SHIPBOARD EQUIPMENT 



Figure 15 shows the shipboard equipment in block 

 diagram. For purposes of description we consider in order: 

 the power supply; the gage-selection control circuitry; 

 digital display and printer; and the analogue display. 



The power to operate all gage packages is derived from 

 a single power supply. A variable transformer is adjusted 

 either manually or automatically to maintain the current at 

 one ampere regardless of the number of gage packages operative 

 in the chain. The power is led to the individual packages 

 through a transformer in each module where the output of the 

 secondary is rectified and used to power the package. The 

 primary windings of all the gage packages in the chain are 

 connected in series. Thus, in the event of a short or open 

 circuit anywhere in the secondary side in a module, the 

 remaining modules will continue to receive power in the pro- 

 per amount. This "fail-safe" arrangement is employed also in 

 the control and calibration circuits described below. 



Approximately 330 volts will be required to operate 128 

 gages with 5000 feet of cable if a conductor of No. 22 copper 

 wire is used for the power. The return wire will be the outer 

 steel armor of the cable or an internal heavy gage lead . The 

 power-supply frequency may be 60 cycles, although 400-cycle 

 power is preferable in that it allows smaller transformers 



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