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CR800 and current transformer readings


Benjamin.vial Dec 16, 2022 03:19 PM

Hello,

here the program created via shortcut to read AC current transformers.

I was trying to have measure but have for now just NAN value, and just see something that I think it could be the problem. Just look at the program (created with shortcut), it seem that "amperage" is filled with "CS11Array(4)" which, if I'm not wrong, contain 4 values, but one is recorded ; is there not a msitake here ?

Could it be the NAN ?

 

 

'CR800 Series
'Created by Short Cut (4.4)

'Declare Variables and Units
Dim CS11Array(7)
Public BattV
Public PTemp_C
Public Amperage

Units BattV=Volts
Units PTemp_C=Deg C
Units Amperage=A

'Define Data Tables
DataTable(Table1,True,-1)
	DataInterval(0,1,Min,10)
	Sample(1,Amperage,FP2)
	Average(1,Amperage,FP2,False)
EndTable

'Define Data Tables
DataTable(Table2,True,-1)
	DataInterval(0,10,Min,10)
	Minimum(1,BattV,FP2,False,False)
EndTable

'Main Program
BeginProg
	'Main Scan
	Scan(5,Sec,1,0)
		'Default CR800 Datalogger Battery Voltage measurement 'BattV'
		Battery(BattV)
		'Default CR800 Datalogger Wiring Panel Temperature measurement 'PTemp_C'
		PanelTemp(PTemp_C,_50Hz)
		'CS11 Current Transformer measurement '5'
		ACPower(CS11Array(),1,50,1,1,6.6,2,0.2,50,1)
		Amperage=CS11Array(4)
		'Call Data Tables and Store Data
		CallTable Table2
	NextScan
EndProg

 


JDavis Dec 19, 2022 05:44 PM

The ACPower instruction returns several values. The fourth value is the amperage. Program code looks correct to me.

Check your sensor wiring.


Benjamin.vial Dec 20, 2022 09:06 AM

Of course, you're right, "CS11Array(4)" donesn't mean four values but the fourth value, my bad.

Sensor is not the CS11 (CR8459) sensor but a similar model CR8448, same model but different scale of measure (see manufacturer doc here).

It just have 2 wires (black / white) and a shield. Shortcut tells me to plug white on a SE channel and the black on the GND. I tried the reverse side in the case the manufacturer changed his color code during years, but same results NaN.

Reading sensor directly with a voltmeter give me, in DC, something about 40 mVdc and, in AC, something about 7 Vac.

Is the ACPower instruction reads AC or DC voltage ? Since you have to enter a frequencie in the instruction, maybe it's AC voltage ? But I'm not sure.


JDavis Dec 20, 2022 11:42 PM

You need to put a burden resistor between the two wires to change the output from microamps to millivolts. The resistance R shown on the manufacturer document is not inside the transducer. You have to add it. Pick a resistor value that will create a peak voltage less than the 5 volt max of the CR800.

A CS11 has a burden resistor in the cable wiring.


Benjamin.vial Dec 21, 2022 01:01 PM

Thanks for your instruction, I understand much better the situation. Here is my (new) installation :

Plugged the CR8448 with a resistor of 6,5 kohm in parallel between 1H and Mass, which with the DCR of 134 ohm of the transducer, make a voltage divider bridge of (134*(134+6800)) = 0,019. 

So, in theory, for a reading voltage of 6,7 Vac ont the transducer, I should have something about 0,13 Vac on the CR800, that correspond to approx. 0,25 A of current on the electrique circuit I'm measuring.

I modified the program to read the first four value (power, frequency, voltage and amperage). And here we go !

When the electric circuit is off, here the measures :

Power : NAN

Freq : NAN

Volt : 0,9

Amp : 0,38

When the electric circuit is on (and consomes approx 0,25A), the measures is :

Power : NAN

Freq : 50,02

Volt : NAN

Amp : 0,34

In conclusion, only frequency seem to works correctly. I'm in france, so it's 50 Hz electrical network.


Benjamin.vial Dec 21, 2022 03:35 PM

Ok I tried harder, and here my new instruction ACPower :

ACPower (CS11Array(),1,50,1,0.345,245,2,0.045,10,1)

This time, I'm using 2 transducers, the first on SE1 (1H) dedicated to voltage measure and the second, on SE2 (1L) for current. In both case, second wire is connected to Mass.

I succeeded to read 240 volts on a first installation to measure, and it droped on 140 volt on a second installation... But both are connected to public electrical network.

Current is incorrect, even if value are near to zero when electricity is off.

Only frequency still clearly read correctly.

I'm beaten by this problematic ...


Benjamin.vial Dec 22, 2022 01:52 PM

Hi again, problem seem to escape to me, I tried things, but things goes wrong.

1. Here a schematics with my installation, to understand much better and much faster.

https://drive.google.com/file/d/1kt9ecXYC8y3xdnRgLHiBaNeh7kx9cMWg/view?usp=share_link

2. And here my actual program :

 

'CR800 Series
'Created by Short Cut (4.4)

'Declare Variables and Units
Dim CS11Array(7)
Public BattV
Public PTemp_C
Public Power
Public Freq
Public Voltage
Public Amperage
Public ac5
Public ac6
Public ac7
Public bat

Units BattV=Volts
Units PTemp_C=Deg C
Units Power=W
Units Freq=Hz
Units Voltage=V
Units Amperage=A
Units ac5=mV
Units ac6=mV
Units ac7=mV
Units bat=mV

'Define Data Tables
DataTable(elec,True,-1)
	DataInterval(0,1,Min,10)
	Sample(1,Power,IEEE4)
	Average(1,Power,IEEE4,False)
	Sample(1,Freq,IEEE4)
	Average(1,Freq,IEEE4,False)
	Sample(1,Voltage,IEEE4)
	Average(1,Voltage,IEEE4,False)
	Sample(1,Amperage,IEEE4)
	Average(1,Amperage,IEEE4,False)
	Average(1,bat,IEEE4,False)
	Sample(1,bat,IEEE4)
EndTable

'Define Data Tables
DataTable(soh,True,-1)
	DataInterval(0,10,Min,10)
	Minimum(1,BattV,FP2,False,False)
EndTable

'Main Program
BeginProg
	'Main Scan
	Scan(10,Sec,2,0)
		'Default CR800 Datalogger Battery Voltage measurement 'BattV'
		Battery(BattV)
		'Default CR800 Datalogger Wiring Panel Temperature measurement 'PTemp_C'
		PanelTemp(PTemp_C,_50Hz)
		'CS11 Current Transformer measurement '5'
		ACPower (CS11Array,1,50,1,0.345345,240,2,0.045045,15,1)
		Power=CS11Array(1)
		Freq=CS11Array(2)
		Voltage=CS11Array(3)
		Amperage=CS11Array(4)
		ac5=CS11Array(5)
		ac6=CS11Array(6)
		ac7=CS11Array(7)
		'Generic Differential Voltage measurements 'bat'
		VoltDiff(bat,1,mV5000,2,True,0,_50Hz,1,0)
		'Call Data Tables and Store Data
		CallTable elec
 		CallTable soh
	NextScan
	SlowSequence
	  'synchronize on the GPRSrouter
	  Scan (10,Min,3,0)
	  NetworkTimeProtocol ("192.168.1.1",0,1000)
  EndSequence
  NextScan
EndProg

3.  Then a sample of my readings :

"TOA5","27231","CR800","27231","CR800.Std.32.05","CPU:20221221_RMStest.CR8","27858","elec"
"TIMESTAMP","RECORD","Power","Power_Avg","Freq","Freq_Avg","Voltage","Voltage_Avg","Amperage","Amperage_Avg","bat_Avg","bat"
"TS","RN","W","W","Hz","Hz","V","V","A","A","mV","mV"
"","","Smp","Avg","Smp","Avg","Smp","Avg","Smp","Avg","Avg","Smp"
"2022-12-22 10:54:00",0,"NAN","NAN","NAN","NAN",94.15902,93.09134,23.96245,23.95538,"NAN","NAN"
"2022-12-22 10:55:00",1,"NAN","NAN","NAN","NAN",0.05639315,77.61749,0,17.34002,"NAN",3975.142
"2022-12-22 10:56:00",2,"NAN","NAN","NAN","NAN",101.9476,59.86477,24.86521,12.96576,"NAN","NAN"

[...](when 230Vac is on)

"2022-12-22 12:39:00",105,"NAN","NAN","NAN","NAN",96.37223,96.25818,12.47387,12.52448,-1.530094,-1.700105
"2022-12-22 12:40:00",106,"NAN","NAN","NAN","NAN",96.09265,96.20923,12.93446,12.68134,-1.473423,-1.020062
"2022-12-22 12:41:00",107,"NAN","NAN","NAN","NAN",92.80463,95.85542,12.78806,12.62486,-1.700103,-1.360083

[...]

"2022-12-22 13:38:00",164,"NAN","NAN","NAN","NAN",0.0638093,0.05362438,0,0,-1.416808,-1.70016
"2022-12-22 13:39:00",165,"NAN","NAN","NAN","NAN",0.06380954,0.06095904,0,0,-1.416794,-1.700149
"2022-12-22 13:40:00",166,"NAN","NAN","NAN","NAN",0.06380989,0.05688083,0,0,-1.473469,-1.70019

4. Then finally some measures in a graph :

https://drive.google.com/file/d/1ueg3A841YBDj3FBT7BANyDLG2B72jkT6/view?usp=share_link

Frequency is no longer read (or rarely). Voltage & Current are incorrect, even if it drop to zero when I cut off the 230Vac (several time in a day). And I put a VoltDiff instruction to read battery tension (with a ratio of 3.5, so 3.4 Vdc read is 12Vdc "true") and even this measure is totally wrong, and random.

And so, I don't understand.


JDavis Dec 22, 2022 08:53 PM

Please confirm if you are using the CR8448-1000 ot the CR8448-2000. Different sub models would be different multipliers.

A NAN analog measurement will happen if the signal is higher voltage than the input range. Maximum input range on the CR800 is +-5VDC. Smaller ranges as seen in the VoltDiff instruction are available. Voltage on an analog channel compared to Earth(on the datalogger) should not exceed 5V either.

The ACPower() instruction selects an input range based on the MultI and MaxIrms values used. Your latest program is using default values used for transducers with 0.333Vac output. The multiplier is in units of Amps/millivolt

For CR8448-2000 with 6.7 kOhm burden resistor:

V= (1 amp * 6700)/2046 = 3.275 Volts at 1 amp of current

2 amps would overvoltage the channel. I believe you are using too high a resistance value for the burden resistor. It limits the amount of current that can be sensed.

 


Benjamin.vial Jan 5, 2023 10:32 AM

Hello JDavis,

thanks for your answer,

My transducer is CR8448-2500-N.

In order to follow your indication, and want to measure until 10 amps, I change my burden R on the CR800 to use 620 ohm. With your calculation, I must have something about 2470 mV ; I would passthe CR800 on 2500 mV scale but I just realize that with ACPower instruction, you can't choose the input scale.

I just looked in dev config utility and measures still 'NaN' with new burden R.

And measuring manually the CR8448 in open circuit give me approx 30 mV, for 0,12 A measured with an ammeter on the 230 Vac.


Benjamin.vial Jan 13, 2023 09:47 AM

Hello,

I've used an oscilloscope to read transducer with certitude.

So with a measured current of 90 mA stable (with two different models of clamp ammeter), a transducer CR8448-2500-N produce a potential of 20 mV peak-to-peak at 50Hz.

But reading the CS11 manual, there are several resistances, including the burden resistance, that could be a part of my problem ; I think I have to reproduce a CS11 and adapt the resistance value, to obtain a good measure. Could you please indicate me what the resistance value on the diagram (page 6 of the manual) :

resistance diagram


Benjamin.vial Jan 23, 2023 12:46 PM

Hello,

I'm still in need of information about the resistance of the CS11 if someone got them, because I'm stuck in this problem that I currently can't solve, in spite of my efforts.

Bye


Benjamin.vial Feb 14, 2023 07:27 AM

Hello,

I refresh the topic, anyone have an idea on this technical informations about resistances in the CS11 component ?

And, if someone know how to choose an input voltage with the ACPower instruction, I'm interested. I don't know the default value and it not seem to be writen in the manual (but I could miss it).

Then I could try to reproduce a CS11 with my CR8448 (that the same serie of component).


Benjamin.vial Feb 23, 2023 01:05 PM

Hello,

I'm refreshing, still stuck actually.

Bye


Icicibankexpert Mar 2, 2023 04:18 AM

Hello,

I've used an oscilloscope to read transducer with certitude.

So with a measured current of 90 mA stable (with two different models of clamp ammeter), a transducer CR8448-2500-N produce a potential of 20 mV peak-to-peak at 50Hz.

But reading the CS11 manual, there are several resistances, including the burden resistance, that could be a part of my problem ; I think I have to reproduce a CS11 and adapt the resistance value, to obtain a good measure. Could you please indicate me what the resistance value on the diagram (page 6 of the manual) :

resistance diagram geometry dash unblocked

have same problem. You soved it?


johnnygregory Mar 7, 2023 04:31 AM

This post is under review.


Benjamin.vial Mar 9, 2023 01:48 PM

have same problem. You soved it?

Nope. Do you using the "original" CS11, or like me another model from the same serie ?


Allone Mar 10, 2023 05:09 AM
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