What Is the Electric Field Inside the Cable Under These Conditions?

August 19, 2023
David Sunnyside

Electricity flowing through the power cord of your electronic devices travels as electromagnetic energy guided by electron activity inside the copper wire. The higher the voltage of the power system, the stronger the electromagnetic field. If this is not carefully controlled, the electromagnetic field can interfere with sensitive electronics and create health hazards, such as cancer, from exposure to high-frequency radiation.

The electrical conductivity of the insulating material in high-voltage direct current (HVDC) cables depends on temperature. Applying a DC voltage induces a non-stationary temperature gradient in the insulation that can cause space charges to accumulate. These charges can damage the insulation and shorten its service life.

In order to determine the potential impact of space charge accumulation on cable performance, it is necessary to probe the distribution of the charges in the insulation. However, the analytical procedures currently used can only evaluate the accuracy of electric field distributions estimated from waveform analysis.

These methods assume that the observed signal is well-characterized, which is not always the case when using pulse electroacoustic test systems in real power cables. The impulse response (IR) of the observation system convolutes the measured signal to distort its shape, thereby making it difficult to observe the details of the charge distribution. Deconvolution processing has been used to reduce the IR effect, but it is not possible to guarantee that each measured waveform accurately reproduces the observed electric field distribution.

This study used a state-of-the-art pulse electroacoustic method to acquire waveforms from 66 kV-class extruded XLPE power cables and evaluate their accuracy for detecting the electric field distribution. A statistical analysis was performed for 81 waveforms of a heavilly loaded cable. The estimation accuracy was compared to the Laplace field evaluated for each of the 81 waveforms.

David Sunnyside
Co-founder of Urban Splatter • Digital Marketer • Engineer • Meditator
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