Hello guys,
Im working on projects for controlling relays to switch on three phase contactor for induction motors, im using mechanical relays with opto-isolation meaning the power supply for arduino and the relay is different, im also looping the wires that are going inside the relay around ferrite cores, until now i have reduced the electromagnetic interference from reaching arduino but not completely, do you have any suggestions please?!
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The code is completely perfect, without the motors connected, the arduino works normal
Hawre-balak:
Hello guys,
Im working on projects for controlling relays to switch on three phase contactor for induction motors, im using mechanical relays with opto-isolation meaning the power supply for arduino and the relay is different, im also looping the wires that are going inside the relay around ferrite cores, until now i have reduced the electromagnetic interference from reaching arduino but not completely, do you have any suggestions please?!
——
The code is completely perfect, without the motors connected, the arduino works normal
More information is always required!
Are the contactors inside grounded metal enclosures? Is the problem occurring when the contactor is closed or when it is opened? Are the control wires between the Arduino and the relay twisted pairs before going into the ferrite cores?
What exactly are the symptions of the RFI?
Paul
An industrial environment like that really forces you to shield everything, boxes and cables, and keep the sensitive logic well away from the noisy high currents and voltages.
Paul_KD7HB:
More information is always required!Are the contactors inside grounded metal enclosures? Is the problem occurring when the contactor is closed or when it is opened? Are the control wires between the Arduino and the relay twisted pairs before going into the ferrite cores?
What exactly are the symptions of the RFI?
Paul
I have enabled the watchdog timer to trig in every loop, and the RFI causes the arduino to stop working and then it restarts, the only time the arduino stops is when the contractors get closed or opened, only the wires that are going inside the relay are looped around ferrite cores, the contactors are not inside metal boxes because there is not enough room to shield them.
Im also an electrical and electronics engineer and have worked a lot with microcontrollers but this problem is driving me crazy!
Hawre-balak:
I have enabled the watchdog timer to trig in every loop, and the RFI causes the arduino to stop working and then it restarts, the only time the arduino stops is when the contractors get closed or opened, only the wires that are going inside the relay are looped around ferrite cores, the contactors are not inside metal boxes because there is not enough room to shield them.
Im also an electrical and electronics engineer and have worked a lot with microcontrollers but this problem is driving me crazy!
Then you seem to have covered all the more obvious solutions. But, have you added small bypass caps to each active Ardiuno lead? Both input and output.
My first Arduino project was assembled and tested on my work bench at the plant. Have an 18 inch florescent light above the work space. Whenever I turned the light on, the Arduino would die. Had to work with light off, but have lots of light from ceiling lights.
Paul
Paul_KD7HB:
Then you seem to have covered all the more obvious solutions. But, have you added small bypass caps to each active Ardiuno lead? Both input and output.My first Arduino project was assembled and tested on my work bench at the plant. Have an 18 inch florescent light above the work space. Whenever I turned the light on, the Arduino would die. Had to work with light off, but have lots of light from ceiling lights.
Paul
Thanks paul
I only have 10uF capacitor on the arduino 5v and GND, is it ok if i put the same type on the input and outputs?
Hawre-balak:
Thanks paul
I only have 10uF capacitor on the arduino 5v and GND, is it ok if i put the same type on the input and outputs?
Definitely NOT. IF you can't get proper small value capacitors, you can make some by twisting two insulated wires together (not connected in any way) and attaching one wire to the input pin and the other to ground. The longer the twisted wires, the greater the capacitance.
Paul
A really full-on test is to have one of those toy spark generators (tesla coils) nearby ..... somewhere in the room. It can even be many metres away - even 10 metre away. They have caused issues with some sensor readings (eg. arduino with sensors), and maybe even micro-controller lock-ups.