DC generator 
ocean surface 
input 
ocean surface 
vial 
| 20,000 ft 
| 
7 
ocean floor 
spherical 
grounding 
output electrode 
DC motor 
Figure 1. Three-phase AC cable system. Figure 2. DC deep-ocean cable system. 
The greatest inefficiency of the DC system calculated with Joule’s 
equation, P = El, was reflected in the voltage drop across the transmission 
line. Using the equation (Pender, 1949), 
= mie all bo 
| (1 + ) (2) 
where R = interface resistance (2) 
P = environment resistivity (ft &2) 
i} 
b 
Z 
radius (ft) 
depth (ft) 
In the case with Z = 20,000 ft 
thus R = (3) 
Energy losses at spherical grounding electrodes were found to be small and 
losses through the ocean were considered to be negligible because of the 
tremendous ocean volume. Results of the DC calculations are presented In 
