The BM11D is used for testing the insulation of high voltage electrical equipment and the wide voltage range also allows it to be applied to low voltage equipment. Generators, motors, transformers, cables and switchgear require effective maintenance and the test techniques available with the BM11D give valuable diagnostic information.

"Spot" Insulation tests are widely used to check on the general condition of electrical insulation, called up in most standards covering equipment design, testing, installation and maintenance. Insulation suffers from gradual steady decline, as well as occasional sudden damage; the effects of dirt, grease, moisture, vibration and chemical attack can be tracked through the recording of polarisation index tests which remove the temperature dependence of raw insulation resistance measurements.