36 



ELECTRICAL ENGINEERING 



of the field. The electrostatic stress is also greater than the 

 average value. 



FIG. 31. 



FIG. 32. 



This condition may be corrected by rounding off the edges of 

 the plates or electrodes as shown in Fig. 32. 



Sheath 



FIG. 33. Potential and potential gradient in a lead covered cable. 



27. Graded Insulation for Cables. Fig. 33 shows a single 

 conductor, lead covered cable insulated with material of dielec- 

 tric constant K. 



R cm. = radius of the conductor, 

 Ri cm. = inside radius of the sheath. 



