1,500 
1,000 
a 0. 4 wire, n = 25% 
Volts, AC 
no. 00 wire, 7 
n= 50% 
500 
(0) 10,000 20,000 
Depth (feet) 
Figure 3. Voltage loss gradient for three AC cable systems. 
Figures 5 and 6. The system with terminal voltage of 4,160 volts was more 
efficient than the system with terminal voltage of 440 volts. A single-line 
DC system is very compact and efficient but, it has three disadvantages. 
First, this type of system would be very susceptible to short-circuiting to 
the ocean environment anywhere along the transmission line and at bottom 
electrical equipment, because any breakdown in the insulation of the trans- 
mission line results in a direct short. With fish biting and abrasion, insulation 
breakdown could be a major problem. Second, the efficiency of the grounding 
electrodes would be reduced by electrolytic corrosion. Third, power distribu- 
tion and conversion at the ocean floor would be difficult since the DC voltage 
would have to be converted to AC voltage before transformation, or the DC 
power would have to be converted to hydraulic power. 
