Arduino, Relay and Ethernet behave volatile

[palisekcdur]

I am developing unit for garden irrigation. There is Arduino mega 2560, ethernet module W5500, RTC module DS1302, 6 relay module and this is supplied by 5V 4A. One of the relay is for 230V AC for transformer 24 V AC and others are for 1 to 5 solenoid. I thought it is done, everything was tested on my table. Relays was working like it is programed, also ethernet managing worked, everything all right. But when I connect 24V AC solenoids arduino begin behave strangely. Ethernet loses connection and relay are randomly flickering or RTC loses right time. Solenoids are cca 40cm far from arduino box, and transformer is also alone out of arduino box, cca 30 cm. I tested it again and again. Even when everything is connected, ethernet is working till any relay is switch on. So when 24VAC began flow through the box ethernet began volatile behave.

Thanks for each idea.

see schem and picture of the arduino connection
zavlahy schema.pdf (1.7 MB)

[paulpaulson]

@palisekcdur

But when I connect 24V AC solenoids arduino begin behave strangely.

Did you install free-wheeling diodes to the solenoids?

[palisekcdur]

I didn't. I didn't know about this, OK, I will study it and install it. I hope this is it. Thanks much.

[paulpaulson]

@palisekcdur

But when I connect 24V AC solenoids

I have to withdraw my advice.

Many thanks to Paul_B

[palisekcdur]

@paulpaulson

free-wheeling diodes

Yes, free-wheeling diodes is solution for DC not for AC, so not for my issue

[TomGeorge]

Hi,
Have you got ALL your 240Vac and 24Vac wiring away from the other wiring?
Don't run your AC wiring next/amongst your low voltage/signal voltage..

If that folded length of blue cable is your ethernet, I would not have it draped over the AC wiring that has inductive switching currents in it.

You might need to Google;

AC inductive snubber

To help the inductive switching current problem.

Thanks.. Tom..