GB295252A - Improvements in or relating to electric generating systems - Google Patents

Abstract

295,252. Batty, D. E., and Associated Equipment Co., Ltd. May 7, 1927. Supplying consuming-devices from variablespeed generators. - A generating system for omnibus and like vehicles, and for other purposes, designed to give the required output at low speeds and to be immune from excessive sparking at high speeds, comprises a prime mover with a large speed range driving a plurality of generating elements each of which gives the required voltage at a different speed. The system may comprise a single machine with two windings and commutators with a single armature and a singel field system. The preferred arrangement comprises an auxiliary generator which becomes operative at about 250 r.p.m., a main generator which operates in parallel therewith from 500 (or 800) r.p.m. and speed controlled switching arrangements to render the auxiliary machine inoperative at 2000 (or 2600) r.p.m. The main machine may have an auxiliary exciting winding carrying the load current of the auxiliary machine. Fig. 1 shows an auxiliary three-brush machine the field circuit of which is closed at 250 r.p.m. by a speed-controlled switch 19. The machine is then connected to the battery 12 through the auxiliary field 16 of the main machine 11. At 500 r.p.m. the machine 11 is cut-in by the magnetic cut-out 13. The shunt field 14 of the main machine has a voltage regulator 15. The output of the auxiliary machine falls off as the speed rises according to the curve 20 in Fig. 2, the curve 21 representing the output of the main machine, and at 2000 r.p.m. the switch 19 disconnects it from the load circuit. In a modification the auxiliary machine is a shunt wound dynamo with a field regulator. Its load circuit is controlled by a magnetic cutout and a resistance is inserted in its field circuit to reduce its output at about 2000 r.p.m. by a speed-controlled switch. More than one auxiliary machine may be employed.