Current transformers (CTs) are critical components in electrical power systems, particularly for measurement and protection functions in high-voltage systems. However, the performance and operational safety of CTs heavily depend on the quality of their insulation. A common issue encountered is insulation degradation due to aging, humidity, or external disturbances, which can lead to system faults or even complete equipment failure. This study aims to evaluate the insulation condition of a 6 kV CT through insulation resistance testing. The method employed involves measuring the insulation resistance using a megohmmeter with a direct current (DC) test voltage, where resistance values are recorded in megaohms (MΩ) up to gigaohms (GΩ). The test results showed an average resistance value of 145.5 GΩ, significantly exceeding the minimum threshold of 1 MΩ per kilovolt as stipulated in international standards (VDE 228/4). Therefore, it can be concluded that the CT insulation is in excellent condition and is reliably suitable for operation in high-voltage systems.