Hello, I'm very new here. I would like to measure the current of three phases via current sensors. These should then be monitored by a microcontroller and if the current exceeds a limit, a relay should shut off the power supply. does anyone have an idea or even a script? Best regards dennis
What did you find when you Googled for "measure ac current arduino"?
Paul
hello Paul 
yes that's what I'm looking for but I still have to specify the current limits so that the arduino switches the relay. and I do not know that
Dennis1511:
hello Paul
Then identify what boards you are using and let us see what software you are using and what the results of your measurements are.
Paul
Ok thank you
Hopefully this is not going to be the primary form of protection for any device ? If it is then the Arduino is not suitable.
As this is a 3ph installation, your best bet is to purchase commercial curent transducers ( with 4-20mA output) , that can be wired in by a competent person , and the outputs used by yourself .
3phase power is a killer.
Dennis1511:
hello Paul
Unless you are dealing with instantaneous current, like motor in-rush starting current, use a clamp-on meter to view the current. Do for each phase.
Paul
Hello dennis,
i have using current sensor before on my micro-EDM machine, the sensor is ACS712.
Simple logic controller from my machine
24V psu > current sensor (ACS712) > Atmega 2560 > Stepper motor
Hope this can help
Access >> ACS712(1)
You have to know the current fromthe rating of your load and the phase voltage - you can then calculate the current . From that decide what range of currents you want to measure and the buy the appropriate number of current measuring devices ... if it’s a balanced load, you could use just one . If it’s unbalanced it gets more difficult