Improvements in the Construction and Working of Dynamos.
Year: 1889

page_text: Date of Application, 28th Jan., 1889
Complete Specification Left, 28th Oct., 1889-Accepted, 7th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in the Construction and Working of Dynamos.
I, ILLIUS AUGUSTUS TIMMIS of No. 2 Great George Street Westminster S.W.
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
:-
The objects I have in view are to construct Dynamos so that they may be driven
at varying speeds and get the potential or force exercised by them and the current
given from them shall remain practically a constant between certain prearranged
points of variation of speed.
With these objects in view which I may effect in several ways-the principle I
desire to carry out is the switching in automatically of one or more resistances at
some convenient position or positions..
The resistances may be of any convenient form and shape (there are a great
number of known ways of making them). They may be inserted as a shunt or
series of shunts either at any convenient point in the field magnet coils or outside
them.
The resistances are switched in as follows.
The dynamo when revolving at a given speed has a potential sufficient to
(1) Light any lamps in circuit.
(2) Charge any batteries in circuit.
In this latter case the dynamo is automatically switched in, by preference.
As the speed of the dynamo, then, increases and the potential of or the current
from it rises to a point approaching where the Lamps or Batteries may be injured.
I switch in one or more resistances by means of an electro magnet or solenoid or any
convenient number of either or both. The resistances reduce the potential and or
current so as to keep them below the dangerous limit and also prevent them rising
to that limit during a given prearranged increase of speed.
•
When a second dangerous speed limit. has been almost reached I switch in further
resistances and so on.
But when the potential and or current fall below the point at which a resistance
was switched in-the, magnet or actuating device ceases to act and the resistance is
cut out.
.
To effect this it is necessary to use magnets or solenoids which exercise a power
that increases in the same ratio (or nearly) as the increase in the resisting power of
the spring or other contrivance which is used to send the armature or rod back to
its normal position.
I prefer to use a long pull magnet and to use such a convenient part of its stroke
that its diagrammatic line is as nearly as possible equal to the increasing resistance
of the spring mentioned above.
The magnets may.be put in parallel or in series and in series with the resistances
thamian
COMPLETE SPECIFICATION.
Improvements in the Construction and Working of Dynamos.
I, ILLIUS AUGUSTUS TIMMIS of No. 2 Great George Street Westminster S.W. Civil
Engineer, 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 objects of my Invention are to construct Dynamos (preferably shunt wound
dynamos) so that they may be driven at varying speeds and yet that the potential

page_text: or electro motive force exercised by them and the current given from shall remain
practically constant between certain prearranged limits of variation of speed.
".
With these objects in view which I may effect in several ways the principle I
desire to carry out is the switching in automatically of one or more resistances at
some convenient position or positions. These resistances may be of any convenient
form or shape (there are a great number of known ways of making them).
may be inserted in series with the Field magnets or as a shunt or series of shunts at
any point or points of the Field magnet circuit.
They
It is well known that the E.M.F. of a shunt machine rises as the speed of its
armature increases. I therefore prefer to switch in the resistances automatically
when the E.M.F. of the dynamo has reached such a value that the current in the
external circuit may be prevented from reaching such a limit as to be dangerous to
the lamps or Batteries that may be in circuit. I switch in one or more resistances
by means of an electro magnet or solenoid, preferably a long pull magnet of any
convenient form or shape, the resistances reduce the current flowing through the
Field magnets and so reduce the E.M.F. at the terminals of the dynamo so as to
keep it below the dangerous limit and prevent it rising to that limit during a given
prearranged increase of speed; When a second dangerous speed limit has been almost
reached I switch in automatically further resistances and so on.
But when the potential falls below the point at which a resistance was switched
in the magnet or actuating device ceases to act and the resistance is cut out.
To effect this it is necessary to use magnets or solenoids which exercise a power
that increases in the same ratio (or nearly so) as the increase of the resisting power
of the spring or other contrivance that is used to send the armature rod back into
its normal position.
The electro magnets or solenoids may be joined up either in series, parallel or
· parallel series, reference to the figures of the diagram will make this plain.
In Fig. 1D representsthe dynamo and F.M. are the fieldmagnets of a shunt wound
machine, M, M are the electro magnets, solenoids or long pull magnets (there may
be a number of these) the coils of which are shown joined in series with each other
and the two magnets form a shunt on the field magnets of the dynamo. R. R¹ aro
resistances the coils of which are connected in series with each other and also in
series. with the field magnet coils, when the armatures of the electro magnet M. M¹
are in their normal position the resistances R. R' are short circuited at the contact
pieces C, C but when the armature or armatures are drawn down the contact
pieces C, C are broken and the resistances R R are inserted in the field magnet
circuit. L represents the lamps in the external circuit.
Fig. 2 shows another arrangement in which the coils of the Electro magnets or
long pull magnets M M are joined in parallel with each other but are in series with
the Field magnet coils, the resistances R R being in series with the field magnet
coils and also with the long pull magnet coils, the other letters are as in Fig. 1.
Fig. 3 shows another arrangement in which the coils of the long pull magnets are
joined in series with each other and are also in series with the resistances R. R¹ and
in series with the Field magnet coils, the other letters are as before.
Fig. 4 is a diagram of an electric long pull magnet-if I use the stroke between
the points a, a¹ it is clear that I can fit a spring (or other resistance) so that the
resistance and the magnet pull shall increase in the same ratio and therefore the rise
and fall of the watt force will switch in and switch out any magnet at (practically)
the same (prearranged) point.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what I
'claim is ==
First The arrangement of long pull magnets, electro magnets, or solenoids with
resistances automatically working in the Field magnet circuit of any dynamo, either
shunt, series or compound wound arranged and operating substantially us and for the
nurnoses herein before described

page_text: Secondly An arrangement of long pull magnets, electro magnets or solenoids
whose coils are connected up either as a shunt to the Field magnet coils or in series
with the Field magnet coils and also in series with the resistances substantially as
and for the purposes described.
Thirdly-A long pull electro magnet or solenoid with automatic cut out contact
pieces and resistance attached substantially as and for the purposes herein before
described.
:
Fourthly The use of an electro magnet or solenoid which has a diagrammatic
pull (as shown in Fig. 4) increasing in an equal ratio (practically) with the resistance
it has to overcome substantially as and for the purposes herein before described.
Dated this 28th day of October 1889
I. A. TIMMIS.