Year: 1888

page_text: Complete Specification Left, 11th Jan., 1889
Complete Specification Accepted. 16th Feb., 1889
I, GEORGE PITT of Sutton in the County of Surrey, Gentleman, (a communication
to me from abroad by Cuenod, Sautter & Co., of 10 rue Voltaire, Geneva, Switzerland,
Electrical Engineers;) do hereby declare the nature of this invention to be as
follows:-
The principal difficulty experienced in the commercial employment of electricity
consists in the fact that up to the present time it has been almost impossible to obtain
a practically automatic regulation of the electro motive force in derived circuits or of
intensity in series circuits. Usually it is necessary to regulate by hand the changes
resulting from irregularity in the speed of the dynamos and other causes.
The automatic regulators employed up to the present time present serious incon-
veniences in practice in consequence either of their delicacy or of their small
sensibility or of slowness in action which causes periods or oscillations of intensity.
In fact it usually happens that in consequence of magnetic retardation the regulator
is obliged to pass far beyond the point corresponding to a new régime and then
the current by exceeding slightly its normal intensity which brings back the
regulator until it passes the normal point in the other direction. From this results.
a series of oscillations of current which in the best regulators go on decreasing until
complete regulation is attained.
The object of my invention is to avoid this inconvenience by means of an apparatus
which can never pass the point strictly necessary for the regulation and to do this
without sacrificing the qualities of solidity and sensitiveness which apparatus of this
sort ought to possess.
My invention consists in principle of a rheostat governed by a solenoid (or other
apparatus fulfilling the same end) with the intervention of any driven mechanism in
such manner that the position of the moving contact of the rheostat may be intimately
dependent upon that of the core of the solenoid, that is to say, that to each position of
the core there always corresponds a position of the movable contact as if they
were mechanically connected. The core of the solenoid is left absolutely free
in its movements and acts only to direct a current into a relay or an electro-
motor.

page_text: The annexed drawing clearly explains my invention. Figure 1 is a diagram
showing the principle of the apparatus. This principle applies to all apparatus
constructed in accordance with the invention.
In Figure 1 the connections of the wires are arranged for the case of maintaining
a constant electro motive force in a dynamo machine excited by a derived circuit.
S is a solenoid traversed by a current derived from the terminals b b. This
solenoid of large resistance attracts more or less a soft iron core n n which is half
within it. The core which is freely suspended controls a lever provided at its
extremity with a double contact. The driving shaft K actuated by the pulley P
gives motion to the two friction cones ff. This driving shaft K in addition to its
movement of continuous rotation can be displaced mechanically in the direction of its
axis, so that the cones ff may alternately drive the wheel in one direction or the
other according as for f¹ is in gear.
This longitudinal movement is brought about by the attraction of two electric
magnets a al acting upon the axis K by means of an armature and a lever 1. It is
obvious that this lever is not indispensable and that the electro magnets a a¹ may
control K directly acting either upon one or several discs or pieces of iron fixed
upon K and serving as an armature. The wheel is keyed upon an axis carrying a
screw v or other gearing operating the lever and the movable contact g. The
double lever is pivoted at z and at the extremity of 12 are two insulated contacts
connected electrically with a and a. These two contacts have their counterpart
upon which is the lever of the solenoid. ₁₁ are resistances of which a
variable number may be put into the exciting circuit of the dynamo by means of g.
This being so, the current can pass according to the position of the solenoid either
through a by c, or through a' by c¹. In the first case will be in gear and will
move vg in one direction and in the second case it is f¹ which will drive vg in the
other direction.
Suppose now that the tension lowering c¹ allows the current to pass in a¹.
Immediately the contact g will move towards thus removing resistances from the
derived circuit of the field magnets and the tension will rise. But at the same time
the lever descending the contact c¹ will shortly leave the lever and 12 will cease to
move. If the tension continues to fall the contact c¹ will bo re-established and
immediately and g will move in the same direction until the interruption is again
produced and so on in the two directions the two levers always taking a relative
position as if they were mechanically connected and never can the contact g pass
beyond that corresponding to exact regulation.
Dated this 16th day of October 1888.

page_text: I, GEORGE PITT of Sutton in the County of Surrey, Gentleman, (a communication
to me from abroad by Cuénod Sautter & Co., of 10 rue Voltaire, Geneva, Switzerland,
Electrical 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 present invention has for its object a combination of apparatus intended for the
automatic regulation of electric currents.
I give to my new apparatus the name of "automatic current regulator."
Up to the present it has been almost impossible to obtain a perfectly automatic
regulation of electro motive force where current is supplied, in derivation or of
intensity where the supply is by a circuit in series. Generally it has been necessary
to compensate by hand for the differences arising from irregularity in the speed of the
dynamos or other causes.
The automatic regulators employed up to the present time present serious incon-
veniences in practice in consequence either of their delicacy, or of their small
sensibility or of the slowness of their action which causes periods of oscillation of
intensity.
The object of my invention is to avoid these inconveniences by means of an
apparatus which never overruns the point strictly required for regulation and which
at the same time possesses those qualities of solidity and sensitiveness which an
apparatus of this sort should present.
My invention consists in. the application of a rheostat controlled by a solenoid or
equivalent apparatus by the aid of an external force from any source in such a
manner that the position of the moveable contact of the rheostat may be intimately
dependent on that of the core of the solenoid, that is to say, that for any given
position of the core there is a corresponding determinate position of the movable
contact as if the two were mechanically connected. The core of the solenoid is left
entirely free in its movements and operates only to direct a current into a relay or to
an electric motor.
In order more fully to explain my invention I will describe the annexed
drawings.

page_text: Figures 5 and 6 are detailed views of certain parts of the regulator. These figures
are one-third of the actual size of the parts.
Figure 7 is a vertical section of the solenoid full size.
Figure 8 is a diagram illustrating the operation of the rheostat.
Figure 9 is a diagram illustrating the passage of the principal current and of the
exciting current in the apparatus.
Figure 10 is a diagram illustrating the manner of employing the current itself to
actuate the apparatus by means of a motor and of a current reverser.
Figure 11 is a diagram showing an arrangement which can be adapted to that
indicated in Figure 10.
In these figures G is the upper table of the rheostat and G₁ the lower table. Upon
the table G is fixed the frame T in which the different parts of the apparatus are
mounted. 9, 9, 9, 9, are four columns which support the upper table G.
S is a
solenoid traversed by a current derived from the terminals bb of a dynamo electric
machine. This solenoid, which is of high resistance, attracts more or less a core of
soft iron n which is half engaged into its interior. This core is freely suspended, as is
shown in Figure 7, and it controls a lever L furnished at its extremity with a double
contact. The lever L pivots upon an axis mounted between the bearings 13 13
(see Figure 6). It is supported by a coiled spring which serves also to adjust the
lever and consequently the apparatus according to the tension to be maintained. This
regulation is made by means of the nut V. In addition an endless cord gives motion
to the grooved pulley P which it turns in the direction of the arrow (Figure 2).
This pulley is fixed upon an axis K on which are mounted two friction cones f, f¹.
This driving axis besides the movement of rotation, which is continuous, can be moved
longitudinally so as to alternately bring one or other of the friction cones f, f', into
contact with the horizontal wheel E. This wheel is mounted upon the end of an
axis e furnished with an endless screw e¹ (Figure 1). This wheel, and consequently
the endless screw e¹ turn in one direction or the other according as it is driven by the
friction cone for by the cone f¹.
The longitudinal movement of the axis K is determined by the attraction of two
electro magnets a, a, and a, a', (attracting alternately a disc armature K¹ mounted
upon the end of the axis K.
The wheel E by means of the screw e¹ drives a toothed wheel I mounted upon an
axis i upon the anterior end of which is fixed a disc d upon which are the blades D. D,
forming the movable contact of the rheostat. Upon the axis i behind the whee! I is
fixed a small toothed wheel or pinion 12 (Figure 5) which gears with the plate or
toothed lever H pivotting at h. Upon this plate are fixed two adjustable contacts C, C¹
and two stops or abutments A, A', also adjustable. The two contacts C, C¹, have their
counterpart upon the lever L of the solenoid at l l.
RR are resistances of which a variable number can be put into the exciting
circuit of the dynamo by means of the double blade D, D: The diagrams Figures $
and 9 indicate clearly the passage of the currents in the apparatus. The exciting
current is represented by dotted lines. The derived current upon the principal circuit
is represented in Figure 9 by continuous lines. In these figures the arrows indicate
the direction of the current.
The exciting current led away from one of the brushes of the dynamo reaches the
apparatus by the terminal 6, from there it goes to the part D of the double blade or
movable contact of the rheostat and passes according to the position of this blade to
the contacts u either directly by the resistance R" or by the resistance R¹ and the
resistance to the field magnets of the dynamo, and passing through the coils of
these magnets it reaches the other brush..
The current derived upon the principal circuit reaches the apparatus by the
terminal 4 passes first in the solenoid S and the two larger resistances R R in tension
and returns by the terminal 3 to the dynamo. Secondly. the current passes in the
electro magnets from the terminal 4 by the lever L, one of the two contacts CC¹
the terminal 1 or 5, the electro magnets to the terminal 5 and the dynamo.

page_text: The stops A A¹ are abutments serving to interrupt the current in the two extreme
positions of the lever L.
The current passes then according to the position of the core n of the solenoid,
and consequently of the lever L either through the bobbins a, a, by C or by the
bobbins a, a, by C. In the first case the armature K¹ will be attracted by a, a, a
putting the cone f¹ into gear with the wheel E and thereby moving the lever H in
one direction. In the second case it is f, which will engage, moving the lever H
in the other direction.
Supposing now that the tension falling allows the current to pass in a¹, a',
immediately the blade D D will move in the direction of the arrow (Figure 9), thus
cutting out resistance in the circuit of the field and the tension will rise, but at the
same time the lever H'turns upon its centre, the contact C³ falling breaks contact
and H ceases to move. If the tension continues to fall the contact C is re-established
and immediately the lever H and the blade D D move in the same direction until the
interruption is again brought about, and so on in either_direction. The two levers L
and H always assume relative positions as if they were mechanically connected and
the contact D D can never pass beyond the point corresponding to exact regulation.
The blade D, D is formed in two parts connected by a supplementary resistance R¹,
as is shown in Figure 9, intended to divide the difference of action between one
resistance R" and the next. If one of the branches of the double blade D, D, is upon
a contact u and the other upon the next contact the current has two roads of equal
resistance and so is only weakened to the extent of a half.
Figure 10 shows an arrangement intended to work in places which are not provided
with motive power or where it is desired to utilize the current itself. The principle
of the apparatus is the same, the position of the contact lever follows exactly that
of the lever of the measuring apparatus in consequence of the mobility of the
contacts CC. These last are arranged to control either directly or by the intervention
of a relay composed of two magnets a, a¹, a current inverter Z acting upon the
armature of an electro motor, so that this turns in one direction or the other according
as C or C establishes the contact.
The diagram (Figure 10) indicates the connections of the current in the case of the
regulation of the electro motive force of the source of current Y.
Figure 11 indicates an arrangement which admits of the suppression of the relays a a'.
RR are two resistances connected in series from which two derived circuits are
taken to feed the armature of the motor Y. They are of equal value; one of the
connections is made at their point of junction and communicates with one of the
brushes of the motor. The two other connections are made at the two free extremities
and terminate in the inverter. The lever L is connected to the second brush; the
principal current, as the figure clearly shows, is directed at the same time upon
the resistances and the inverter. Thus L having at all times but one contact to effect
is entirely free to move and may control the inverter directly.
I do not limit myself to the details of execution described.
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 :-
1. An automatic apparatus for the regulation of electric current composed of a
rheostat of which the moveable contact is connected mechanically with a determining
apparatus such as a Volt meter, galvanometer, Ampère meter or other measuring
apparatus serving the same object in such a manner that every movement thereof
determines a proportional movement of the movable contact without interfering with
the freedom of action of the determining apparatus.
2. An automatic current regulator composed of a rheostat furnished with a movable
contact actuated by an exterior force by means of friction wheels which are put into
gear by a magnetic relay, this being controlled by a determining apparatus by means
of movable contacts connected mechanically to the two movements.

page_text: "
3. An automatic current regulator composed of a rheostat of which the movable
contact lever is operated by an electric motor combined with a current inverter and
the movements of which are determined by an apparatus in relation with the current
to be regulated and are exactly proportional to those of the determining apparatus.
4. The application to. automatic current regulators of the principle of displacement.
of.determining contacts so that they follow every movement made by the determining
apparatus.
5. An automatic current regulator substantially as described and represented by
'the annexed drawings: