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).
Letter enclosing four oscillograph records of a dynamo tested under various conditions.
| Identifier | ExFiles\Box 168a\3\ img135 | |
| Date | 23th January 1935 | |
| T.T. 4058 CODES: A.B.C. 4th 5th & 6th (5 LETTER) EDITIONS, A.1. LIEBER'S & WESTERN UNION (UNIV. & 5 LETTER EDIT) & BENTLEY'S. Inland Telegraphic Address. "CRUCIBLE, PHONE, LONDON" (2 words only chargeable) Cable Address. "CRUCIBLE, LONDON" Telephone No. BATTERSEA 2250. THE MORGAN CRUCIBLE COMPANY LIMITED BATTERSEA WORKS, CHURCH ROAD, LONDON. S.W.11. Handwritten text top right: A6099. Handwritten text below address: CAP FT. Handwritten text right margin: Please return Handwritten text left margin: H&S (struck through) West MORGANITE TRADE MARK IN REPLY PLEASE REFER TO Z DEPT Zyc/NM January 23rd, 1935 Messrs. Rolls Royce, Limited, D E R B Y. Dear Sirs, As arranged with Mr. Pignatt when he visited us recently, we are enclosing herewith four oscillograph records of the dynamo tested in our laboratory. These records were taken under the following conditions:- No.1 Entering edge of Negative brush 13.v. 16.5 amps. 3820 r.p.m. " 2 Leaving " " " " " 3 Entering " " " " 12 " 20 " 4770 " " 4 " " " " " The low voltage at the entering edge compared with that at the leaving edge as illustrated by charts Nos. 1 and 2 confirm that at a speed of 3820/ the reactance voltage is very considerably in excess of the neutralising rotational voltage in the short circuited coil. At the speed of 4770 r.p.m. the effect is still more marked, and an actual reversal of the direction of the main current in the brush takes place under the entering edge, as shown by the reversed value of the potential drop. The voltage at the leaving edge has an average value of approximately 8 volts with peaks exceeding 10 volts. Such high values cannot, of course, be dealt with sparklessly by brushes. | ||