Historically, the paper industry has always been an early adopter of new technology. For example, the addition of advanced drives and controls have allowed paper manufacturing machines to produce reliable and quality product more efficiently. High Resistance Grounding is another example and is widely used throughout the industry. However, the process from wood yard to final product is often spread over a large area, making the task of locating faults on these systems time consuming and difficult. Interruption of the process, in particular, interruption to the paper machines that produce large rolls of product at high speed, is expensive and therefore very undesirable. Any type of unplanned interruption, whether from drive or control circuit trips, can have a painful impact on operations.
Riiiippppp!Ripping paper can be gratifying when you are crumpling it up and throwing it in a waste basket. It is not gratifying to see it happen on a paper machine. The process of rewinding or threading the paper to get the process started can be very labor intensive and can waste a tremendous amount of product.
To help prevent issues on the drives and prevent the control circuits from stopping production, ground-fault protection is alarm only. Historically, this was done as an ungrounded or delta 3-phase power source. In the event of a single phase-to-ground fault, operators would continue to run the paper machine and make necessary repairs or troubleshoot issues (stemming from the ground fault) at a convenient time. Repairs could be started at the end of a shift or another day when there are additional electricians or engineers available – and not at 2 am when the fault may have first appeared. This practice of leaving the fault on the system for an extended period of time is a trap that many facilities fall into.