Analysis of failure causes and research on improvement measures for external constant magnetic field testing of electric energy meters

The external constant magnetic field test is a pivotal method for evaluating the magnetic interference immunity of electricity meters, with its test results critically determining the metrological accuracy and operational reliability in real-world applications. This study conducts a systematic analysis of failure mechanisms in electricity meters during external constant magnetic field testing, identifying three primary failure causes: (1) structural design deficiencies, including inadequate magnetic shielding design and improper magnetic material selection; (2) magnetic susceptibility of critical components, evidenced by magnetic saturation effects in current sensors and parasitic interference from magnetic elements; and (3) circuit design flaws, characterized by insufficient anti-interference circuitry and defective grounding/shielding systems. Based on the failure mechanism analysis, this study proposes improvement strategies encompassing optimized magnetic shielding design, adoption of high magnetic-resistance materials, and enhanced circuit-level interference immunity. Experimental results demonstrate that material-based solutions outperform software algorithm optimizations in effectively addressing test failures. The enhanced prototype successfully passed the external constant magnetic field test (400 mT ± 10 mT), with all performance metrics fully complying with the IEC 62052 series of international standards and GB/T 17215 series of national standards. This research provides both theoretical foundations and practical guidance for ensuring stable operation of electricity meters in complex electromagnetic environments.