The unit is designed to measure the dielectric strength of transformer oil and other dielectric fluids according to IEC 60156, ASTM D877, ASTM D1816. It is a fully automatic device that allows testing according to the procedures defined in these standards, as well as according to the user procedures specified in the appropriate section of the setup menu. Operating principle The core of the unit is the high voltage transformer and electronic modules. The unit operates by gradually increasing the voltage on the secondary winding of the high voltage transformer from zero to the maximum voltage, or to the voltage at which an electric breakthrough occurs in the dielectric fluid in the measuring cell installed on the high voltage contacts of the transformer. The voltage in the secondary winding of the transformer occurs due to the gradual increase of voltage in the primary winding supplied with sinusoidal voltage from the controlled inverter, one of the electronic modules. Voltage increase is managed by a microcontroller through the control inverter. The control inverter is commanded by the unit control module. During operation, AC (50-60Hz) voltage is supplied from the secondary winding terminals through the cell electrodes into the dielectric fluid in the measuring cell. The breakthrough occurs between the electrodes in the space filled with the dielectric fluid. Advantages: automated and accurate measurement of breakdown voltage up to 80 kV; instantaneous (4 μs) disconnection of the test voltage upon breakdown; can work autonomously or in a network with transferring results to a PC, creating a local database, generating reports, plotting graphs and printing results; there is software for the implementation of standard and custom measurement procedures – the device can be used for research purposes; simple and easy to operate and maintain.