Rolls-Royce Archives
         « Prev  Box Series  Next »        

From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of the reliability of an electrical system's relay switch and ballast resistance.

Identifier  ExFiles\Box 31\1\  Scan202
Date  8th October 1926 guessed
  
-4- Contd.

the same order as that of the ignition apparatus in
respect of its ballast resistance.

Further than this, it is to be noted that the unlike the
functioning of certain other parts of the electrical system,
i.e. if this apparatus does get out of order, except in one
particular way, it does not prevent the system from function-
ing. If the switch sticks on contact we have exactly the
system which we have at present. If the switch sticks off
contact, a very unlikely case, we have the system which we
have at present but with reduced charge. The only vital
element of unreliability would appear to be that due to
breakage of the continuity of the ballast resistance which
is inserted into the field circuit. Should such discontin-
uity occur this switch will go on and off contact alternately
and flashing at the points will be produced, the cutout going
in and out of contact at the same time. But it is no
more likely to occur, carrying as it would, approximately the
same current, than in the case of the similar ballast resis-
tance on the ignition system. Altogether it will be seen
that in adding this other unit we are adding quite a small
proportional amount of possible unreliability.

As regards the gain in better functioning of the
system, this relay switch is definitely arranged in such a
way that it requires considerably more ampere turns of
excitation to open the switch than the amount to which these
ampere turns must be reduced again to allow the switch to
close. There are two excitation coils on the magnetic for

Contd.
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙