Noise problems in industrial setting

[signalflow]

Anyone know the best most effective way to filter out contactor noise and AC motor noise on board? The noise is coming in through at least 2 ways: 1) through the step-down transformer that powers the circuit and 2) through the relays driving the AC motors, etc.

I am powering 240V contactors and AC motors and using the same 240V lines through a step-down transformer and simple switcher power supply to power 5V and 3.3V chips.

The problem is that I get a lot of electrical noise in the system when the contactors turn on or off and when the AC motors turn on/off.

I am running the stepped-down power lines through a common-mode choke. I also have bidirectional TVS diodes across the stepped down voltage and from 5V to gnd and 3.3V to gnd...but still getting noise problems.

Thanks for any help.

 

[vinodstanur]

I will power the 3.3v and 5v chips from an RC filter if the chips are not taking too much current.