Is the working power grounding and enclosure grounding of the instrumentation the same thing? Can it be directly shorted?

It is not the same thing, one is the working ground, one is the protective ground. In the TN-C system and TN-C-S system, in order to make the circuit or equipment to meet the operational requirements of the grounding, such as transformer neutral grounding is the work of grounding; protection of zero is the metal casing of the electrical equipment and the grid zero line reliable connection to protect personal safety of an electrical safety measures. Two are not allowed to short, there will be life safety accidents