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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).
Test results for determining the optimal brush position on a 20 hp dynamo with a 48 coil armature.

Identifier  ExFiles\Box 165\6\  img224
Date  9th December 1924
  
RR 239 (150 BKS.) (DB{Donald Bastow - Suspensions} 461-B 12-24)*MP 306975
Y 6003
ROLLS-ROYCE LTD.
INSTRUCTIONS.
To: E.F.C.
Order No: AD 45
Customer's No.: X6003
Date: 9. Dec. 1924

20 hp Dynamo with 48 Coil Armature
Brush position determination
Tests have now been made on dynamo N with the above armature.
Brush positions ranging from 3 1/2° advance to 13 1/2° retard were tried the best all round results being at about 7 1/2°. This position gives a cutting in speed of 810 rpm, a peak output of 14.0 amperes at about 1770 rpm and an output of a little over 7.0 amperes at 4000 rpm as shown on attached curve.
The Commutation is good at this position and incidentally the armature gives this setting in a standard carcase without further alteration.

Signed: [illegible signature]
This Sheet must be filed on completion of the work.
  
  


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