How to digital read the presence(ON/OFF) of a 230V 50Hz AC current of at least xxmA?

Other Hardware Sensors
1

Hi,

there are analogue sensors to measure an 230V 50Hz AC current, such as the ACS712.

Suppose you just want to know if a device(laptop, router, etc.) is ON or OFF, suppose when it's on it's 45W, when in standby 30mA(6.9W), OFF of course 0W.

I wish to know, if there is a simple/easy digital sensor (or an easy diy one) to only indicate whether or not an AC device is actually powered, I presume(wrongly?) with some resistor(s) one can change the threshold of the detection, namely 10mA(2.3W), 30mA(6.9W), etc.

It seems to be doable with reed switch, but with a 50Hz I presume the internal metal blades will open/close at 50Hz rate and henceforth I presume the durability will be very limited.
(100'000 / 50hz = 20'000 ~ 6hours, I haven't found durability data on reed switch, but ball switch are in the range of 100K)

Sub question.
Are they digital current meters, just as there a digital temperature sensors(ds18b20), because I solely found analogue ones.
Use for at most 12A 230V AC, expected normal measure 30W to 300W with a precision of at worst 1% at measured current.

Thanks

P.S. Obviously, you can't use a relay to detect the actual ON/OFF,
as the relay would switch on/off the device but won't allow to stay in standby mode, (example laptop from hybernation to on, TV from standby to on, etc.)

2

You can use an analog sensor with a comparator IC circuit.

3

An opto coupler across back2back diodes can be used to detect low currents.
But that could be a (thermal) problem when it also could draw 12Amp.

Current sensors are always analogue, because current is analogue.

ACS712 (boards) are not rated for 230volt AC.
Current transformers are the way to go.
Leo..

4

https://miliohm.com/acs712-current-sensor-arduino/#:~:text=ACS712%20has%203%20types%20according,do%20you%20want%20to%20measure.

5

What does that mean.
If some internet poster is using it, then it's ok?
Leo..

6

Yes, and then you can take an ADC reading and do the threshold detection in software.

7

I find the sct013 Non-Invasive Current Sensors useful as you can just clip then onto a wire

8

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