Learn OT security

Dear all,
I work as a penetration tester in a Europian country and due to some new regulations coming the world of OT is going to be forced to adapt security. I have never worked with anything OT related nor does the team I am a part of. My question would be if you could recommand me material where I can learn the basics of OT and OT security from? I would prefer if it would be open-source material but …

coming cybersecurity learn ot security penetration penetration tester question regulations security team work world