Performing high voltage insulation diagnostic tests (power factor, tan delta) on large capacitive specimens like generators, motors, capacitive voltage transformers and long lengths of cable always presents a challenge. Typically, these tests are performed with the aid of a resonating inductor to neutralise the load presented to the test set by the capacitance of the specimen. Unfortunately, these inductors are expensive, heavy and complicated to operate, which means that an alternative approach is desirable.