How to achieve CISPR 11 testing for HMI (Human Machine Delivery)?

To ensure HMI products meet CISPR 11 standards, specialized design for industrial equipment is required. CISPR 11 primarily applies to industrial, scientific, and medical radio frequency equipment, categorized into Class A (industrial environment) and Class B (residential environment) based on the operating environment, with Class B having stricter limits. HMIs typically fall into either Class B or Class A.

Key compliance points include: First, controlling major radiation sources such as switching power supplies, clock circuits, and motor drives. Switching power supplies must use complete EMI filters, especially common-mode inductors such as the CMZ7060A series. Clock circuits require proper shielding and filtering. Second, addressing electromagnetic leakage from the chassis by ensuring shielding continuity at gaps, openings, and cable entry points, for example, using conductive pads and shielded connectors. Cables are primary radiating antennas; all external cables should be shielded whenever possible and properly terminated. Good layout and routing rules should be followed during the PCB design phase to minimize loop area.

Pre-testing is crucial; during the R&D phase, spectrum analyzers and near-field probes should be used to scan and identify and rectify any out-of-specification frequencies. For specific frequencies exceeding the standard, targeted filtering or absorbing materials can be added. Echotronics provides a complete set of filtering, shielding, and protection solutions that meet CISPR 11 testing requirements, helping HMI products efficiently meet standard limits.