Improvements in Dynamo Electric Machines and in their Application to Secondary Battery Installations.
Year: 1892

page_text: Date of Application, 6th Oct., 1892-Accepted, 12th Nov., 1892
COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines and in their Application
to Secondary Battery Installations.
We EDWARD WOODROWE COWAN of Bracklinn Vicarage Lane Bowdon in the
County of Chester and WILLIAM PAUL JAMES FAWCUS of Derwent Bank,
Keswick in the County of Cumberland, Civil Engineers do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
The object of one part of this invention is to obtain in a simple manner from one
dynamo and one armature winding two currents of electricity simultaneously of
different mean electromotive forces, the one current being alternating and the other
continuous and in such a way that the mean electromotive force of the alternating
current can be varied by adjustment relatively to that of the continuous current
within certain limits to be hereafter described.
The object of the other part of this invention is to apply our improved dynamo
described above to the charging of secondary batteries with a continuous current
and at the same time to supply an alternating current at a lower mean electro-
motive force to incandescent or other lamps in such a way that while the mean
electromotive force of the alternating current supplying the lamps is kept constant,
the continuous current charging the secondary batteries being of sufficiently
greater mean electromotive force can be kept at the proper value and also be kept
constant by varying the resistance of the charging circuit by means of a rheostat
regulated either by hand or automatically.
We effect the object of the first part of our invention in the following way :—
In the accompanying drawing A is the armature and C the commutator of any
continuous current dynamo.
Upon the commutator, but, with the exception mentioned below, insulated from
it we place two gunmetal or copper rings CC. By means of gunmetal or copper
screws we make a metallic connection between one of the bars of the commutator
and one of the rings C C, the other ring we also connect to one of the bars of the
commutator, the position of the bar to which this ring is connected relatively to the
position of the bar to which the other ring is connected determines the mean
electromotive force of the alternating current relatively to that of the continuous
current. If the two bars to which the rings are connected are at extreme positions
opposite each other, the maximum possible mean electromotive force of the alter-
nating current relatively to the continuous is obtained; while if the two rings are
connected respectively to two bars of the commutator next each other the minimum
possible mean electromotive force of the alternating current relatively to the
continuous current is obtained. It is possible to obtain intermediate ratios of mean
electromotive forces depending upon the relative position of the two bars to which
the rings are respectively connected, the number of variations being limited by the
number of bars in the commutator. The alternating current is collected from the
gunmetal or copper rings by means of two brushes A A and the continuous current
is collected in the ordinary way from brushes B B waking contact with the
commutator C.
The field magnets of the dynamo are excited in the usual way with the continuous
current.
We effect the second part of our invention in the following way—
Our improved dynamo is adjusted in the manner above described to give an
alternating current of maximum relative mean electromotive force to the continuous
current. The dynamo is then started and run at a speed to give an alternating
current of mean electromotive force suitable to the lamps on the lighting circuit,
:

page_text: and the lamps are supplied as required by this current. The continuous current
at the higher mean electromotive force is then supplied to the cell charging
circuit and regulated in the ordinary way by means of a rheostat in series with
the cells.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
-claim is :-
1. The construction of a dynamo electric machine substantially in the manner
herein before described and shown on the accompanying drawing, capable of supply-
ing simultaneously an alternating and a continuous current of electricity at different
mean electromotive forces relatively adjustable within the limits hereinbefore
.described.
2. The application of the improved dynamo hereinbefore described to the
-charging of secondary cells and lighting of lamps simultaneously.
Dated this 4th day of October 1892.
EDW. W. COWAN.
W. P. JAMES FAWCUS.