EMC research on measurement equipment with floating ground

Earthing loop interference in measurement equipment with floating ground caused by stray capacitance,common-mode voltage through earth wire impedance and electromagnetic radiation was analyzed in this paper.In view of the fact that one ultrasonic level meter failed to pass the electromagnetic compatibility authentication of GJB151A-RS103,electromagnetic compatibility problem caused by parasitic antenna was found in floating ground system.Electromagnetic interference suppression is effectively completed to pass the authentication through interference current transfer,by optimizing low-impedance grounding wire and mounting ferrite bead.This paper can give electromagnetic compatibility problem-solving behavior to measurement equipment with floating ground and equipment to take rigorous radiation emission test for reference.