The HV Diagnostics BA75 oil tester is a portable Breakdown Analyzer for on-site testing of transformer oil. The dielectric strength of an insulating oil can be tested in a simple, quick and fully automatic action, without the need to ship oil samples to a test laboratory. The plant operator is in a position to decide ad hoc on the need for substitution of the transformer oil and to initiate respective measures. The BA75 has a bright 2.8” color display for optimal readability and mobility; communications via Bluetooth and/or USB Flash drive possible; built-in printer offers a direct evaluation and reporting of results; direct measurement of output voltage and measurement of silicon oils; and besides the main supply, has a built-in battery pack and an external 12V power supply. The automatically generated test reports are provided in pdf-format and can be stored on a USB stick. With a weight of only 22 kg, the BA75 oil tester is ultra-light and ideal for mobile use. The test voltage is automatically controlled and increased to a maximum level of up to 75 kV rms. Flashover voltage is measured with an accuracy of ±1 kV over the whole voltage range. The extremely short switch off time at flashover is below 5 μs. Thus the pollution of the oil by the electric arc is negligible. In addition, this allows nondestructive testing of synthetic oil, ester oil and silicone oil.