The results obtained show that the electric strength of silicone rubber insulated cable can be increased by using a graded construction, when one layer has a high dielectric constant and the other a low dielectric constant. Silicone rubber is easily adapted to this method because the dielectric constant can be varied from 3 to 7.5 by varying the amount of titanium dioxide added to the silicone rubber base. By making use of silicone rubbers versatility the breakdown voltage was increased by 50. The amount of increase in breakdown voltage obtained depends upon the variables mentioned in the discussion of the calculated breakdown voltages. The capacitance also increases along with the breakdown voltage. This variation may or may not be important depending upon the application. Two possible applications of graded constructions are ignition cable and gas-tube-sign cable. Author
Prepared for presentation at the Annual Wire and Cable Symposium (10th), Asbury Park, New Jersey, November 29-December 1, 1961.