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).
Technical paper on the voltage regulation of automotive electrical systems, including different generator types and performance charts.
| Identifier | ExFiles\Box 31\1\ Scan171 | |
| Date | 1st June 1925 | |
| Vol. XVI June, 1925 No. 6 Voltage Regulation of Automotive Electrical Systems By DALE S. COLE¹ MILWAUKEE SECTION PAPER Illustrated with CHARTS AND PHOTOGRAPH ABSTRACT PROGRESS made in the development of electrical equipment to serve adequately the needs of motorbus service is reviewed. Electrical loads on motorcoaches are comparatively high, including the usual head, tail and dash lamps, body-marking and destination lamps and buzzer systems. As more and more electrical energy is used, the source of supply and its control become relatively more important. Not only does the electric generating system have to meet the demands of battery charging, but it should be able to carry the connected load with no battery in the circuit. This means that not only is sufficient energy necessary, but the voltage must be regulated in such a manner that the battery can be charged without endangering the life of the lamps because of excessive voltage, and no flicker in the light from the lamps must be perceptible. All these results must be attained under conditions of variable load, variable speed and the changeable temperatures encountered in service. Voltage regulation is the latest development in the electrical control of an automotive generating system and the author describes it, together with other methods. The 12-volt voltage-regulator employed to accomplish regulation is considered in detail, it being designed to furnish regulated voltage energy to battery and lighting circuits on motor vehicles; to maintain the voltage within the limits required for sufficient, steady and non-flickering light from connected lamps; to assure long lamp-life by preventing excess voltage; and to provide the tapering charge, beneficial to the battery, which results automatically from regulated-voltage charging. The outstanding advantages of voltage regulation are summarized. VOLTAGE regulation is the latest development in the electrical control of an automotive generating system. The very rapid development of the modern motorcoach has been accompanied by many improvements in equipment. One of the most interesting of these is the progress made in electrical generating systems which assures sufficient light to make the luxurious coaches attractive by night as well as by day, whether the vehicle be standing at the curb or running over its route. The universal acceptance of the voltage-regulated system is paralleled only by the popular enthusiasm with which the public has received and is using the highway coach. Lighting loads on motorcoaches are comparatively high, including the usual head, tail and dash lamps, body-marking and destination lamps and loads due to buzzer systems. In some cases, greater loads have been proposed such as electric fans, curling irons on sleeping coaches and even electrical heating of the coach. In addition, a storage battery must be charged. As more and more electrical energy is used, the source of supply and its control become relatively more and more important. Not only does the electric generating system have to meet the demands of battery charging, but the generator should be able to carry the connected load with no battery in circuit. This means that not only is sufficient energy necessary, but that the voltage must be regulated in such manner that the battery can be charged without endangering the lamps from excessive voltage. Further, the voltage on the lamps must be steady, with no perceptible flicker in the light. These results must be attained under conditions of variable load, variable speed and at changeable temperatures encountered in service. THIRD-BRUSH-CONTROLLED GENERATOR It is current practice in automotive installations, at present, to use the familiar type of third-brush-controlled generator for supplying energy to the storage-battery and the lights. The third-brush generator tends to maintain a fairly constant rate of battery charging current at all times. Fig. 1 shows the third-brush generator charging-characteristics, at constant speed, for a large battery. On protracted charging, as the battery takes its charge and its voltage increases, the voltage of the generator tends to increase, keeping sufficiently above the battery voltage to force a fairly uniform amount of current through the battery. The value of the current is affected by the setting of the third brush on the generator. This type of equipment has properly been termed “current controlled,” its chief characteristic being a fairly constant charging-rate regardless of battery conditions. The third-brush generator being available and in common FIG. 1—THIRD-BRUSH GENERATOR CHARGING CHARACTERISTIC On Protracted Charging, As the Battery Takes Its Charge and Its Voltage Increases, the Voltage of the Generator Tends To Increase, Keeping Sufficiently above the Battery Voltage To Force a Fairly Uniform Amount of Current Through the Battery. The Value of the Current Is Affected by the Setting of the Third Brush on the Generator. This Type of Equipment Has Properly Been Termed “Current Controlled,” Its Chief Characteristic Being a Fairly Constant Charging-Rate Regardless of Battery Conditions. This Curve Was Obtained at Constant Speed, for a Large Battery ¹ Research engineer, Leece-Neville Co., Cleveland. 573 | ||