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).
The calibration of various moving coil instruments before and after testing, with a concluding recommendation.
| Identifier | ExFiles\Box 168\5\ img288 | |
| Date | 17th May 1934 | |
| -2- Ha/Wat.7/M.17.5.34. Cont'd.{John DeLooze - Company Secretary} The subsequent calibration of the instruments however shewed a marked difference to their initial readings. In some cases, e.g. the Ferranti, C.A.V. and Elliot which are all moving coil instruments, the full scale reading shewed a difference of 6 amperes. We give below calibration tables before and after the test which indicate the discrepancy. Calibration before test. ____________________________________________________________________ Master Ferranti. C.A.V. Elliot. Lucas. Weston. Instr. 5 4 4 4.8 4 4 10 8 8 9 7.5 8 20 17 16 17 15 18 ____________________________________________________________________ Calibration after test. ____________________________________________________________________ 5 5.5 6 5 6 7.5 10 11 11 11 11 13.5 20 23 22 23 20 21 ____________________________________________________________________ Our conclusion therefore is that heavy current accessories must be definitely prevented from passing their current through the ammeter. Conversely the range of the ammeter must be increased. Ha/Wat. | ||