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BELL SYSTEM TECHNICAL JOURNAL 



Because of the tendency for the vigor of the corrosive attack on 

 aluminum anodes to decrease as the action continues and because 

 the cell will continue to operate satisfactorily from an electrical 

 standpoint, the best practice for condensers affected by corrosion is 

 to leave them alone unless it is necessary to clear a short circuit due 

 to a buckled plate or a severed anode support. Several cases have 

 been reviewed where condensers are continuing to operate without 

 maintenance, though corrosion was experienced nearly four years ago. 



TIME IN DAYS 



Fig. 16 — Performance of a normal condenser operating continuously at 

 28 volts, direct current 



The Life of Aluminum Condensers 



With respect to the life of normal aluminum condensers, a number 

 of cells have been on trial in actual service installations for more than 

 five years, and several have been operating under test conditions for 

 about eight years. In general, after the capacity of a condenser 

 has stabilized at the value corresponding to the operating voltage, 

 the cell continues to operate at a comparatively constant but slowly 

 decreasing capacity due, perhaps, to a gradual thickening of the 

 film with age. 



The leakage current also decreases with length of service. The 

 capacity, resistance and leakage current of a typical condenser operated 

 for several years is shown in Fig. 16. In this case the fluid had 



