Manufacturing - Special Needs
Manufacturing industries exist to make a product. Typically, machinery dominates the power system load. Assembly lines are a standard part of the program, along with computers to control the processes.
In this environment, you often find ungrounded 3-phase, 3-wire power systems. A short of one phase to ground will not cause a ground fault. The breaker does not trip, so the process does not stop. As long as these systems are well controlled and maintained there are no problems with it being ungrounded.
But, if the system is allowed to degrade over time, wiring errors and failures could cause problems or even safety concerns.
One other special aspect of manufacturing industries is the combination of three basic systems for doing work -- pneumatic, mechanical, and electrical. Ultimately, all three systems involve electricity and affect the quality of power. Don't overlook them as potential problem sources.