Measure High Voltages:

[karan123]

how to measure high voltages

Hello,

I want to measure 220V AC signal with Microcontroller and Display on
LCD.

220V AC----->>Optocoupler----->>ADC---->> Microcontroller---->> LCD Display

Suggest me any Part No. for Optocoupler

I am using Optocoupler instead of Transformer for Stepping Down AC Voltage.

Is Above Configration will Work?

Please Send me Example Circuit.




KARAN

 

[cameo_2007]

ac voltage measurement using optocouplers

OH NO!!
or which is that optocoupler you are planning to use.may i know the part number.
To my knowledge there are no such optocoupler which can directly take 220VAC.
They normally comes in very low power applications.
please correct me if am wrong.

you need to reduce the voltage using transformer or resistor dividers to some values which can be processed by our low power electronic circuits.
getting the point??

 

[lats]

optocoupler measure high voltages

instead of optocoupler there should be step down isolator like transformer & then AC -dc convertor & then to ADC

 

[karan123]

measure high voltages

Dear cameo_2007

Thanks for Reply...

I have corrected my self.

220V AC ---> step down xmer --->rectifier --->ADC ----> microcontroller

Is it work.?

Can you send me example circuit??

 

[BABESH]

220ac measure

Hi Karan,

I am not good at hi voltages ckt but with my theoritical knowledge i can say that

Why xfarmer also,
just take 220AC, connect to bridge rectifier+filter Cap, you may get voltage of arround 310-320V DC accross Cap(Say100uF), and use a voltage divider using 500K and 10K which will drop the voltage in the range of 5V and you can use ADC to measure that.

Bridge rectifier and filter cap design is common you can implement from any text book ckt... it works..

Sorry if it too vague idea.


Tks.
Babesh.

 

[xvibe]

how do you measure high voltages using adc

if you remove the rectifier+filter and add some DC bias for the ADC you can also measure the frequency, peak, rms and mean.

 

[hakeen]

how to measure high voltage using adc

Hi Karan,

OH YES!! Optocouplers can be used for 220Vac measurement. there is no problem. There are optocouplers who can work till 1414Vpeak voltages. You just need dimensioned enough resistors to connect LED of optocoupler to mains. That is, voltage drop across LED will be in typical region (e.g. 1.5V) and current will be in mA. That is also good to lower power dissipation. Anotgher advantage is you need less space on PCB, rather than possibly bulky transformers do.

If you need very linear measurement, you can use also current/voltage sense optocoupler like HCPL-7510. With shunt, you can measure voltages. These parts are already used in Motor Phase measurements.

Regards
Hakeen

 

[levanhoc]

You can use Linear Optocouplers.
www.clare.com