Reading AC voltage and Current using voltage divider circuit

[gravi]

Hi,

I have seen in sinewave invertors, Voltage and Current are read with voltage divider circuit connected to an ADC of a micro controller. Can any one tell me, What is the sequence I need to follow to read Volatge and Current of main supply with out using external Energy Metering IC.

Thanking You,
Ravi Kumar.

 

[rajudp]

for voltage you can use resister divider with rectifier make sure the voltage to the micro controller is not over the maxim limit( 3.3v, 5v etc), you can use a zener diode to protect the port,
for current use a current transformer with rectifier

 

[gravi]

Hi raju,

Can you tell me what are the steps to be followed during programming.

 

[rajudp]

for simpe calculation
read volt
read current
calculate power volt*current

for good design
you have to consider pf also

 

[gravi]

Dear Rajudp,

My question is how to read AC voltages and Current using an ADC, I hope it is not similar to read DC voltages using an ADC of an microcontroller.

I am looking for Flow diagram or process involved in reading.

 

[rajudp]

ok,
you have to read adc values for a specified count and average it

you can add capacitors after rectification 100uf will give almost stable result but it will increase the response time
capacitor of 1uf is ok will do for this types of application ( that much faster response is not needed)

 

[aq_mishu]

if i use a cap after step down and rectification, then how can I get the RMS voltage?