4-4. Cab 1e S e l e c t i o n
S e l e c t a p r o p e r 1 у- 1h 1 ck c a b l e t a k i n g into c o n s i d e r a t i o n its
a l l o w a b l e c u r r e n t and the d i s t a n c e b e t w e e n the g e n e r a t o r and
the 1o a d .
Th e load c u r r e n t f l o w i n g t h r o u g h a c a b l e in e x c e s s of its
a l l o w a b l e c u r r e n t may c a u s e o v e r h e a t i n g w i t h r e s u l t a n t b u r n i n g ,
and the use of a c a b l e that is too thin for its l e n g t h иау
r e s u l t in d e c r e a s e d input v o l t a g e to the e l e c t r i c a l i n s t r u m e n t s ,
c a u s i n g t h e m to o p e r a t e w i t h low p o w e r or be I n o p e r a t i v e .
T h e v o l t a g e d r o p a c r o s s a c a b l e can be d e t e r m i n e d f r o m its load
c u r r e n t , l e n g t h and t h i c k n e s s a c c o r d i n g to the f o l l o w i n g s i m p l i
fied e q u a t i o n for t h r e e - p h a s e t h r e e - l i n e s y s t e m :
e = 1/58 x L/S x 1 x \ T 3
w h e r e
e; V o l t a g e d r o p (V), L; C a b l e l e n g t h (ra)
Si C a b l e t h i c k n e s s (mm ) and I; L o a d c u r r e n t (A).
S e l e c t
the c a b l e length and t h i c k n e s s so that the v o l t a g e d r o p
can be h e l d to w i t h i n 5%.
(•
— Coble langlh L ( m )—^
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