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).
Comparison of heavy and fine windings for a relay switch.
| Identifier | ExFiles\Box 64\3\ scan0199 | |
| Date | 6th March 1925 | |
| X8650 6th March, 1925. RELAY SWITCH ( SECOND UNIT). X.8650. -------------------------------------- Comparison of heavy and fine windings. Heavy winding. -------------- Minimum current to operate = 135 amperes. No. of turns = 6½ Minimum ampere-turns = 877. Fine winding. ------------- Minimum current to operate = 2.05 amperes. No. of turns = 300. Minimum ampere-turns = 615. EFC/CAP. | ||