commutator segments and zero brush width. It is clear from Dr. Burtness' paper that the true nature of the problem does not appear under these assumptions.This paper emphasized once more the value of matrix algebra as a tool in the study of systems of linear equations. This simple tool can and should be given to the sophomore student in electrical engineering when he is first introduced to systems of linear equations in the study of network theory.

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a r e r e a l i z e d from t h e c o n c e n t r a t i o n of p o w e r system c o n t r o l a n d i n d i c a t i o n i n a single c e n t r a l l o c a t i o n . T h e a v e r a g e steel works p o w e r system is i d e a l for t h e a p p l i c a t i o n of c e n t r a l i z e d c o n t r o l e q u i p m e n t b e c a u s e of t h e c o n c e n t r a t i o n of s u b s t a t i o n s in a relatively s m a l l a r e a . M o s t existing c e n t r a l i z e d c o n t r o l of steel w o r k s p o w e r systems h a s b e e n p r o v i d e d b y s u p e r v i s o r y c o n t r o l . T o p r o v i d e a d e q u a t e c e n t r a l i z e d c o n t r o l of a p o w e r system, it m u s t b e possible t o p e r f o r m all essential c o n t r o l functions a t t h e i n d i v i d u a l s u b s t a t i o n s from t h e c o n t r o l c e n t e r . Likewise, p o s i t i o n -i n d i c a t i n g l a m p s m u s t c o n tinuously supervise t h e position of devices i n v o l v e d in t h e functioning of t h e substations. C o n t i n u o u s o r selective t e l e m e t e r i n g of essential q u a n t i ties m u s t b e p r o v i d e d a t t h e c o n t r o l c e n t e r . T e l e p h o n e service b e t w e e n t h e c o n t r o l c e n t e r a n d e a c h r e m o t e station for e m e r g e n c y c o m m u n i c a t i o n is essential. T h e choice of controls, l a m p i n d i c a t i o n s , a n d q u a n t i t a t i v e i n f o r m a t i o n to b e p r o v i d e d is t h e m o s t i m p o r t a n t decision m a d e in t h e a p p l i c a t i o n of a c e n t r a l i z e d c o n t r o l system. I t is c u s t o m a r y t o p r o v i d e for t h e c o n t r o l of all c i r c u i t b r e a k e r s in all s u b s t a t i o n s from t h e c o n t r o l c e n t e r w i t h t h e position of all of t h e circuit b r e a k e r s b e i n g c o n t i n u o u s l y i n d i c a t e d b y r e d a n d g r e e n l a m p i n d i c a t i o n s a t t h e c o n t r o l c e n t e r . I n a d d i t i o n to t h e l a m p i n d i c a t i o n s s h o w i n g t h e position of devices c o n t r o l l e d or supervised, it is c u s t o m a r y to p r o v i d e l a m p i n d i c a t i o n s of v a r i o u s a l a r m c o n d i t i o n s for m o s t efficient o p e r a t i o n of t h e p o w e r system. T r o u b l e -d e t e c t i n g devices a r e often g r o u p e d t o g e t h e r a t t h e r e m o t e s u b s t a t i o n to p r o v i d e a c o m m o n a l a r m i n d i c a t i o n if a n y o n e of t h e devices in t h e g r o u p d e t e c t s t r o u b l e . U s u a l p r a c t i c e p r o v i d e s i n d i v i d u a l i n d i c a t i o n s for s u c h a l a r m s as s u b station d o o r , t r a n s f o r m e r differential lockout, t r a n s f o r m e r h i g h t e m p e r a t u r e , o r l o w oil level. I n m o s t t e l e m e t e r e d i n d i c a t i o n s , t h e system o p e r a t o r selects t h e t e l e m e t e r e d i n d i c a t i o n s p e r i o d i c a l l y or as r e q u i r e d b y m e a n s of t h e c e n t r a l i z e d...