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).
Analysis of a voltage regulator's performance concerning the effects of speed and temperature on battery charging.
| Identifier | ExFiles\Box 31\1\ Scan104 | |
| Date | 2nd February 1921 | |
| -3- regulator suitably set and connected to charge a battery in a given condition (e.g. fully charged) the amperes delivered rise considerably with rise of speed with the field current coil in circuit. For instance, we found the current to rise from 3 amperes to 11 amperes within the regulating range (without temperature variation) with the regulator field current coil in circuit. On omitting this coil from the circuit and re-adjusting the regulator suitably, we found the amperes to vary only from 3 to 4 within the regulating range. (N.B. It would be expected to increase by an amount approaching one ampere owing to the reduction of the field current by this amount in the main compound coil). Hence it would appear that if the field current is led round the regulator core at all, the coil should be wound with a few turns in a demagnetising direction so as to level up the natural tendency of the voltage to rise in the purely volt coil operated case. This being done and a suitable amount of compounding being provided, we should have a control which is almost entirely independent of speed within the regulating range. There still remains, however, the effect of temperature of the volt coil. On this particular instrument we found that with rise of temperature, the operating voltage was appreciably higher as would be expected, and the current delivered to a battery in a given condition at the same speed was considerably more, whether the regulator field current coil was omitted or not. To compensate for the effect of temperature, it would be necessary to rearrange the volt coil circuit with a relatively large amount of zero temperature coefficient wire so that the magnetising effect was practically identical for the same voltage whatever the temperature. In investigating any form of external regulator control, we set out with the idea of finding how the open circuit regulated voltage depends upon, firstly, speed and secondly, temperature. The main compounding coil having little or no effect in this case, the aim should be first to evolve a system in which the voltage is the same for all conditions of speed and temperature. It would then be found that when set to operate on a battery in a given condition, e.g. fully charged, the current delivered to the battery would likewise be the same for all conditions of temperature and speed within the regulating range, and can be made suitably small for the fully charged condition by suitable adjustment. Beyond this point, the amount of compounding would then have to be chosen to suitably limit the dynamo output with the battery in a very low condition. EFC. | ||