Mitsubishi HiTec Paper is one of the most prominent specialty paper manufacturers worldwide. Headquartered in Germany, Mitsubishi has been making paper since 1799. With over 500 employees, two paper machines and five coating machines, they manufacture approximately 150,000 tons of specialty paper every year. Their product portfolio encompasses inkjet paper, thermal paper, carbonless paper, label paper and protection paper for flexible packaging. Since the factory produces a large amount of paper, any system failure would result in significant economic loss for the company. As a result, the production equipment at the factory has been fitted with an ungrounded power supply and a Bender insulation monitoring device (IMD).
The advantage of an ungrounded system being used in the factory is that there is no connection between power source (transformer) and earth. This means that the electrical installations still function in the event of a single ground fault. In a classic grounded system, the fault would trip a protective device, shutting off the power supply and halting production. Insulation faults such as this can often be traced back to wet conditions, moisture or mechanical/electrical loads, all of which are high risk factors in a paper factory which uses a lot of water in its processes.