hi erik

first i have to get some time to make the new design.
but customer should not shout for stopping the machine.
so some how i need to run the machine and mean while find a solution as suggested by you and all.

i have already decided to go for 4 layer design and started work on that.

i have purchased one coil of 0.5sq.mm wire from the shop and without disturbing it, i connected one end to the 230V AC supply and other end to my SMPS ( whose output is 5V DC).

i told the above only to get an idea of what was going wrong. (Same PCB is working).

i can brief you about the outputs used to drive the relays

there are 24 digital outputs from the micro driven through '574 and an opto to get +24V 2A as output.

i am using this output to switch on a relay ( PCB mounted)

relay terminals are used to drive the 230VAC solenoid.

i have removed the common line 230VAC that is given to all the 24 relays and tested. relays are switched on and solenoids are off. now there is no problem.

relays are two feet away from the micro.
solenoids are 30 to 40 feet away.
snubbers for solenoids are made in a PCB and kept near
relay board. (i am planning to put snubber right across the solenoid).

i have installed SMPS on top of the CPU card. distance between SMPS and micro is 100mm.

my doubt is some spikes are going into the 5V SMPS. how to stop them?. i think i have to go for some good SMPS instead?

is it possible to design a power supply (SMPS) to filter such spikes?

there are three motors 90KW, 55KW, 37KW. on the same machine. whenever any of the motor are on / off nothing is happening. but switching of solenoids are cousing the hanging.

i hope this will give some idea about my project.

Best Regards

Haribabu

PS: strongly decided to go for 4 layer PCB with all guru's help.