The aviation sector is one of the main contributors to greenhouse gas emissions and there is a need to develop more-electric aircraft (MEA) that are operationally efficient. In traditional aircraft, the limited number of electrical systems operate at low voltage. The next generation of MEA will operate at voltages of above 1 kV to facilitate the transfer of significant levels of electrical power in an aircraft. However, the higher voltage and frequency levels will lead to an increased chance of partial discharge (PD) degradation in the insulation systems. Therefore, it is critical to have an accurate method of PD detection available for use in these new aircraft. Conventional PD detection methods are optimized for 50/60 Hz applications in the power industry and can be disturbed by harmonics generated via power electronic devices operating at high frequency. This paper explores a bespoke PD detection technique developed using a Sagnac optical fiber sensor capable of measuring the frequency-dependent PD information. Tests were conducted in the 50-1000 Hz range in which existing variable frequency AC power systems are being used in MEA. The results demonstrate that the increasing frequency will have an adverse effect on PD and must be considered in MEA design.