load module 



r^^- 



Figure 24. Catenary cable support system. 



Voltage Regulation. A voltage variation limit of plus or minus 5% was 

 established as a design constraint to obviate the need for additional voltage 

 regulation equipment in the load module. In case of constant power demand, 

 voltage regulation equipment can be added at the power source end. However, 

 this criterion is not practical since any load module will have an average load 

 and a peak load, either of which may vary as much as 50%. The allowable 

 voltage drop for a circuit depends on the required regulation or the current- 

 carrying capacity of the cable. The required voltage regulation would be 

 obtained by limiting the voltage drop in the cable system to 5%. 



AC Distribution System. The selection between single-phase and 

 three-phase power was based on the power demand, equipment availability, 

 reliability, and losses. In a single-phase circuit, the power delivered is pulsat- 

 ing and, when the current and voltage are in phase (unity power factor), zero 

 power is deliverd twice in each cycle. 



67 



