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).
Endurance test report for a Lucas ST.900 Starter Motor relay switch No. 760151.
| Identifier | ExFiles\Box 168a\2\ img366 | |
| Date | 26th January 1938 | |
| To By c.to By/RD. 6134. RM{William Robotham - Chief Engineer}/RC.{R. Childs}1/JH.26.1.38. Re Endurance test of Lucas ST.900 Starter Motor relay switch No. 760151. We have now completed tests on the above switch and find the performance of same quite satisfactory. The switch was made to control a current of 200 amperes passing through the windings of a stalled Bentley type motor, and switching 'on' and 'off' at a rate of 10 a minute, 3 seconds 'on' and 3 seconds 'off'. The coil voltage of the switch being maintained at 8.76 volts. results - Volt drop figures were taken with the following MAIN LOAD COMMENCEMENT OF TEST. AFTER 5,000 OPERATIONS. AFTER 15,000 OPERATIONS. RR. Std. 300 amps. Coil volts 7.0 .125 V .072 V .090 V .158 V 200 amps. Coil volts 8.67 .095 .068 .050 .100 100 amps. Coil Volts 10.3 .042 .038 .027 .043 The coil consumption at 6 volts is 2.55 amps. compared with an average figure of 3.3 amperes for the standard R.R. switch. The volt drop varied greatly with the successive operations of the switch, this no doubt due to the arc produced at each break, altering the condition of the contacts. It should be noted that with the exception of one reading, a general improvement in respect to voltage drop occurred throughout the test, also that the volt drop across the Lucas unit is less than that across the standard R.R. unit. | ||