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RELIABILITY The g r e a t e s t r e l i a b i l i t y problem i n the ABM Power System appeared to be a s s o c i a t e d with the prime mover and a u x i l i a r y equipment. I t was to t h i s end t h a t the r e l i a b i l i t y e f f o r t s of the OCE were d i r e c t e d to develop c r i t e r i a f o r a power system that would meet the s t r i n g e n t requirements s e t f o r t h i n the G u i d e l i n e s . The r e l i a b i l i t y of i n d i v i d u a l prime movers i n the l a r g e r s i z e s s u i t a b l e to power the ABM System was not w e l l documented. An extensive and time-consuming study was i n s t i g a t e d to record and analyze the operating record of n e a r l y a l l s i m i l a r power-generating systems i n the U.S.A. The o r i g i n a l estimate of prime-mover mean- time-between-failure by the most knowledgeable designers of power systems and the manufacturers of prime movers was 300,000 hours. L a t e r , i t was found t h a t a power outage occurred i n i n d i v i d u a l d i e s e l engines an average of once every 600 hours. At t h i s time some component of the system required s h u t t i n g down f o r r e p a i r s . The performance evciluation - i n d i c a t e d the f a i l u r e s occurred i n s m a l l e x t e r n a l items such as o i l - p i p e and water-pipe connections. Repair of the prime movers and a s s o c i a t e d a u x i l i a r y equipment was found on the average to r e q u i r e l e s s than three ( 3 ) hours. Maintenance of the preventive type was found to c o n t r i - bute appreciably to the a v a i l a b i l i t y and r e l i a b i l i t y of a power system. With the a v a i l a b l e instruments f o r scanning the e s s e n t i a l operating parameters, i t was found p o s s i b l e to maintain the prime mover and a s s o c i a t e d a u x i l i a r i e s so as to operate w i t h i n the -4-
