Do instrument transmitters and positioners require protective grounding?
Thread Content
Do instrument devices powered by 2VDC, such as instrument transmitters and positioners, require protective grounding? Are there any relevant standards or specifications?
The locator is a 4-20Ma signal. The new standard GB/T3081-2019 requires protective grounding!
Ground the cables that carry signals into the cabinet. Chinese people really stick to traditional ways of doing things; why not seek the most reasonable approach? There used to be a rule stating that systems below 36V didn’t require grounding. Cabinets indirectly specify separate shield grounds (intrinsic safety and explosion protection also require separation) and protective grounds; from a practical perspective, 4-20mA, with one end grounded between the intrinsic safety and explosion protection cabinets is sufficient. Grounding of field instrument equipment is intended to prevent the accumulation of static electricity; in fact, no grounding is required for conductive media, and many flange threads and nuts also do not need to be grounded. Apply what you learn in practice.