Digital Motor Drives Keep Complex Paper Machines Humming

The more sophisticated paper machines may have approximately 100 motors. These motors are controlled by coordinated drive systems. A block diagram illustrates an example of a digital drive system. Such a system includes individual motor controls, operator stations, a master control and a network communications link. A supervisory system can be added for data logging, monitoring and a communications uplink to the factory's process control system. Two diagrams illustrate the need for coordinated drive control. Two photographs show an example of an operator station and a master control station. The advantages of digital drives over analog drives include greater accuracy and consistency, communications, diagnostics, and recipe generation and storage.