IMPROVEMENTS IN DYNAMO- ELECTRIC MACHINES
Year: 1879

page_text: LETTERS PATENT to William Elmore, of 91, Blackfriars Road, in the County of
Surrey, Electric Engineer, for the Invention of "IMPROVEMENTS IN DYNAMO-
ELECTRIC MACHINES."
aled the 2nd March 1880, and dated the 4th September 1879.
PROVISIONAL SPECIFICATION left by the said William Elmore at the Office
of the Commissioners of Patents on the 4th September 1879.
WILLIAM ELMORE, of 91, Blackfriars Road, in the County of Surrey, Electric
Engineer. " IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES.
This Invention relates to improvements in the construction of dynamo-electric
machines, the object being by improved arrangement and construction of parts to
obtain a greater extent of the magnetic field of the revolving armature, and so
generate a greater amount of electricity than by apparatus of known construction,
and also to provide means for governing the current, cooling the magnets, and for
instantaneously signalling a reversal of current, and for measuring the current
passing.
In constructing the apparatus end, standards having a broad circular surface
and serving as stationary discs are employed and bolted to a suitable bed plate,
said standards having centrally therein bosses for carrying the central main driving
shaft, and having thereon on the inner surface thereof magnets radially arranged,
as more fully hereafter described, and said shaft carries a pulley or driving piuion
for purpose of transmission on one end thereof, and the other end carries the
commutator, the extremities of the shaft, being supported by bearing standards
fixed to the bed plate.
On the main shaft between the standards is mounted a disc upon. both sides
of which are bolted radial magnets of number and size required, according to the
area of the disc, said disc when so fittted constituting a revolving armature.
•
The magnets of the stationary discs and the revolving armature are constructed
as follows: Two soft iron plates of sector form are connected by a solid or hollow
connecting piece of steel or iron, but preferably of steel of corresponding shape to,
but smaller than the plates, one of said plates serving as a flange for bolting the
magnets either to the revolving disc or to the stationary disc, and the other plate
}

page_text: acting as the soft iron surface, which by revolution of the magnets in face of each
other generates the current. The hollow connecting piece of the plates of the
magnets serves as the core upon which wire is wound. In small machines the
hollow connecting piece or core may be solid, and the connecting piece of
the stationary magnets is in all cases longer than that of the revolving disc, so
as to receive a longer coil of wire. The magnets are bolted in a circle on to and
around the relolving and stationary discs relatively opposite to each other, so that
the revolving disc will carry and be furnished with a circle of magnets upon each
face thereof, so as to revolve in face. of corresponding sets of magnets on the inner
faces of the stationary discs of the standards.
The centre of the revolving disc is fitted with a bush in which are holes lined
with insulating material, through which are passed the wires of the coils of the
magnets, said wires being carried along the shaft to the commutator through a bush
on the shaft passing through and working in the boss of the standard, said wires
being insulated by passing them through small tubes of insulated material.
The magnets are to be wound with wire varying in thickness according to the
" intensity
<<
ог quantity" of the current required, that is, according to the
purpose for which the machine is to be used; thus, if the machine is to be employed
for producing current for electric lighting, then the magnets will be wound with
fine wire to produce "intensity," but if the machine is to be used for, say, electro-
deposition of metals, thick wire will be used to produce." quantity."
In order to prevent the current from changing, and so in the case of plating to
prevent the work in the bath from damage I have devised a governor, which for
convenience I place at the driving end of the machine and drive the same off the
driving shaft. An armed bracket is bolted to the bed-plate and insulated there-
from, and in bosses of said bracket are mounted short shafts carrying mitre wheels,
one of said shafts carrying a transmission pulley to be driven from the main shaft
of the machine to communicate motion to the mitre wheels, and the other rod
passes up through a cylindrical pillar and supports governor balls which are pivoted
on snugs on the upper end of the said pillar; the ends of the arms of the governor
carry hooks or catches which are so arranged as to act upon a central rod passing
through the upper mitre wheel shaft, and upon which central rod within the
cylindrical pillar is arranged a spring, and a screw cap is fitted to the upper end
of the rod so as to adjust the tension of the spring when desired. On the lower
end of the central rod of the governor is mounted a saddle shaped or double armed
piston, which will, according as the speed of the driving wheel increases, and by
action of the catches on the arms of the governor balls be depressed. The
extremities of the double arms of the said piston are platinized and extend into
two cups screwed upon the bed plate and insulated therefrom, and filled with
mercury to such height that the arms of the saddle shaped piston will only dip into
the mercury when the required speed of the machine is attained, and by the
centrifugal force of the governor balls the catches of the arms thereof act to depress
the plunger.
Secured upon the bed plate in front of the machine are the two terminals.
The wires from the magnet coils of the revolving armature are carried as before
described to the commutator, and the current from them is received by the copper
brushes.resting upon said commutator, said brushes being supported by brush holder
standards provided with binding screws, springs being provided to act from above
on the one side, and below on the other to hold the brushes evenly against the
commutator. One of the brushes is connected by insulated cable to one of the
terminals of the machine, and the current from the other brush is carried by cable,
and connected with the wires from all the magnets of the stationary discs, and
thence on to the other terminal, but it is intercepted on its way by the governor as
follows, that is, the cable is divided, and one end is connected to the bottom of one
of the mercury cups, and the other to the second mercury cup, thus leaving a break
between them, and in the circuit when the machine is not working, or when the
speed is not sufficiently high to work the machine properly, contact will-only be
' :

page_text: made by the saddle shaped plunger upon the machine attaining the required speed;
and so depressing and immersing the extremities of the said plunger arms one into
each cup of mercury. The mercury in the cup is covered with glycerine, and the
ends of the plunger arms which dip into the mercury are platinized to prevent
oxidation and ensure instantaneous and perfect contact.
For the purposes of electro-deposition of metals, it is desirable in order to
regulate the amount of current passing into the baths from the main circuit to
introduce a resistance coil in the circuit at the end of each bath in the plating
room, and further, it is desirable to know and to have indicated the exact amount
of current actually passing. Now to effect this I employ the wire which connects
the resistance board with the plating bath as follows, that is to say I give the
'said wire several turns, more or less, around a soft iron core arranged perpen-
dicularly on a stand, and the wire where these turns are made is to be insulated or
covered with cotton, silk, or any other insulating material to make of the soft
iron core an electro-magnet. Above this magnet is arranged an armature at
the end of a lever mounted on a knife edge, the opposite arm of which lever is
graduated to a scale and fitted with a weight as a steel yard. This electro-
magnet will exert an attractive power upon the balanced armature, increasing or
diminishing with the strength of the current passing to the bath, and the scale of
the steel yard will be graduated to indicate the known amount of current generated
or represented by any number of cells of known capacity (say Smee or Bunsen
cells of 3 gallons each), and each graduation will also indicate the zinc surface
which would be required in an ordinary battery to produce. the current.
Now when the baths are at work the strength of the current passing may be
readily ascertained by adjusting the weight upon the scale of the armature lever,
until the weight overcomes the attractive power exerted by the electro-magnet
upon the armature, and so to speak weighing the strength of the current, and the
current passing will be regulated by putting in or taking out so much resistance as
is required, and that by adjusting the handle or contact piece of the resistance coil.
I may duplicate the electro-magnet and increase the contact surface of the
armature when this indicator is used with large machines, or large currents are
being dealt with.
The reversal of current in dynamo-electric machines used for the electro
deposition of metal has heretofore caused considerable loss and difficulty to those
employing the same, I have therefore devised a detector, alarum, and indicator
device which I employ and construct as follows:-I connect the said device on
short circuit between the main and operative cables of the machine under the
bed plate, and independant of the governor. This short circuit wire which should
be fine, say 20 to 40 gauge, according to size of machine, and well insulated is
wound around each of two soft wire cores, and so as to connect them and give
a continuous wire from cable to cable of the machine, which cores are placed end
to end but some distance apart to form electro-magnets, which are placed so that
their opposite poles face each other and are bridged or coupled by the continuous
wire. Between the space between the electro-magnets and at right angles thereto
is fitted a pivoted armature acted upon by a spring to keep same in an inter-
mediate position. Now when the machine is working and the current is passing,
this pivoted armature will be attracted to one of these electro-magnets between
which it stands, and so long as the current continues to pass in the same direction,
the position of the armature will remain unaltered, but should a reversal of the
main current occur, the poles of the electro-magnets will also be reversed, the
armature be repelled from its original position, and be attracted by the opposite
electro-magnet. The armature will in its movement act upon a lever to actuate
a centrally pivoted and insulated index needle, which also acts as a contact maker,
and vibrates between two stops to and from which wires are attached and carried
to a bell, a Léclanché or other battery being interposed in circuit between said
stops.

page_text: "
-Upon the current reversing the armature is repelled as before stated: The
pivoted needle is vibrated to make contact between the two stops which completes
the circuit between the bell and the Léclanché. or. other battery, and the bell will.
continue to ring until stopped by the operator or the the machine is righted.
,
The commutator is constructed substantially as ordinarily; and the ends of the
wires from the magnets on the revolving armature as before described are brought
out through the bush of the stationary disc; but by preference I make the
commutator in sections insulated from each other by any insulating, material, and
each wire is connected with a separate section of the commutator:
In order to keep the hollow magnets cool the stationary disc is perforated at the
back of the magnets, and I employ a blast or current of air from a fan; which air
may be previously refrigerated and direct the current by tubes into the hollows of
'the magnets, suitable outlets being also provided for circulation.

page_text: of wire; in Fig. 3 the cores of the magnets D are shown hollow.
The magnets
bolted in a circle on to and around the revolving and stationary discs F and A
respectively, relatively opposite to each other, so that the revolving disc will carry
and be furnished with a circle of magnets upon each face thereof, so as to revolve
in face of corresponding sets of magnets on the stationary discs A of the
standards.
The centre of the revolving disc is fitted with a bush H in which are holes lined
with insulating material through which are passed the wires of the coils of the
magnets G, said wires being carried along the shaft to the commutator E through a
perforated bushing H on the shaft C, and passing through and working in the boss
of the standard A, said wires being insulated by passing them through small
tubes of insulating material, as will be clearly understood upon reference to Figs. 3
and 5.
The magnets are to be wound with wire varying in thickness according to the
"intensity" or "quantity" of the current required, that is, according to the purpose
for which the machine is to be used; thus if the machine is to be employed for
producing current for electric lighting then the magnets will be wound with fine
wire to produce "intensity," but if the machine is to be used for, say, electro-
deposition of metals thick wire will be used to produce "quantity." The wires
upon the opposite stationary magnets are wound and connected, as is well under-
stood, in such manner as to give opposite polarity to each.magnet facing the other,
and so forming pairs between which the armature.revolves.
In order to prevent the current from changing or reversing, and so in the case of
plating to prevent the work in the bath from damage I have devised a governor
which for convenience I place at the driving end or back of the machine and drive
the same off the driving shaft. An armed bracket I is bolted to the bed plate and
insulated therefrom, and in bosses of said bracket are mounted short shafts carrying
mitre wheels K, one of said shafts carrying a transmission pulley L to be driven
from the pulley L' of the main shaft C to communicate motion to the mitre wheels
K, and the other rod of the mitre wheel passes up through a cylindrical pillar M,
and supports governor balls which are pivoted on snugs N on the upper end of the
said pillar M; the ends of the arms of the governor carry hooks or catches d
which are so arranged as to act upon a central rod e passing through the upper
mitre wheel shaft, and upon which central rod within a boxing fin. the cylindrical
pillar M is arranged a spiral spring, and a screw cap g is fitted to the upper end
of the rod e so as to adjust the tension of the spring when desired. On the lower
end of the central rod c of the governor is mounted a saddle shaped or double
armed piston O, which will, according as the speed of the driving wheel.increases
and by action of the catches & on the arms of the governor balls, be depressed. The
extremities of the doublefarms of the said piston O are platinized and extend into
two cups P screwed upon the bed plate and insulated therefrom, and filled with
mercury to such height that the arms of the saddle shaped piston O will only dip
into the mercury when the required speed of the machine is attained or exceeded,
and by the centrifugal tendency of the governor balls the catches of the arms thereof
do act to depress the plunger.
Secured upon the bed plate of the machine and insulated therefrom are the two-
terininals placed as shown in Figs. 1 and 2, or in other convenient position.
The wires from the magnet coils G of the revolving armature F are carried, as
before described, to the commutator E, and the current from them is received by
the copper brushes resting upon said commutator, said brushes (indicated by dotted
lines in Fig. 2), the same being supported by brush holder standards E' provided
with binding screws, springs (not shown) being provided to act from above on the
one side and below on the other to hold the brushes evenly against the commu-
tator. One of the brushes is connected by insulated cable directly to one of the
terminals of the machine, and the other brush is connected with all the "inside"
wires from all the magnets D of the stationary discs.A, all the outside wires of the
stationary. magnets D being connected up with the other terminal Q. When, how-

page_text: ever, the governor is employed the outside wires are intercepted thereby, that is,
the wires are carried to one of the mercury cups P, and the other mercury cup is
connected with the second terminal of the machine, thus leaving a break between
the cups and in the circuit when the machine is not working, or when the speed is
not sufficiently high to work the machine properly. Contact will only be made
by the saddle shaped plunger O upon the machine attaining the required speed,
and so depressing and immersing the extremities of the said plunger arms one into
each cup P of mercury. The mercury in the cup is covered with glycorine, and
the ends of the plunger arms O which dip into the mercury are platinized to
prevent oxidation and ensure instantaneous and perfect contact. A flexible cover
of thin rubber cloth, for instance, which is secured by a ring piece P¹ is provided
to keep out dust and dirt from the cups P.
The use of the governor in dynamo-electric machines being to break contact
when the number of revolutions of the armature are less than the speed required for
the proper working of the machine it is important that this function should be
properly performed, but this is not always the case. With revolving cup of
mercury, as in Weston's machine, even when the speed is very low the mercury is
thrown up in a spiral column from the centre, thereby making contact with the
disc above, and thus the current is allowed to pass improperly, and in this way the
utility of the governor is destroyed. Again, when the armature. revolves at too
high a speed the mercury in the revolving cup is thrown upward with great violence
against the contact, disc, and becomes scattered in more or less minute particles all
over the machine and the surrounding floor; and if the machine is situated near
the depositing bath the mercury not unfrequently finds its way into that vessel.
In a gilding or plating room the diffusion of myriads of mercury globules would
do incalculable mischief if coming in contact with the work. Independent of the
loss of mercury thus sustained and the consequent irregularity of the working of
the machine by its absence the spreading of mercury all round and about the
vicinity of the machine would do much harm.
Another defect in the rovolving cup is that the stationary pin to which the
contact disc is attached frequently becomes loosened by the vibration of the
machine, causing it to slip down and make permanent contact with the mercury or
with the mercury cup itself, whereby the governor ceases to act and the work.in
the bath is likely to be impaired or spoiled. Another point of importance is that
the rapid motion of the mercury within the cup and the constant friction to which
it is subject, when the machine is in motion, causes the mercury to become oxidized
even when glycerine is employed to prevent it. It is not an uncommon circum-
stance to find as much as a desert spoonfull of oxide and mercury in a finely
divided state in the cup after it has been freely used, and it is needless to say that
this would tend geatly to diminish the effective action of the governor.
The advantages of the new governor will be obvious as all the above enumerated
defects are, by its use, avoided.
For the purpose of electro deposition of metals, it is desirable in order to regulate
the amount of current passing into the baths from the main circuit, to introduce
what is known as a resistance coil in the circuit at the end of each bath in the
plating room, and, further, it is desirable to know and to have indicated the exact
amount of current actually passing. Now, to effect this, I employ the wire which
connects the "resistance board" R, and as shown in Fig. 9 with the plating bath S,
as follows, that is to say, I give the said wire several turns, more or less, around a
soft iron core h, arranged perpendicularly on a stand i, and the wire where these
turns are made is to be insulated or covered with cotton, silk, or any other.insulating
inaterial so as to make of the soft iron core an electro-magnet. Above this magnet
is arranged an armature at the end of a lever mounted on a knife-edge support 7,
the opposite arm of which lever is graduated to a scale m, and fitted with a weight
n as a steel yard. This electro-magnet will exert an attrative power upon the.
balanced armature k, increasing or. diminishing with the strength of the current.
passing to the bath, and the scale of the steel yard will be graduated to indicate.

page_text: the known amount of current generated by any number of cells of known capacity
(say "Smee " or "Bunsen" cells of 3 gallons each), and to indicate the weight of
metal deposited per hour under equivalent conditions. Each graduation of the
scale will also indicate the zinc surface which would be required in an ordinary
battery to produce the current. Now, when the baths are at work the strength of
the current passing may be readily ascertained by adjusting the weight n upon the
scale m of the armature lever until the weight overcomes the attractive power
exerted by the electro-magnet h upon the armature k, and, so to say, weighing the
strength of the current. Or I may graduate the arm of the lever in such proportions
that it indicates the weight of copper deposited per hour when using in a depositing
bath anode and cathode of given surface at given distance apart, from which may
be readily obtained the weight of any other metal, the same current would under
équivalent conditions deposit, and the current passing will be regulated by "putting
in" or "taking out" by the resistance board coil, so much resistance as is requiried,
and that by adjusting the handle or contact piece of the "recistance-board" as will
be well understood.
I may duplicate the electro-magnet h, and increase the contact surface of the
amature when this indicator is used with large machines or large currents are
being dealt with.
The reversal of current in dynamo-electric machines used for the electro deposition
of metal has heretofore caused considerable loss and difficulty to those employing
the same. I have therefore devised a detector alarum and indicator devico which I
employ and construct as follows, and as shown in Figs. 10 and 10ª. I connect the
said device in circuit with the machine and bath. This connecting wire will vary
according to the size of the machine, and is to be well insulated and wound around
each of two soft iron cores o, and so as to form part of the continuous wire from the
machine to the bath, which cores o are placed end to end, but some distance apart
to form electro-magnets which are placed so that their opposite poles face each
other, and are bridged or coupled by the continuous wire. Between the space
between the electro-magnets and at right angles thereto is fitted a pivoted polarized
armature p, acted upon by a spring q, to hold same in an intermediate position..
Now, when the machine is working and the current is passing, this pivoted armature
p will be attracted to one of these electro-magnets o, between which it stands, and
so long as the current continues to pass in the same direction the position of the
armature will remain unaltered, but should a reversal of the main current occur the
poles of the electo-magnets will also be reversed, the armature will be repelled from
its original position, and be attracted by the opposite electro-magnet. The
armature P will in its movement actuate a centrally pivoted and insulated index
needle (the pivot p¹ being common to both p and 7) which needle also acts as a
contact maker, and vibrates between two stops 8, s³, to and from which wires are
attached and carried to an electric bell t; a Léclanché or other battery u being
interposed in circuit between said stops. Upon the current reversing, the armature
pis repelled as before stated, the pivoted needle r is vibrated to make contact
between the two stops 8, 8¹, which completes the circuit between the bell t and the
Léchlanché or other battery, and the bell will continue to ring until stopped by the
operator, or the machine is righted.
Instead of employing the separate devices for governing the current for preventing
reversing, for signalling to the operator, and for measuring the strength of current,
as before described, I combine them in one apparatus, as represented in Fig. 11 of
the Drawings, wherein h is a wire coiled core forming an electro-magnet; k,
polarized armature, the support of which armature k is connected up by the main
current cable with the perpendicular coil h, and said armature reposes when the
circuit is closed against a contact stud o immediately above it, and from which
studo the continuation of the main current cable is carried. The repose of the
armature lever against stud o is such that the armature k does not quite touch the
electro-magnet h, and is held there with a force proportional to the strength of
current passing. If now a current in a contrary direction traverses the coil the

page_text: armature is at once repelled and breaks the main current, and the lever arm will
fall by its weight and repose against a stud s¹ (connected up with an alarm bell
circuit) immediately below it, placed there to limit its play; at the same time it
will close the bell circuit by contact with stud s¹ and retain it closed.
The bell circuit is made by the wire from the post supporting the armature,
thence to the battery u, thence to bell tand on to stud s; thus the circuit of the
alarm bell t will only be complete when the armature lever is repelled from the
magnet h on the reversal and consequent breaking of the main current, so that
the bell will continue to ring until the reversal is attended to, and until such time
the bath is out of operation and no spoiling of the articles under treatment can
take place from this cause. On the lever bar of the polarized armature k are
graduations m, used in the same manner as described for and shown by the same
letter of Fig. 9; and it will be obvious that a loop current may be employed
instead of the main current to magnetize the core of the electro-magnet h. One of
the said combined apparatus will be placed between the current passing to each
bath in a plating room.
To ensure the utmost certainty in working, the contact parts of the polarized
armature bar ; m, will be provided with mercury contact arrangement as will be
readily understood and applied by any practical workman.
The commutator is constructed substantially as 'ordinarily, and the ends of the
wires from the magnets on the revolving armature, as before described, are brought
out through the bush of the stationary disc A, but by preference I make the com-
mutator in sections, insulated from each other by any insulating material, and each
wire may in such case be connected with a separate section of the commutator.
In the case of the machine represented in Figs. 8 and 8 the plates a of the
stationary magnets D are made with an enlarged portion a', and the said magnets D
are connected by transverse magnets D₁, and so the power of the stationary magnets
will be increased; also in this Fig. 8 it will be seen that the governing arrange-
ment described in reference to Fig. 11 is shown applied instead of the centrifugal
governor of Figs. 1, 2, and 4, but this is shown here for illustrative purpose. For
electric lighting and telegraphic purposes the machines may be employed without
the governor device.
For machines of large construction, and where larger currents are to be developed,
the number of the armatures F and stationary magnet standards A may be increased.
Thus, for a machine having two of the revolving armatures upon the shaft C there
will be provided three stationary magnet standards A, and so on.
In order to keep the hollow magnets cool the stationary disc is perforated at the
back of the magnets, and I employ a blast or current of air from a fan, which air
may be previously refrigerated, and direct the current by tubes T into the hollows
of the magnets, suitable outlets being also provided for circulation of the air through
the saine.
Having now described the nature and particulars of the said Invention I
claim,―
First. The dynamo-electric machine having armature F (one or more) with
magnets G revolving between standards A fitted with their magnets D, connected
or not by transverse magnets D₁, the whole constructed and arranged substantially
as herein set forth, and shown by Figs. 1, 2, 3, 5, 6, 7, 8, and 8a of the Drawings.
Second. The magnet frames D, G, with their sector shaped plates a and b, con-
nected by the core c, whether hollow or solid, substantially as and for the purpose
herein set forth, and shown in Figs. 1, 2, 3, 5, 6, 7, 8, and S.
Third. In a dynamo-electric machine, as shown in Fig. 8, the sector shaped
magnet plates with the enlarged portion a¹, as and for the purpose herein set forth,
and shown in Figs. 8 and Sa.
Fourth. The use of air, refrigerated or not, for cooling of the stationary magnets D
with hollow cores c and air tubes T, substantially as shown and described in
reference to Figs. 1, 2, 3, and 8.
Fifth. The centrifugal governor for dynamo-electric machines operated from the

page_text: main shaft C.through gearing to revolve the pillar M, and through its connections
to depress the rod e and saddle O to make or break contact of the current through
the mercury cup P, the whole constructed, operating, and connected substantially
as and for the purpose herein set forth, and shown in Figs. 1, 2, and 4.
Sixth.. The indicator-balance, consisting of the electro-magnet h, armature k, with
its balanced and graduated lever bar m and weight n, substantially as and for the
purpose herein specified, and shown in Fig. 9.
Seventh. The reversed current detector and indicator apparatus, consisting of the
electro magnets o, polarized armature p, balance spring q, central pivot p¹, carrying
armature p, and. needle, operating in connection with the contact points 8, 8', of
the electric bell circuit of. battery u, the whole in combination, substantially as
and for the purpose herein set forth, and represented in Figs. 10 and 10a.
Eighth. The combined governor, current reversal preventer, "current balance,"
and alarum apparatus, constructed and operating substantially as and for the purpose
herein described in reference to and represented in Fig. 11 of the Drawings.
Ninth. In dynamo-electric apparatus the breaking of the current automatically
by means of an electro-magnet / with an armature l, and bar m, and contact piece o,
used substantially as and for the purpose herein specified in reference to Fig. 11.
In witness whereof, I, the said William Elmore, have hereunto set my hand
and seal, this Third day of March, in the year of our Lord One thousand
eight hundred and eighty.
In the presence of
WALTER A, BARLOW,
Patent Agent & Engineer,
6, St. Paul's Churchyard,
London, E.C.
WILLIAM ELMORE. (L.S.)