Measure AC Voltage and Current with optocoupler

ac optocoupler

Hello,
is it possible to measure ac voltage and current using the usual optocoupler like 4N35??

measure ac voltage

what is the idea that u have ?

linear optocoupler voltage measurement

What is the problem you have with this issue?
I think there are a a relation between the signal current (and/or voltage) on both sides of the opto, the specs should porvide that information. But then, of course you will have to implement a circuit to measure the parameter in the other side of the opto, like a ADC in a microcontroler.
Hope this can help or at least provide a pointing.

how to measure optocouplers

to optocoupler analog signal the better way is to convert voltage or current into digital and photocoupler digital signal using popular protocol (example...pwm or i2c) , you can resolve the problem by cheaper microcontroller (1-3 euro) with 4-8 analog channels

dc voltage measurement optocoupler

I dont know if there are available dual optocouplers. If so, you can linearize the optocoupler characteristic, by including one of the phototransistors is a negative feedback loop of an opamp. The second phototransistor will be used normaly, to pick the isolated signal.

proteus optocoupler

Actually this can be realize by the linear optocoupler like HCNR200. The linearity of the convensional opto is very low. So the linear opto like HCNR200 can be used in this case. The simulation model is available in proteus 7.1.

optocoupler linearization

change your volatge and current to frequency and then feed it to 4N35. Then measure the frequency back and calculate out back the volatge and current.

optocoupler voltage measurement

if you connect a microconroller with analog inputs for voltage and current and with mc drive with a string of bits in pwm mode a optocoupler , at the other side of photocoupler you can receive the pwm and reconvert all data into digital value without loss of precision.

main voltage sense optocoupler

As you know we can calculate the frequency of the signal using optocoulpler. So First step you have to do is conver voltage and current to frequency and the measure the data ......u will get result

optocoupler модель Протеус

Hi

You can use a simple phototransistor optocoupler for voltage sensing, but not so easily for voltage level measurement. With 4N35 you can set a threshold with a voltage divider connected to input. For level measurement I would kindly recommend some simple current sense optocoupler (like HCPL-7510). it is comparably cheap to other solutions and what you need is just a shunt resistor with few caps for Vdd pins. The analog output can be feeded to uC's A/D port. I made such a design for AC voltage sensing in DC motor control.

Hope it helps.

Best regards

PS. Another solution is also HCNR200. You need in this case a amplifier stage to multiply photodiode current in HCNR200. There are two exact Photodiode#s in package. I have no design with such a part, but seems interesting and realistic.

optocoupler measure voltage

Ex4,
forget that solution because optocoupler leds has degradation..
So led will lose its intensity with time(for two or three year %50 ) Search Google-> Optocoupler degradation
Regards

optocoupler characteristic

It is an interesting point. LED degradation is a fact, but my experience tells me it is misperceived by people (also partly due to marketing wars made by companies offering other technologies). I appreciate resources in internet, but some of them are biased by marketing purposes. My humble thoughts are:

Advantages of Optocouplers:
+ LED degradation is true, but light output never goes down to 50% of initial value after three years. For degradation data there are several sources, which are tested acc to standards (like MIL-STD-883). Some suppliers show some accelarated test data E.g. Page 11 of designer guide Agilent Technologies
+ Good CMR and EMI performance
+ ESD robust

Disadvantages:
- Comparably expensive technology (but simple photransistors are not)
- Many suppliers. The quality is not same for all. Use good ones e.g. TOSHIBA, AGILENT, SHARP

Personally I have a board (DC motor control, where high voltages -up to 600V- and harsh noise conditions are included) being 10 years old. It is still functioning without any problem.

PS. if you are still concerned, I recommend you to put a 40% margin on to your initial forward current.

Regards