I made a remote (GSM) controlled module for a 3 phase pump close to my friends house. The pump should run at night, and walking the 1km to the switch while they are sleeping is the problem.
The manual switch, switches 3 phases which is put through a 4 wire cable (no ground) to the pump 50 meters away and 20 meters down from the manual switch.
At the pump there is a fusebox and a small box which switches off the pump in case there is no water output detected (the water pressure box). The pump pulls a max of 16Amp, the actual amount I don't know (the fuse is 16amp)
My module switches the 3 phase power using a solid state relay ( Eurotherm RS3DA 30A ). I see that the GSM part works and switches the Solid State Relay on, but the pump does not start.
I am not sure what this causes, I had no way to measure the output, just having a voltage screwdriver to test there is voltage on the output of the relay.
At some point the pump after some resetting of the water pressure box) did work but it would never by just powering the whole thing via the relay. Pulling out the 3phase connectors out of my module and connecting them directly will start the pump without a problem.
(there is some waiting involved after running the pump, you cannot just switch it on and off).
At home I could not realy test the relay except for the GSM module (based on Arduino)
I am not sure why this does not work. Could the solid state relay change the 3 phase in such a way that this happens because of power loss (less Voltage?)
Next time I am there (it is a 12 hr drive) I can bring my voltage meter, but it does only do one phase.
Any other things I should buy and take along to test en compare the module in the real world?
Would it help to put the relay after the fusebox?
Should I look for a mechanical relay for switching the 3 phases? Will that solve my problems, or is it just neater (there is a fuse at the switch uphill as well).
If necessary I could hook into the water pressure module but that costs something in the order of 800 USD (my module was about 120 all in) so if I break that I might loose a friend (and my right to visit their remote place).
Best Answer
You should be able to test this yourself at home using household AC mains live as one of the phases L1, and something like a lamp as the load on T1. Keep the lamp neutral going to the wall. Leave L2, L3, T2 and T3 disconnected. This should be easier to troubleshoot.
Crucially check the Arduino control output is holding a voltage over 4V when you are sinking the 50mA 'holding current' in the contractor. You can measure this by turning on the output and checking the voltage at +terminal of the contractor control pins. The device has the 'indicator LED', zero-crossing logic and three opto-isolators sat on your supply. You may find a small logic level MOSFET is needed to drive it, rather than an Arduino pin.
If your drive is inadequate you may be in the position where some, but not all phases fire, (given the zero crossing detect will stagger the start-up) which is not great for the pump as it will stall but still be dissipating power. So until you fix this, don't leave it running for long periods.