Hallo Raghunathan,

your ADAM_3016 signal conditioner from Advantech very probably uses some sort of isolation amplifier. Some of these techniques to provide isolation are prone to introduce DC offset voltages if isolation barrier is hit by interference. I think this is the case in your application: Your 15kW AC drives and 10kW power heaters produce such a high level of noise, that even a short cable connected to output will pick-up enough interference to cause trouble inside isolation amplifier.

Especially capacitor-coupled isolation techniques are prone to introduce DC offsets. If an ESD event hits these chips, the signal transmission technique over the barrier can even totally collapse for a certain period of time.

A good remedy would be the introduce of a shunt between both sides of barrier which is only acting for HF-interference and ESD events, means something like a capacitor of about 1..10nF paralleled by a varistor or transzorb. But manufacturers are so much focused on maintaining their 'total isolation', that they finally end up with a product which is much more susceptible against common mode interference than it had to be...

To my surprise ADAM_3016 does neither provide a terminal for input signal ground nor output signal ground. So, there's no way to add above components to increase reliability and to decrease interference across internal barrier between input and output. And inserting a soft ferrite alone, as common mode choke, does not introduce sufficient dampening. It's not enough just to add impedance against the interference, you must also shunt the interference away from isolation barrier.

You could try to add 1nF capacitors from each output line to ground of 24V supply and to add a common mode choke between capacitors and panel, so that interference coming from panel is filtered and shunted to ground of 24V supply at ADAM_3016.
Have you had a look at output of ADAM_3016 with a scope? Can you see noise here referring to ground of 24V supply?

Kai