SELENIUM RECTIFIER APPLICATION' CONSIDKK \TION8 



1479 



output characteristics of stacks on capacity or battery loads. For precise 

 design information, laboratory tests under the specified conditions should 

 be made to determine the actual slope of these characteristics. 



Fig. 8 shows the characteristics for a three-phase full-wave bridge cir- 

 cuit. These characteristics apply to both resistance and battery loa<l8. 



To design a selenium rectifier stack, the following prcK-edure may be 

 used: 



1. Refer to Table I for the dc output voltage rating for the particular 

 circuit application. 



2. For the specified dc output current select the proper cell size from 

 Table II. (If the current exceeds that of a single cell, additional rolls may 

 be connected in parallel.) 



3. The ac input voltage to the stack for the required dc output voltage 

 and current is then obtained from Figs. 6, 7 or 8. 



The following example illustrates this method of stack design. 



Example: To design a single-phase full-wave bridge rectifier stack to 

 supply 1.0 ampere dc at 48 volts into a resistance load. From Table I, 

 the highest dc output voltage for a basic stack is 24 volts for cells rated 



600 



1.0 1.5 2.0 2.5 3.0 

 FORWARD RMS IN VOLTS 



3.5 4.0 



Fig. 4 — Typical dynamic voltage -current charact^ristica of 4-1 -IB stackfl with 

 26-volt cells processed by two different suppliers. 



