A High-Frequency Voltage Test for Insulation of Rotating Electrical Apparatus

For many years the need for a higher test voltage between turns of individual coils or complete windings has been recognized. To obtain this higher test voltage, high frequency has been introduced. The high frequency used for this test is produced by damped oscillating discharge from a condenser and applied directly to the leads of the coil or winding. Practically any desired voltage can be applied to a coil or winding provided a sufficientty high frequency is used. As a shop method for checking defects in material, or poor workmanship, the high-frequency test method has been found very effective in those classes of windings so far tried. The method used for detecting short circuits on the principle of the radio receiving set are described.