How to isolate high-voltage circuit interference in an electrical power measurement switch (PMS)?

The high-intensity electromagnetic fields generated by the high-voltage circuits (main power supply, motor drive) in a Power Management System (PMS) are the greatest threat to low-voltage systems, making physical isolation the fundamental measure. Isolation includes spatial isolation, magnetic isolation, and optical isolation.

Spatial isolation: A separate high-voltage compartment is installed within the chassis, separated from the low-voltage area by a metal partition (steel plate thickness ≥1mm), continuously welded to the chassis. All cables crossing the partition must pass through a filter feedthrough capacitor or filter connector.

Magnetic isolation: Common-mode inductors CMZ1211-501T and differential-mode inductors PBZ3216E120Z0T are used on the power lines to form a filtering barrier. Signal transmission uses isolation amplifiers (such as ADuM4190) or isolated ADCs.

Optical isolation: Control signals use optocouplers (such as 6N137) or fiber optic transmission.

Furthermore, high-voltage cables use shielded power cables, with both ends of the shield grounded. Low-voltage cables use shielded wires, with the shield grounded at only one end. Through multi-layer isolation, the interference coupling of high-voltage circuits to low-voltage systems can be attenuated by more than 60dB, ensuring the stable operation of low-voltage systems in harsh high-voltage environments and meeting industrial environmental standards such as IEC 61800-3.