3 phase power convert to 3.3v raspberry pi signal

Question

I have a project about to mantain a data log of a 3 phase motor, when the more is on and off count that time and save in memory location.

I don't use any server now to save data, I use a Rpi to do all this stuff. Any other controller I can use suggest please.

I want that 3 phase signal on my Rpi when the switch is on, 1- 3 phase AC to 3.3v dc signal? Thank you.

Answer 1

Use a relay.

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. A possible circuit.

The relay separates your 3-phase from your 3.3 V Raspberry Pi circuit making it a safe system.