Patent GB-190315243-A (GB)
Title: Improvements in Means for Automatically Regulating Electric Currents Generated by Dynamos.
Inventor: WATKINS STEPHEN
Filed: 1903-07-10
Granted: 1904-06-30
Abstract: 15,243. Watkins, S., [Consolidated Railway Electric Lighting and Equipment Co.]. July 10. Dynamos, regulating; electromagnets. -Relates particularly to regulating the amperage and voltage of electric currents for train lighting, such currents being obtained from a dynamo, driven by the car axles, in connection with a storage battery. Rheostats are arranged both in the external circuit and in the field circuit, and are operated by ratchet mechanisms controlled by electromagnets instead of solenoids. Cams are provided which put the armatures of the various electromagnets into their normal position at recurring intervals. Fig. 6 shows in diagram the electrical connections. D is the dynamo armature, F is its shunt field in series with the rheostat R', R is the rheostat for the lamp circuit, and M is a small motor supplied from the dynamo for operating the ratchet mechanism, which runs whenever the lamps are turned on and whenever the dynamo is generating a current of the normal supply voltage. E<1>, E<2> are electromagnets for controlling the position of the pawls of the ratchet mechanism for the rheostat R, and E<3>, E<4> electromagnets controlling the operation of the rheostat R' ; C is the automatic switch for connecting up the dynamo to the lamp circuit when its potential has reached the limit, S is the storage battery, and SW the lamp switch. Figs. 1 and 3 show the arrangement of the mechanism, which is carried in a box-like frame 1, the rheostat R being fitted at one end and the rheostat R<1> at the other. The small motor M drives, through worm gearing, a shaft 5 fitted with eccentrics 12, 12 for rocking the pawl carriers 9, 9<a>, mounted loosely on shafts 7, 7<1> to which are fitted respectively the rheostat arms r, r<1>. On the shaft 7 are mounted two ratchet-wheels 11<a>, 11<b>, with which engage the pawls 10<a>, 10<b>, carried by the pawl-carrier 9, the teeth of the ratchet-wheels being inclined in opposite directions. The engagement of the pawls is controlled by the electromagnets E<1>, E<2>, their adjustablycounterweighted armatures 15<a>, 15<b> being carried on levers passing below pins 17<a>, 17<b> on the pawls and serving to lift the pawls out of engagement with the ratchet-wheels when the current is normal. The pull on the armatures is proportional to the voltage of the current supplied to the lamps, and will cut in or out a part of the rheostat R as required. The rheostat R<1> is controlled in a similar manner. The armature levers are raised into their normal position at intervals by means of cams mounted on and rotating with the shaft 5. Each electromagnet is preferably of a horse-shoe shape, Fig. 7, the armature consisting of two iron plates 15<a> carried by a non-magnetic bridge-piece 14<a>. The electromagnets E<3>, E<4> controlling the rheostat in the field circuit have two windings, both in the external circuit and one in series with the lamps. They are oppositely wound, so that, when the lamps are switched out, the magnets are strongly energized, and the armatures attracted to cause resistance to be introduced into the circuit.