Guide on Shielding, Grounding, and Design Techniques in Factory Automation

Multi-axis motion control servo systems contain digital and micro-processor circuitry that can be affected by Electro-Magnetic Interference (EMI). They also contain high energy switching amplifiers which can generate significant EMI at frequencies from 10MHz to 300MHz. Clearly the potential exists for this switching noise to interfere with correct operation of both the motion controller and any other electronic equipment in the vicinity. While most manufacturers, including ORMEC, are very careful to minimize susceptibility of their products to EMI, complete immunity is not possible. Some responsibility for avoiding EMI problems will inevitably fall to the control system integrator. This guide describes panel layout, wiring, grounding, and shielding techniques that we have found effective in designing and building motion control systems. As in all engineering designs, compromise between the perfect design and what is practical is unavoidable. You may not be able to employ all the suggestions we make. However, careful attention to EMI reduction will minimize startup costs and future operating problems in any system. If you are interested in a more complete understanding of EMI design considerations and techniques, the bibliography at the end of this guide will direct you to authoritative texts on the subject.