Improvements in Apparatus for Lighting Trains by Electricity and in the Winding and Regulation of Dynamos for this purpose.
Year: 1889

page_text: Date of Application, 18th Dec., 1889
Complete Specification Left, 15th Sept., 1890-Accepted, 1st Nov., 1890
Improvements in Apparatus for Lighting Trains by Electricity and
in the Winding and Regulation of Dynamos for this purpose.
I, CHARLES FREWEN JENKIN of Wistaston Manor, Crewe, in the County of Chester,
Engineer do hereby declare the nature of this invention to be as follows:-
In order to obtain a fairly constant current from a dynamo when running at variable
speeds and required to give different E.M.F.'s when driven from the wheels of a railway
van or carriage I provide the field magnets of the dynamo in addition to their
ordinary winding which is in shunt irom the main circuit with other backwardly
wound coils which are in series with an clectrical accumulator on one of the leads and
I also provide a resistance as a shunt past the coils and past the accumulator so that
the backwardly wound coils are in series with the accumulator but in parallel with the
shunt.
In train lighting I use such or other constant current dynamo on the van or engine
with leads therefrom along all the carriages and with accumulators on each of the
carriages, cach battery of accumulators being in scries with one of the lends.
Proferably I inake the accumulator on each carriage of sufficient power to light all
the lamps on that carriage.
The lamp circuits on each carriage I arrange so that they may by a two way switch
be connected either in series with the accumulator or as a shunt to it.
This arrangement may be used whether the batteries are charged in series or in
parallel. The switches may be moved either at each carriage or from the van or
engine.
During the day when the lights are not required continuously the dynamo is out of
action and the lamps are switched into series with the batteries and leads and the
leads are disconnected from the dynamo.
In the van or engine is placed a switch by which the two charging leads can be
coupled together and a small additional battery or resistance then thrown into tho
circuit or not as desired. When the leads are connected by the switch all the lamps
throughout the train are lighted and are extinguished when the circuit is broken.
The above two-way switches may have a third position in which the lamp circuits
aro disconnected and the batteries are left in series the batteries may then be charged
without lighting the lamps.
In order to be able to regulate the lights I provide each carriage with an automatic
governor by which the number of cells used for supplying the lamps or the resistance
of the lamp circuit may be varied or by which back E.M.F. cells can be cut out or
short circuited or put into the lamp circuit. The motion of the governor may be
determined by the current in the leads or the E.M.F. of one or more of the cells or by
the direction or magnitude or both of the current through the cells or but less advan-
tageously by the current through the lamp circuit.
When the two leads along each carriage have a battery in series with one of them
as above described, I provide one end of each lead with a male coupling and the other
end with a female coupling and I set them so that at each end of the carriage the
coupling on one lead is male and on the other female.
In this way the leads on one carriage can be coupled to the leads on the next
carriage whichever way any of the carriages may be turned and the current will
always pass the right way through the batteries on all the carriages. The two
couplings at each end of a carriage may either be in one piece or separate.
Dated this 177th dav of Denowher 1000

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Lighting Trains by Electricity and
in the Winding and Regulation of Dynamos for this purpose.
I, CHARLES FREWEN JENKIN of Heathfield, Crewe in the County of Chester (late
of Wistaston Manor), Engineer, do hereby declare the nature of this invention and in
what mannor the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
My invention relates to a special method of winding dynamos & of combining
them with electrical accumulators for lighting trains by electricity.
My invention relates to new methods of lighting trains by electricity by means of
dynamos and accumulators carried in the train.
In order to obtain a fairly constant current from a dynamo driven from the wheels
of a railway van or carriage and running at variable speeds & required to give
various E.M.F.'s, 1 provide the field magnets of the dynamo, in addition to their
ordinary winding which is in shunt from the main circuit, with other backwardly
wound coils which are in series with an electrical accumulator & are connected in
series with one of the main leads from the dynamo, and I also provide a resistance as
a shunt past these coils & past the accumulator, so that the backwardly wound coils
are in series with the accumulator but in parallel with this resistance.
The number of turns in these coils, the E.M.F. of the accumulator & the
resistance of the shunt are arranged so that the main current supplied by the dynamo
shall only vary between certain chosen limits while the speed varies a certain
amount.
The action of the above combination of dynamo & accumulators is as follows :—
Suppose the dynamo to be running at the lowest speed for which the combination is
arranged, then the current all (except the shunt current round the magnets) passes
thro' the resistance, the E.M.F. at the ends of the resistance being just equal to
the back E.M.F. of the accumulators. No current passes thro' the backwardly
wound coils.
Now suppose the speed to increase. The E.M.F. rises at the terminals of the
resistance & the current begins to flow thro' the accumulator & the back coils,
thus weakening the field magnets & preventing further rise of current. Thus as the
speed increases the current increases, almost all the additional current flowing thro' the
back coils, until equilibrium is again established.
By suitably proportioning the No. & resistance of the back coils, the resistance of
the shunt, & the number & resistance of the accumulators, the necessary variation in
the current may be made as small as is desired.
In order to get the best results from this method of regulating the current the
dynamo should be worked on what is called the "straight part" of its characteristic
curve.
It will be seen that the E.M.F. at the terminals of the dynamo may be anything
from almost zero up to the full value the dynamo is capable of giving (working as above
described), the regulation of the current will hardly be effected by the magnitude of
the E.M.F. at which it is supplied.
Thus this combination of dynamo & accumulators is very suitable for charging a
variable number of accumulators in series.
Figure 1 shews diagrammatically the connections described above.
a represents the commutator.
b, b
brushes.
"
23
C
"
"
29
accumulator.
backwardly wound coil.
e
"
resistance in shunt to c & d.

page_text: 2. A switch for connecting the lamps in a railway carriage in series or in parallel
with a battery as described.
3. A switch for joining the main leads along a train, with or without a resistance or
extra battery, when the lamps in the carriages are in series with the accumulators, as
described.
Dated this 12th day of September 1890.
C. FREWEN JENKIN.