Estimation of capacitive current

Leon
07/31/2025

The capacitive current is mainly determined by the length of the feeder, the cross-sectional area of the conductor, the dielectric constant, the height above the ground, and the rated voltage. The specific estimation methods are as follows:
  • Estimation of capacitive current of overhead lines: For overhead lines of 3 - 35 kV, the capacitance per phase to ground is usually 5000 - 6000 pF/km. Based on this, the value of the single-phase grounding capacitive current per kilometer for lines of different voltage levels can be estimated.
  • Estimation of capacitive current of cable lines: The capacitive current of cable lines is much larger than that of overhead lines and needs to be calculated separately. Its value is closely related to the cross-sectional area, structure, and rated voltage of the cable.
  • Estimation of capacitive current of double-circuit overhead lines on the same pole: The capacitive current of such lines is not twice that of a single-circuit line. When equivalently calculated as a single-circuit line, the formula is: Ic = (1.4 - 1.6)Id (where Id is the capacitive current corresponding to the length of a single circuit in the double-circuit lines). The constant values need to be distinguished by voltage level: 1.4 corresponds to 10 kV lines, and 1.6 corresponds to 35 kV lines.

Leon

Hello! I'm Leon, with 20 years of extensive experience in the power industry. My expertise spans from power distribution equipment to grid operations and maintenance, grounded in robust hands-on and theoretical knowledge. Currently, I focus on sharing insights into electrical equipment fault diagnosis, demystifying complex technical challenges through accessible explanations. I welcome collaboration with industry peers and enthusiasts to collectively explore the intricacies of the power sector.

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