Online RatioTransfer Control for CompoundRatio CrossRange CurrentTransformer Energy Metering
Haoyan Fan, Bin Xiao, Yachun Wang, Wei Zhang, Yuanyuan MaABSTRACT
An embedded scheme transfers a compound‐ratio CT set between two certified ratios online using magnetically latching relays: each secondary is always closed through an interlocked metering or shunt contact, so an open secondary is structurally impossible, and the take‐over at a current zero gives ΔΦ ≈ 0. On a secondary physical‐simulation platform, the four‐step sequence takes 40.8 ± 6.0 ms with a 20 ms dead window (≈ 3 Wh missed per transfer, 1.9 × 10 − 8 of the annual volume), while the design inequality K 2 /K 1 ≤ 6 keeps both CTs inside the class‐0.2S limits. Twelve‐month paired field records show +28 860 kWh (+13.04%) of recovered metering energy concentrated in the low‐load months (paired t = 5.3, p < 0.001).