Arduino crash / freeze when ac motor turn on/off

Other Hardware Motors, Mechanics, Power and CNC
1

I'm testing "stressing" a proyect which are a series of relays that are turning on/off 220v devices. Not need to analize the code, (or to show details) because i think that is a electrical problem.

Relevant information:

  • The promini is powered by 12v 300ma trough tl7805 regulator to the Vcc in
  • 6 opto relays powered with external PSU.
  • the code turns on/off relays feeding AC devices: fans, lights, etc.

I have a 220v ac fan motor connected to one relay. Sometimes, when the motor starts or ends, the 16x2 display i2c protocol colapses and later, arduino crashes.

I know that is a common issue this, i read a lot of makers facing this problem.

I read that snubbers can prevent spikes of rapid trasient discharges making the arduino inestable. But, i really dont know how to approach this solution.

Where to insert the "filters / snubbers", in the motor side or in paralel with the relays contacts?
Perhaps the issue is the psu?
Where to start ?

This is the ac fan:

image

Any help regarding to this topic, i would appreciate.
Gabriel

2

I would start with sharing a schematic how you have everything wired up. Without that it's hard to help you.

3

Probably the best solution is to properly dress the wiring and use zero cross solid state AC relays for AC and conversely solid state DC relays for DC. When you post the schematic also show a picture of how it is connected and links to each of the hardware devices technical information. Places like Azon and Allie show sales information.

4

Dears,

I found a solution to this issue.
The problem is EMI interference / voltage spikes comming from the motor.
So, a snubber filter in parallel with the load did the trick

In this case i used:

2uf capacitor + 460 ohms / 1 watt resistor in parallel with the motor, check this:

I'm still testing this solution, but, for now, seems to work. You can also try with a 0.01 uf capacitor with a 200 ohm resistor.

Hope this helps,

5

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