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).
Comparing the resistances of field and armature windings for C.A.V., Lucas, and R.R. self-starter motors.
| Identifier | ExFiles\Box 34\3\ Scan141 | |
| Date | 14th March 1918 | |
| X.2642 To BY/HSO. from EFC. c. to By.{R.W. Bailey - Chief Engineer} EFCB/T14.3.18. X.3247 - C.A.V. SELF STARTER MOTOR. A.510. X.3161 - Lucas " " " X.2642 - R.R. " " " With reference to Mr. Royce's request that we should compare the weights of copper used on the field winding and armature winding of these several motors, we give below a summary of the particulars of the resistance which we have already given in several reports. Will you kindly see what you can do as regards determining the weights of copper more particularly on the field windings, from these particulars:- Resistances of field windings:- C.A.V. Motor.- (4 coils. We now think from these figures that these are all in parallel, but will ascertain this). .0039 ohm. Lucas Motor. - (4 coils - all in parallel) .0031 ohm. R.R. Motor. - (4 coils - all in series) .021 ohm. (This we have now confirmed). Resistances of armature windings from com: segment to com: segment:90°C away:- C.A.V. Motor - .0086 ohm. Lucas Motor - .0089 ohm. R.R. Motor - .0119 ohm. (similar figures for the other two wires). not yet ascertained. (45 slot armature. Will you also kindly let us know from your measurements what the respective air gaps should be in these three motors. EFC, | ||