Optimization of a High Frequency Current Transformer sensor for Partial Discharge Detection using Finite Element Analysis

High Frequency Current Transformer (HFCT)
sensors are widely used for Partial Discharge detection due to
their versatility, high sensitivity and wide bandwidth. This paper
reports on a Finite Element Analysis (FEA) methodology that can
be employed to optimize HFCT performance. The FEA model
consists of accurate 3D representations of the sensor components.
Two different FEA software modules were used in order to cover
the wide operating frequency range of the sensor. The simulation
computes the frequency response of the sensor in the range
0.3 MHz - 50 MHz for various HFCT geometric and material
parameters, specifically the number of winding turns, spacer
thickness, aperture size and core material. A prototype HFCT
was constructed and the measured response compared with that
of the simulation. The shapes of the responses were similar, with
the simulated sensitivity being higher than the measured
sensitivity by 1 dB on average. The measured low frequency cutoff
of the sensor was found to be only 0.05 MHz lower than that
of the simulation.