Explanation of what an "IT" ground is
In power electrics, IT designates a grounding scheme in which there is a deliberate impedance between the transformer's star point and ground.  It is used to control fault currents and provide a means to alarm on first fault without forcing an immediate shutdown.

See for example Cahier technique no. 178 - The IT earthing system (unearthed neutral) in LV (PDF) for some discussion.

It is popular in applications like hospital operating rooms where the power tripping off without warning is more than a little unwelcome, but is also used in heavy industry where there are steps that must be taken to avoid damage before the plant can be shutdown.