Improvements in Alternating Current Electro-magnetic Motors and Methods of Operating the same, applicable also to Alternating Current Circuits generally.
Year: 1892

page_text: Date of Application, 20th Apr., 1892-Accepted, 9th July, 1892
DEPORTIVATION.
[Communicated from abroad by WILLIAM STANLEY, Junior, and JOHN FOREST
KELLY, both of Pittsfield, County of Berkshire, and State of Massachusetts,
United States of America, Electricians.]
Improvements in Alternating Current Electro-magnetic Motors and
Methods of Operating the same, applicable also to Alternating
Current Circuits generally.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 :-
Primarily, the invention consists in the combination with an alternating current
motor, of a series of conducting plates arranged in couples and immersed in an
electrolyte by which they are not chemically attacked, and included in the circuit
of the field or armature or both, the number and size of the plates being adjusted
with reference to the current which is passed through them so as to serve as a
polarizing cell, which without decomposition of the electrolyte, will overcome or
neutralize the electromotive force of the self-induction in the circuit in which it is
included.
The invention however, is not only applicable in various ways and for various
specific purposes to alternating current motors, according to the character of the
said motors, but it is also applicable to alternating current circuits or systems in
which a storing up and giving back of a part of the energy or electro-motive force
without material loss is attended with useful results.
The invention is applicable to motors of various forms, both those provided with
commutators and those having independent energizing circuits. For purposes of
this case the former may be regarded as of two kinds; those in which the field
and armature circuits are in series, and those in which these circuits are in
derivation.
In the case of series motors, the purpose of the invention is to neutralize the
retardation of self-induction so as to render available the whole of the electro-motive
force applied to the operation of the motor, for it is well understood that when a
portion of the potential or electro-motive force is taken up in storing energy which,
on the fall of the applied electromotive force, gives back into the generator, this
work while not resulting in an actual loss of power is wasted, so far as its useful
effect on the motor is concerned. The fact, moreover, that the current phase under
such circumstances does not coincide with the impressed electro-motive force,
involves a commercial loss, for the reason that a greater current value for a given
work is required, and this necessitates the construction and use of a plant of greater
capacity than would otherwise be required.
In such cases, therefore, we insert in the circuit in series with the motor or motors,
a polarization cell which will have an electro-motive force equal in value to that of
the self-induction.
When the field of, a motor is in derivation to the main or armature circuit the
retardation therein, owing to the greater self-induction, causes a difference in phase
between the currents in the two motor circuits which is attended with a similar
waste, hence in this case we connect up a polarization cell in the field circuit
sufficient to neutralize the electro-motive force of its self-induction, and a smaller
cell may also be included in the armature circuit for the same purpose, if so
desired.
It is well-known that if two conducting plates be immersed in an electrolyte by
which they are not chemically attacked, and a current passed from one to the other

page_text: through the electrolyte, an electro-motive force due to polarization is set up, which
is manifested on the fall of the potential which produced it. This electro-motive
force is in proportion to the current, other things being equal, and any desired
effect may be secured by a proper proportioning of the size of the plates and the
number connected in series.
In applying our invention, in any given case, we first ascertain the maximum
electro-motive force of self-induction and then construct the polarization cell so that
These
its electro-motive force will be of the same value for the same current.
results are attained in accordance with well-known laws.
It will be observed that the maximum electro-motive force which the polarization
cell should ever be called upon to yield should have a value safely below that which
would produce the breaking down of the electrolyte or in other words, the point at
which electrolysis begins. Furthermore, since the resistance of the cell is not a
function but a mere incident, it should be reduced as far as possible in order to
increase the efficiency of the system.
The theoretical operation of the invention applied in the manner above stated is
as follows: In an alternating current circuit possessing self-induction and containing
a polarization cell, the electro-motive force of self-induction is 90° behind the
current while that of polarization is 90° ahead of the current, so that the two
counter electro-motive forces being at 180° from one another neutralize and the
whole current is rendered available. Under proper conditions the current corre-
sponds with the impressed electro-motive force and the circuit follows, practically,
Ohm's law since there is no opposition to the current except that of inert
resistance.
Certain electrical devices, particularly motors, require for their operation alter-
nating currents differing in phase which are caused to flow through separate or
independent energizing circuits, and it is frequently desirable to obtain these
currents from a single source, as in the case of isolated motors operated by
transformers connected with a main circuit from a more or less distant source.
Our invention also applies to such motors and constitutes a new and improved
means of obtaining this difference of phase between two or more alternating
currents in general, but more particularly such as are derived from a single source
such as the secondary of a transformer. While in principle and without material
change the invention is applicable to those cases where three or more currents are
employed we deem it sufficient, for purposes of this case to describe the invention
as applied to the operation of two circuit motors which require for their most
efficient operation two currents which differ by a quarter phase. From this, and
from the description of one type only of such motors the general nature and
applicability of the invention will be understood.
If in a circuit of alternating currents a polarization cell such as we have described
be included, the electro-motive force of polarization will be greater the greater the
number of couples or pairs in series, and the higher this electro-motive force the
greater will be the negative lag of the current. In other words, the phases of
the current will be ahead of the impressed electro-motive force in proportion to the
excess of electro-motive force of polarization over that of the self-induction which
is practically always present.
On the other hand, the higher the electro-motive force of self-induction in a given
circuit the greater the positive lag of current, or in other words, the farther the
phase of current will be behind the impressed electro-motive force.
We utilize these effects in an efficient and economical manner in any case where
it is desired to obtain between two alternating currents a given difference of
phase, and, as will more fully hereinafter appear, we may do this in a variety of
ways:
In the accompanying drawings the invention is illustrated mainly by diagram.
Figure 1 is a diagram of a series motor to which the invention is applied.
Figure 2 is a similar diagram of a shunt wound motor.
-hat awe known as two-circuit motors

page_text: which are characterized by independent energizing circuits through which are
passed alternating currents differing in phase.
Figure 7 is a view of a modification of the invention.
Figure 8 is a perspective view of the polarization cell.
This latter may be made in many ways, but we prefer to construct a cell or
box A with a number of insulated compartments formed by partitions B. In the
end compartments are plates C, D, connected with the terminals, and other plates E
bent upon themselves are hung or supported over the partitions B. The plates
may be of carbon in acidulated water, or of sheet iron in a solution of caustic
potash or of other proper materials, and are disposed, as shown, in series.
In Figure 1 let G designate a generator of alternating currents and H a circuit
containing the working devices and possessing self-induction. In this figure the
working device is represented as a series motor of which L designates the field
and M the armature. If in such a circuit a polarization cell N be introduced it.
will, if properly adjusted or proportioned with reference to the conditions of the
circuit or current to be employed and in accordance with the considerations
advanced above, so neutralize the effects of the self-induction as to allow the entire
electro-motive force of the generator to be availed of in driving the motor.
So, in Figure 2, where the field L and armature M are in derivation, the effects
of self-induction in both motor circuits may be neutralized by properly proportioned
polarization cells N, N', placed in the two circuits respectively.
The same general result may be secured by employing a polarization cell with
a motor or with each of a number of motors, but in shunt thereto and not in series.
The operation of such a disposition we explain in the following manner :-
The lagging or retarded current may be regarded as made up of two components,
one coinciding in phase with the impressed electro-motive force, the other at right
angles thereto. The current which flows through a polarization cell has a negative
lag with respect to the impressed electro-motive force, that is to say, the electro-
motive force of the polarization cell is ahead of the current, while the opposite is
true of the electro-motive force of self-induction which is behind the current.
If the resistance in series with the polarization cell be very low, the change of
phase will be approximately ninety degrees.
If, therefore, we place in shunt around the motor a polarization cell of very low
resistance and of such capacity that the current driven through it by the impressed
electro-motive force shall be equal in magnitude to the lagging component of the
motor current, the two being 180° apart will completely neutralize each other with
reference to the line and the generator, and the out-put demanded from the one and
the loss in the other will be reduced to proportionality to the work to be
performed, as in a continuous current motor.
This disposition is shown in Figure 7 in which are shown two motors in parallel
with the generator G. Each motor is shown as consisting of an armature M and
field L. In shunts S' to each motor is a polarization cell N of a value adjusted to
neutralize the self-induction of the motor.
A variable resistance R is placed in each branch circuit for adjusting the current
on the start.
In Figures 3 to 6 the application of the polarization cell to two-circuit motors
for producing the necessary difference of phase is illustrated.
L, L' in these figures designate the energizing circuits of a motor of this
character to which current is to be supplied from the secondary S of a transformer,
of which P is the primary.
In one of the circuits or branches from the secondary including one of the
energizing coils as L, a polarization cell N is included which has an electro-motive
force sufficiently high to impart a negative lag of 45° to the current passing in the
circuit.
In the other circuit, or that containing the coil L', a self-induction H is included
that produces a positive lag of 45°, so that the total difference of phase between
the two currents will be 90°.
•

page_text: It has heretofore been proposed to accomplish a like result by the use of
condensers and self-induction, but the employment of polarization cells is much
more efficient and economical, mainly on account of their cheapness; their immense
capacity in small compass, and the slight probability of their being injured by the
current.
Inasmuch as the object sought is to obtain between the two currents a given
difference in phase, the specific arrangement described may be varied. For
example, in Figure 4 sufficient capacity is included in the circuit of coil L to produce
a negative lag of say 60°, while the self-induction of the other circuit is sufficient
only to produce a positive lag of 30°.
If the polarization cell in one circuit and the self-induction in the other are so
adjusted as to balance or in other words, so that the positive and negative lag will
counter-balance, then the current in the main conductor from the source will
coincide with the impressed electro-motive force since it will be opposed by a dead
resistance only. But such conditions would rarely obtain in practice so that a lag
in the main circuit may usually be expected.
To overcome this, and therefore to utilise the entire out-put of the generator in
the operation of the motor, we introduce in the main circuit a polarization cell T,
the electro-motive force of which will neutralize that of the self-induction
producing the lag. (See Figure 5.)
It is obvious that no special appliance for producing self-induction need be used
if the circuit itself have a sufficiently high self-induction, and it also follows that
since both circuits possess more or less self-induction under all circumstances, that
the balance between the positive and negative lag may be secured by inserting
polarization cells of proper capacity in both circuits. (See Figure 4, where one of
the cells N" is indicated in dotted lines.)
In the practical application of the invention the compensation for lag by the
means above described should be made for full load, as it may not be made for
variable loads owing to the reaction of the armature which is greatest. when the
full load is on.
In Figure 6 is illustrated another modification of the invention. G in this figure
represents the generator. The main circuit includes the primary P of a
transformer and one of the coils, as L, of the motor.
The secondary coil S is in circuit with the other coil L'.
If there were no polarization cell in the secondary the lag of the secondary
current behind the primary current would approximate to 180°, but if a polarization
cell N be included in the secondary circuit and constructed so that its electro-
motive force equals that of the self-induction in the secondary, the lag will be so
reduced as to be only 90° behind the primary.
In general the effect of the polarization cell is the opposite to that of self-
induction, and in the case of any two circuits of the kind described it may be
employed in either or both, according to the special conditions which exist, to
produce between the two circuits a given difference of phase.
We do not wish to be understood as claiming the discovery that the electro-
motive force of self-induction is opposed by that of polarization, but our invention
resides in the adaptation of this principle to a useful and practicable purpose, and
in the utilization and application in the manner herein set forth, of a device which
combines enormous capacity in small compass, and by means of which results are
or may be secured that would not be practicable or perhaps possible by the
use of other devices, such as condensers, which have heretofore been proposed.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed as communicated to me by my
foreign correspondent, I declare that what I claim is
an
First. The combination with an electric circuit possessing self-induction, of a
source of alternating currents, conducting plates arranged in couples in
electrolyte and connected in series with the circuit and adapted by adjustment

page_text: to the electrical conditions of the circuit to neutralize by polarization the electro-
motive force of the self-induction in the circuit, as set forth.
Second. The combination with an alternating current motor and in series
with the circuit or circuits of the same, of a polarization cell adapted to yield
an electro-motive force opposite to that of the self-induction of the motor, as set
forth.
Third. The combination with an alternating current motor and in series with or
in shunt to the same, of a series of couples of conducting plates immersed in an
electrolyte which does not chemically attack said plates, and adapted or pro-
portioned to act as a polarization cell for neutralizing the electro-motive force of
the self-induction of the motor.
Fourth. The combination with an alternating current motor having independent
energizing circuits, of a polarization cell included in one circuit and a self-
induction device in the other, as set forth.
Fifth. The combination with an alternating current motor having independent
energizing circuits, of a polarization cell included in one circuit adapted by its
electro-motive force to advance the phase of the current in its circuit with respect
to that of the current in the other circuit, as set forth.
Sixth. In an alternating current motor having energizing circuits adapted by
predetermined relations of self-induction and capacity to produce a difference in
phase between the currents therein, the combination with one or both circuits as
the means for neutralizing the lag of self-induction, of conducting plates
immersed in an electrolyte and connected in series in the same, as herein set
forth.
Seventh. The combination with a main circuit and branches from the same of
different self-induction and capacity, whereby a difference in phase will be
produced in the currents passing therein, of a polarization cell included in the
main circuit and adjusted or adapted to neutralize the resultant lag of the two-
branch circuits.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.