During DC testing of insulation, which curve best represents the capacitance charging current?

The capacitance charging current during DC testing of insulation is typically represented by a curve that shows an exponential rise as capacitance charges over time. This characteristic is indicative of how a capacitor behaves when a direct current is applied to it. Initially, the current is high as the capacitor begins to charge, but it gradually decreases as the voltage across the capacitor approaches the supply voltage.

In this context, if Curve B shows a steep initial rise followed by a rapid tapering off, it accurately depicts the behavior of the capacitance charging current during a DC insulation test. The initial surge represents the high initial current needed to charge the capacitance, while the decline reflects the reduced current as the capacitor becomes fully charged.

The other curves would not represent this behavior correctly, whether they depict a steady current or an unexpected pattern, failing to exhibit the familiar charging dynamics of a capacitor under DC conditions. Hence, the selection of the curve showcasing this exponential behavior is crucial for understanding the nuances of insulation testing with respect to capacitance.