How to detect when a 3-phase motor is running?

I try to come back with Arduino programming.

I have a 3 phase motor 220v, running in our farm. It’s used to pump water.

I would like to add simple system which would track when motor has started to run and when stopped.

But how to detect it? I have tried with non-invasive SCT-013 device but I think I don’t have enough skills and maybe could not get it working because 3 phases. I don’t want to open motor and do any things inside it because it will cause problems with warranty.

edit: I will continue with those non-invasive current sensors

Two ways - current sensor on one of the phases, or rotation sensor on the shaft. Perhaps a disk mounted on the end of the shaft, with a magnet on it. Everytime the magnet passes a Hall sensor http://www.digikey.com/product-search/en/sensors-transducers/magnetic-sensors-hall-effect-digital-switch-linear-compass-ics/1967232?k=magnet%20sensor a pulse is created. No pulses, no rotation.

Thank you, I will try to study these more

In what way does it not work with the SCT-013? A quick google search finds this article, which shows you exactly how to connect it to an Arduino.

One thing that may not be obvious from the diagram: only connect the sensor around ONE PHASE. You may need to cut the insulation off a cable or install the sensor inside the switch box to get access to the individual wires. Make sure you double-insulate everything so there's no chance of touching 220v on any wire coming out to your Arduino.

Depending on the pump system piping a better way to detect pump run is with a pressure switch. The advantage to this is that it monitors the entire pumping system. For example, if the motor shaft breaks or the pump impeller fails the motor might be running but there is no pumping so the monitor says everything is OK but in fact there is no warer... Just a thought.

R