(h)"Government undertaking" means any industrial undertaking carried on—(i)by a department of the Government, or(ii)by a corporation established by a Central, Provincial or State Act, which is owned or controlled by the Government, or(iii)by a Government company as defined in section 617 of the Companies Act, 1956 (1 of 1956), or(iv)by an institution wholly or substantially financed by the Government;