EMC differences between field and laboratory settings for I/O modules

I/O modules may pass EMC testing in the laboratory, but problems may still arise in the field, mainly due to environmental differences. Laboratory testing is standardized and controlled, with interference applied singly. However, the field environment is complex; interference may be of multiple types, occurring randomly, and its intensity may exceed laboratory testing levels. Field cabling is often less organized than in the laboratory; cable length, routing, and grounding can introduce additional coupling. Strong interference sources not present in the laboratory exist in the field, such as high-power frequency converters, radios, and switchgear arcing. Modules in the field may share ground with other equipment, forming complex ground loops.

Furthermore, laboratory testing is typically performed on a single module, while in the field, multiple modules are integrated into a system, and interactions between modules can create new EMC problems. To address these differences, firstly, ensure that the modules have sufficient margin during laboratory testing. Secondly, strictly adhere to installation specifications in the field, such as cable separation and shielded grounding. For specific field problems, portable testing equipment can be used for diagnosis to identify interference types and coupling paths, and targeted measures can be taken, such as adding additional filters or adjusting grounding.