracy
Line  353: [23:56:08][D][sensor:094]: 'ai1': Sending state 1.07500 V with 3 decimals of accuracy
Line  382: [23:56:13][D][sensor:094]: 'ai1': Sending state 1.06500 V with 3 decimals of accuracy
Line  411: [23:56:18][D][sensor:094]: 'ai1': Sending state 1.06200 V with 3 decimals of accuracy
Line  440: [23:56:23][D][sensor:094]: 'ai1': Sending state 1.06400 V with 3 decimals of accuracy
Line  469: [23:56:28][D][sensor:094]: 'ai1': Sending state 1.05200 V with 3 decimals of accuracy
Line  498: [23:56:33][D][sensor:094]: 'ai1': Sending state 1.06400 V with 3 decimals of accuracy
Line  527: [23:56:38][D][sensor:094]: 'ai1': Sending state 1.00400 V with 3 decimals of accuracy
Line  556: [23:56:43][D][sensor:094]: 'ai1': Sending state 0.93600 V with 3 decimals of accuracy
Line  585: [23:56:48][D][sensor:094]: 'ai1': Sending state 0.88700 V with 3 decimals of accuracy
Line  618: [23:56:53][D][sensor:094]: 'ai1': Sending state 0.90700 V with 3 decimals of accuracy
Line  647: [23:56:58][D][sensor:094]: 'ai1': Sending state 0.95100 V with 3 decimals of accuracy
Line  676: [23:57:03][D][sensor:094]: 'ai1': Sending state 1.09000 V with 3 decimals of accuracy
Line  705: [23:57:08][D][sensor:094]: 'ai1': Sending state 1.17200 V with 3 decimals of accuracy
Line  734: [23:57:13][D][sensor:094]: 'ai1': Sending state 1.18100 V with 3 decimals of accuracy
Line  763: [23:57:18][D][sensor:094]: 'ai1': Sending state 1.06300 V with 3 decimals of accuracy
Line  792: [23:57:23][D][sensor:094]: 'ai1': Sending state 0.95900 V with 3 decimals of accuracy
Line  821: [23:57:28][D][sensor:094]: 'ai1': Sending state 0.88600 V with 3 decimals of accuracy
Line  850: [23:57:33][D][sensor:094]: 'ai1': Sending state 0.94900 V with 3 decimals of accuracy
Line  879: [23:57:38][D][sensor:094]: 'ai1': Sending state 1.07400 V with 3 decimals of accuracy


Tested with some other clamps (10A - 1V) but am getting the same result.

No idea what I can do next but haven't been able to get a proper reading yet.

Regards,
Nick

---

RAW just a value of ADC, it's not actually value, it's not important.
so every CT sensor need calibration.

I am attempting the calibration but have such a big spread in these raw values: ranging from 0.88 to 1.19V of raw value of ADC state for a stable load.
Or is that interval of 5 seconds too low like this?

[admin]

it's normal. because it's AC load, The load is not constant, and the power grid is changing, the CT sensor's signal also is AC signal.