There are several reasons you should have an isolation transformer. They can prevent ground loops and also prevent a device under test from having a DC path to ground (or isolate an oscilloscope from ...
The LPD5030V series are miniature high-isolation transformers featuring 1:1 flyback transformer with 1,500 Vdc (1000 Vrms) winding-to-winding isolation and excellent coupling coefficient of 0.97 or ...