How do you measure voltage and current main network 220 volt

[Kamel.alhomsi]

Hello..
How do you measure voltage and current main network 220 volt 20 amp using Micro Atmega
thank you

 

[kamalkannan12]

Voltage can be measured after step down and rectified as 5V DC. But I thought It was not a stable method.
And current sensors available in market..

 

[KlausST]

Hi,



If you don´t need a galvanic isolation:
Voltage: a resisitve voltage divider with AC coupling and bias to ADC_range/2 is simple hardware, but you need good sampling technique to calculate true RMS.

Current: Shunt with OPAMP, also bias to ADC_range/2.

****

I recommend to use true RMS. It gives the most reliable voltage/current reading in an AC system.

Only if you know the waveform (pure sine) and you know the behavior of the load (for example: absolutely resistive), then you can use more simple methods.

More simple methods could be: rectifying and averaging, or peak voltage measurement.

********


Klaus

 

[oilbay54]

The circuit in this diagram will help you to measure the voltage of the mains.
R1=R2=1 MOhm R3=39 KOhm, R5=3.3 KOhm, R4=10 KOhm C1= 10uF tantalum. All the resistors except R4 should be 1% metal film.
The reverse voltages of the diodes in the bridge rectifier should be 600V minimum, such as 1n4006 or 1N4007. The linearity of the output is fairly good in the voltage range 40 to 264 Volts.
IMPORTANT NOTE: Since lethal voltage is introduced to the circuit please be extremely careful not to touch any part of the circuit with bare hand or with any conductor.

Another way is to use a small transformer 220 - 11V and 1VA. In this case the bridge rectifier does not work as the forward voltage drops of the diodes introduce 1.4 V, thus for small voltages there may be no output at all. Also the transformer itself introduces very high nonlinearity.
To overcome the first problem an ideal rectifier (with two OP/AMPS) should be used. To overcome the second problem (nonlinearity) assume that the voltage output of the transformer is linear in a small window such as 0 -20, 20.1 to 40, 40.1 to 50 etc, and put a multipoint calibration program in yourcontroller

 

[bilal malik]

I don't know about atmega but link given below have each and every thing you need to know to measure AC voltage and current
for AC voltage measurement https://microcontrollerslab.com/ac-voltage-measurement-using-microcontroller/
For AC current measuremnt : https://microcontrollerslab.com/alternating-current-measurement-using-pic-micocontroller/
I hope this helps you

 

[Kamel.alhomsi]

I want to measure battery voltage from 6 to 16 volts and therefore put a voltage divider 5 volts
Vin=r2/(r1+r2)Vout
so 6 to 16 volts battery
0 to 5 volt micro
0 to 1023 ADC
i want to connecting between them

- - - Updated - - -

I want to measure battery voltage from 6 to 16 volts and therefore put a voltage divider 5 volts
Vin=r2/(r1+r2)Vout
so 6 to 16 volts battery
0 to 5 volt micro
0 to 1023 ADC
how can connecting between them ??

 

[KlausST]

Hi,

"main network 220V" made me think of AC....


*****

Now DC:
0..16V: you need a voltage divider 16V --> 5V
(please don´t use the unstable 5V as reference voltage for your ADC, this gives too much error. Use a external 4.096 or 3.00V Ref instead)

If you need 16V you should add some overhaed. So let´s say 20V.
Use a resistive divider of about 30k and 10k for 5V input
or 57k and 10k for a 3V input. you could lower both resistors down 5k7 and 1k0.

Add a (at least) 10nF ceramic capacitor in parallel to the lower resistor. Place it near the ADC input.

With the 20V input range you get a voltage resolution of about 20mV.

Klaus