Ungrounded Power Filter
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
This ungrounded in/out power filter prevents power input noise to an ungrounded machine, due, e.g., to power line transients, and attenuates the output radio frequency interference noise provided by the machine. This reduced size device is mainly applicable when using a double insulation power transformer, such as a direct plug-in transformer. The filter comprises a common-mode ferrite inductor 1 series mounted with both wires connected to the power transformer primary winding 3. The number of windings about the ferrite core is adjusted according to the radio frequency to be attenuated.