Occasionally you come across some unusual situations when setting up measurement systems. The author once had to set up a system to register the vibrations and strain supposed to be present in a contactor that operated at a voltage of 25 kVAC. Power Supply with High Voltage Isolation Circuit Diagram: One of the biggest problems with this project turned out to be the power supply for the measurement system. Since it required a power of about 30 W it wasn’t possible to use batteries since the system had to operate for many hours at a time. A logical solution would seem to be to use an isolating trans-former, but still.25 kVAC means a peak volt-age approaching 40 kV, and on top of that you would have to include a safety margin. In addition, everything that is connected to high voltage lines should also be able to withstand lighting strikes! Consequently the isolation should be able to cope with a test voltage of 150 kV, which is a lot to ask of the isolating material. After