3 Phase AC pump controll by atmega328PB

Using Arduino Motors, Mechanics, Power and CNC
1

Hi Guys,

I will ensure you from the start that I have more than 6 months of googling and tweaking this problem in order to find a fix, but in the end, I have to ask for help.

The system:

I have designed a PCB from scratch to control 3Phase AC pumps for the irrigation systems.
Do not think of something complicated with 3phase speed control and things like that no...is very basic but has created me so many problems.

How it works:

Atmega328 activates a relay which closes the circuit of 24V AC for a CONTACTOR, and this contactor closes the 3phase circuit and starts the motor at full speed... and this how must be.
In total are 8 relays and 8 contactors (1 is the 3phase ac, the rest of them are high-pressure solenoids)

the circuit: [Simplified]

2000×827 138 KB

The problem:

At first, the chip gets reset itself by any turn-on of any contactor from the circuit, and I had added snubber circuits everywhere and also on the contactors and seams this problem is solved like 90 % (some times get reset...but not every time...and I had code if it got to start again. so not big of a deal.

The clip is working on Internal 8mhz crystal (because I was afraid of higher frequencies that might get noticed more easily but I don't know at this point)

The new problem:

The system starts the timer is on the screen (LCD 2004 i2c) and some times randomly ....it FREEZE...the chip freeze with all his ports "Active" means...that my pump it will run all the night until morning where i had to manually reset the board....in order to "revive the chip"...

I have refactored the code in a way to have only a timer and that's it (no menu, nothing...the chip still gets randomly) ....the noise from this motor I think is the cause...but I have a bord made by someone with an Arduino pro mini......a relay and screen and NEVER got this problem (and I have 2 years since I am using that bord....) and it didn't have all my "high noise filters" and still works ...
Maybe is from atmega328PB...
maybe code...

I really don't know...

Thank you for your time,
George.

2

Your problems sure sounds like a lead dress problem. Do you have ALL the signal wires and Arduino power wires well away from any wires that are being switch on and off and any AC power wires.

Your design lacks a "dead man switch" which is a "watch dog" timer that must be frequently reset by the code. If it is not reset within the timeout limit, all external activity is shut down.

Paul

3

Hi Paul,

Thank you for your answer.
Can you be more specific with this "dead man switch" because I have never hear of it

my code when the timer is finished it reset itself in order to restart the entire system...

but...yesterday I have test something if my bord is in close proximity to the motor some times it gets this weird problem with "freeze" but if I have my bord at more then 3 meters away...never got this problem...

4

The original source is from railroad locomotives that used a switch or lever that an engineer needed to pull within some time frame in order to keep the locomotive running. If it wasn't done, the engine would stop, assuming the engineer had died.

Used with modern equipment for the same purpose, safety for those around the machine and safety for the machine itself.

Paul