Apply to one of the phase 380V through resistor ( calculate the value of resistor so curret is abouth 100mA ) and use AC Leakage Current Sensors.
MY limited experience with irrigation pumps using 3-phase power, in the US, is the power company opens the circuit breakers feeding the transformers during the off season. If this is true in your situation, there is no power at all coming into the irrigation pump controller.Paul
Here's a link to sketch of how the capacitor all-line detection worksIf both detectors (meters) register then the line is intactIf either detector fails to register then the line is brokenNote that when the contactor has closed, both detectors will register full line voltagehttps://postimg.cc/image/bs9vdaubx/
Use a second 3-phase relay which can only be operated when the main power one is 'off'.Then measure resistances between the 3 wires.Allan.
That's not happening here, if you pay the power contract every month, you have power every month...I don 't see why they'd do that, you may still need power for other duties
True.If you want to detect while running ( and if a phase is cut it won't run well if at all ) use a current transformer on each phase and monitor them. Southpark suggested this in post #19.Allan
In the US, the electric rate for irrigation power use is MUCH less than for any other use. So, that power line and meters are not shared with other uses. It is also very seasonal in use. Farmers don't want to pay for nothing for quite a few months. Power companies turn power off for free and reconnect for a small charge. Paul
Here in the East of England ( the Fens) most irrigation is done by large diesel engined pumps, often radio controlled.Drainage ( we're BELOW sea level ) is by fixed electric pumps.Sounds dodgy, but it works.Allan
Would these work after a frequency speed regulator instead of a switch? They don't use just regular switches, they need to control the pressure thru the speed