tain a constant battery temperature in sub- 

 mersibles, the consequences of which will be 

 discussed later. 



Protection from the Power: Faulty COnductor 



protection may lead to short-circuits, while 

 inappropriate cable routing or shielding may 

 result in electromagnetic interference 

 (EMI). In the former situation both the hu- 

 man occupants and the electrical subsystems 

 must be protected; in the latter, only the 

 electrical subsystems must be protected. The 

 causes and results of short-circuits are le- 

 gion. To state the obvious, the ideal solution 

 is prevention through sound circuit design 

 and construction. Unfortunately, a perfect 

 solution is not always attained and devices 

 are required to still the rampaging current 

 before it can cause critical damage. Fuses 

 and circuit breakers provide this protection 

 by interrupting the circuit when it reaches 

 or exceeds a certain amperage level. In the 

 small confines of a submersible, it is not 

 uncommon to have high voltage cables (e.g., 



PRESSURE HULL 



propulsion power) immediately adjacent to 

 cables carrying power or signals from an 

 instrument. In this case the EMI from the 

 high voltage cable may seriously interfere 

 with the output on the signal cable. Shield- 

 ing or adequate physical separation of the 

 two cables prevents such interference. 



Power Monitors: To ascertain the state of the 

 batteries, equipment inside the pressure hull 

 may include one or all of the following: Am- 

 pere Hour Meter to monitor and display the 

 battery current used or remaining. Voltme- 

 ter to read battery voltage or a Ground 

 Measuring System to detect ground currents 

 on the battery and a Megohm Meter to meas- 

 ure ground resistance readings on other ex- 

 ternal equipment. A few submersibles carry 

 none of these measuring/monitoring devices, 

 others carry one or two. Indicators may be 

 included in the Battery Manifold Oil Reser- 

 voir to indicate the level of salt water incur- 

 sion, or in the Battery Vent Valve to indicate 

 when salt water has entered the vent valve 

 reservoir. 



ELECTRICAL 



HULL 

 PENETRATOR 



MAIN POWER 



DISTRIBUTION 



BOX & CIRCUIT 



BREAKER 



POWER TO 



EXTERNAL 



SUBSYSTEM 



J_ 



RELIEF 

 VALVE 

 FOR H, 



COMPENSATION 

 BLADDER 



BATTERY CASE 



HOLDING COMPENSATING 



OIL 



Fig. 7,1 Example of electrical power and distribution arrangements in a submersible. 



315 



