In order to exploit horizontal time-harmonic electric dipoles to model shaft rate electric field of practical vessels,the magnitude and location of equivalent source need to be determined.Aimed at vessels mounting the impressed current cathode protection system,the fact that the equivalent source is superimposition of two directionally opposite horizontal time-harmonic electric dipoles is clarified by analyzing the underlying physical mechanism of shaft rate electric field.On the basis of the former conclusion,a practical calculation method of equivalent source magnitude of shaft rate electric field was proposed,which means that the magnitude can be obtained by combining source magnitude of static electric dipole inverted from measured static electric field with the ratio coefficient between the maximum value of shaft rate signal envelope and that of static electric field signal.Besides,the location of equivalent source is identical to that of static electric dipole.The effectiveness of the proposed method is validated by the vessel model test.%为了利用水平时谐电偶极子对实际船舶的轴频电场进行建模，需要确定等效偶极子的源强度和位置。针对安装有外加电流阴极保护系统的船舶，通过分析轴频电场产生的物理机理，明确了等效源是两个方向相反的水平时谐电偶极子叠加的结果。在此基础上，提出一种轴频电场等效源强度计算的实用方法，即可通过反演测量静电场得到的静态偶极子源强度、轴频电场信号包络最大值与静电场信号幅值的比例系数综合确定，且等效源位置与静电场偶极子的位置相同。船模试验证实了所提方法的有效性。
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