Hello aspirant,

PSU hires M. tech graduates from IIT/IISC not only from mechanical branch, but also from other branches if they've qualified the GATE exam or any other exam conducted under the government. PSUs like ISRO also conduct their own entrance exams for recruitment and after the candidates qualify the entrance level exam, personal interview takes place so as to select the eligible candidates. Mostly, in recruitment entrance exams of PSUs, the subjects usually consist of 80% of technical studies, and the rest 20% consist of general English, aptitude, current affairs, critical reasoning, verbal & non-verbal reasoning.

Hope, you got the answer.