How to adapt an electrical power measurement switch (PMS) to an industrial power grid environment for EMC?

PMS operates in complex industrial power grid environments, facing voltage fluctuations, abundant harmonics, frequent load switching, and strong electromagnetic interference. Its EMC design must be specifically adapted to these conditions. At the power input, a wide-range input (e.g., 85-265VAC) switching power supply should be used, with enhanced filtering: the common-mode inductor CMZ1211-501T inductance needs to be increased (e.g., 1mH), and the Y capacitor capacitance appropriately increased (e.g., 4.7nF). Protection levels should be improved: surge protection must meet IEC 61000-4-5 Class 4 (4kV common mode, 2kV differential mode), using a combination of varistors (e.g., 14D511K) and gas discharge tubes.

For power grid harmonics, the cutoff frequency of the anti-aliasing filter at the front end of the sampling circuit must be set appropriately to avoid sampling distortion caused by harmonics. The communication interface must be isolated and use shielded twisted-pair cable. The chassis shielding requirements are higher, and gap treatment is more stringent. Furthermore, the software needs to incorporate power grid disturbance identification and fault tolerance processing. The PMS should pass rigorous industrial environment EMC testing, such as the IEC 61800-3 (speed-regulating electric drive system) standard, to ensure stable and reliable operation in typical industrial power grids.