Abstract: A radio frequency isolation system for geographically distance signal sources comprising AC and DC signals which develop differences in ground potential includes a control cabinetry chassis with the DC input signal source being electrically grounded to the chassis at the input side of the cabinetry and a hybrid circuit connected to the chassis through capacitors with the AC input signal being connected to the hybrid circuit for grounding the signal at both the input and output ends of the hybrid circuit to the chassis.

Abstract: A control station for use individually or as an element of a distributed process control system has an improved high frequency isolation and grounding system incorporating a "Chomeric" conductive foil tape on both the cabinet front and back walls as well as on the doors and a V-shaped "Chomeric" conductive gasket placed between the cabinet wall and the door in the area of the conductive tape to insure proper sealing of the door and opening to eliminate all RFI (radio frequency interference) problems and meet European standards for RFI cabinet emmisions. This cabinet also has a grounding system comprising a large area swing clip for removing the door as well as a hybrid grounding circuit to eliminate ground potential differences due to geological variations found in different parts of the landscape since the signals reaching the cabinet may originate at remote locations up to a mile or more from the cabinet.