Improvements in Switches for Electric Motors.
Year: 1897

page_text: Date of Application, 29th Oct., 1897
Complete Specification Left, 29th Aug., 1898-Accepted, 1st Oct.,
1898
Improvements in Switches for Electric Motors.
We, HENRY HERBERT TURNER, ALBERT TURNER, and ARNOLD TURNER, all of
Ashton Road, Denton, Lancashire, Engineers, and GEORGE SHAW AVEYARD, Katherine
Street, Ashton-under-Lyne, Electrician, do hereby declare the nature of our said
invention to be as follows
-1
In switches as at present devised it is possible for the current to be turned on too
quickly, thereby causing damage to the armature windings, commutator and
brushes, and a fluctuation of voltage, which is not permissible on public electric
lighting mains.
It is also possible for the current to be switched off in a manner
that causes fluctuations of voltage on the electric lighting mains, and as the switches
having no motion to break the shunt and main circuits quickly, excessive sparking
results, thereby causing the contacts to be burnt away.
"
Our invention therefore has for its object to provide means whereby the "shunt "
current may be turned on slowly, and so magnetise the magnets before the armature
receives its current, also to utilise the same means for gradually cutting out
resistance in the armature circuit, whereby the armature may receive its proper
working voltage by degrees, and so attain its proper speed gradually. Similarly, on
stopping the motor, to gradually add the resistance in suitable amounts in the
armature circuit, whereby the "watts are decreased in suitable quantities until such
times as all the resistance is inserted in the armature circuit, when both the armature
and shunt circuits are broken simultaneously, and the action being a quick one,
"arcing" or burning away of the contacts is prevented. By our improved device
it is practically impossible to switch on the armature circuit until the shunt winding
receives its proper current, and it is practically impossible to break the circuit before
the resistance is gradually added.
In accordance with our invention we employ a long arm or lever, which is
fulcrummed at one end to a nut or contact, mounted upon a finely threaded screw
working in brackets upon the face side of an ordinary switch board. The free
end of this lever forms a latch or hook, and beneath such hooked extremity we
mount the main and shunt switch arms, links and contacts. When in the shut-off
position, the hooked extremity of the lever aforesaid rests on one of the switch arms,
and engages with its extreme edge.
The nut to which said lever is fulcrummed also carries the armature switch or
contact, and directly behind the screw and fixed upon the switchboard are the
several "cut-out" contacts of the resistance coils.
It will now be seen that with the aforesaid screw provided with a winch or
like handle, and by the screw being of a fine pitch, the effect of turning the
screw (in starting the motor) will be to traverse the nut along the screw and thereby
cause it to gradually pull forward the aforesaid hooked lever, which being hooked on
to the main and shunt switch as aforesaid, pulls such switch forward also, and
consequently into contact with the contact plates or terminals of the main and
shunt circuits at an appropriate rate of movement, according to the pitch of
screw.

page_text: With the main shunt thus full on, the further traverse of the nut, by means
of the continued turning of the screw, then serves to bring the nut slowly into
contact with the successive contact plates of the armature circuit, and by the
time the nut has reached, or almost reached, the end of the screw the last
contact-plate is reached, and the, proper working voltage imparted to the motor.
When it is desired to stop the motor.or. shut off current the motion of the screw is
reversed, and consequently as the resistance is increased, until it reaches its maximum
the armature watts are gradually reduced, and as soon as that is effected, the shunt
and armature are then shut off by the point or end of the hooked lever coming in
contact with the main and shunt switch which it pushes forward until clear of the
shunt terminals, when by reason of a set of springs, the switch automatically returns
to its normal position..
In such way it will be observed that whilst we put the shunt and armature current
on slowly, we also slowly reduce the watts in the armature circuit until a certain
point is reached, when we then take off both quickly, which is very desirable for
the proper working of the motor.
The hooked lever when not sustained by the switch rests upon a bracket or stud,
with which, when returning to engage with the main and shunt switch, a slight
double incline or cam on its under edge engages, and causes the lever to rise above
and drop behind the switch for re-starting.
By the same arrangement one or more contacts may be used in the shunt circuit,
so that resistance may be inserted or reduced.
Since both switches are controlled by one handle, we may for the purpose of
preventing the main and shunt switch being operated separately, cover the main and
shunt switch with a (by preference) glass cover, which in case of emergency can. be.
readily broken to gain access to the main and shunt switch, and enable the current
to be switched off immediately.
. Dated this 28th day of October 1907
prevents in Switches for Electric Motors.
We, HENRY HERBERT TURNER, ALBERT TURNER, and ARNOLD TURNER, all of
Ashton Road, Denton, Lancashire, and GEORGE SHAW AVEYARD, Katherine Street,
Ashton-under-Lyne, Electrician, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :—
In switches as at present devised it is possible for the current to be turned on too
quickly, thereby causing damage to the armature windings, commutator and brushes,
and a fluctuation of voltage, which is not permissible on public electric lighting
mains. It is also possible for the current to be switched off in a manner that causes
fluctuations of voltage on the electric lighting mains, and as the switches have no
motion to break the shunt and main circuits quickly, excessive sparking results and
the contacts burn away.
Our invention has for its object to provide means, whereby the "shunt" current
may be turned on slowly, and so magnetise the magnets before the armature receives

page_text: its current, also to utilise the same means for gradually cutting out resistance in the
armature circuit, whereby the armature may receive its proper working voltage by
degrees, and so attain its proper speed gradually. Similarly, on stopping the motor,
to gradually add the resistance in suitable amounts in the armature circuit, whereby
the "watts " are decreased in suitable quantities until such times as all the
resistance is inserted in the armature circuit, when both the armature and "shunt"
circuits are broken simultaneously, and the action being a quick one
burning away of the contacts is prevented. By our improved device it is practically
impossible to switch on the armature circuit until the shunt winding receives its
proper current, and it is practically impossible to break the circuit before the
resistance is gradually added.
arcing" or
And in order that our said invention may be more readily understood and carried
into practical effect we have hereunto annexed a sheet of drawings on which we have
shewn a front view of a switch-board constructed or fitted up in accordance with our
invention, and will now proceed to describe the same with the various letters of
reference marked thereon.
In accordance with our invention, we employ a long arm or lever (A) fulcrummed at
one end (A¹) to a nut or contact, (B) mounted upon a finely threaded screw (C)
working in brackets (D) upon the face side of the ordinary switch-board (E). The free
end (A) of lever (A) forms a latch or hook, and beneath such hooked extremity we
mount the main and shunt switch arms (F), (G), with links (H), (I) and con-
tacts (J), (K), (L). When in the shut-off position, the hooked extremity of the
lever (A) rests on the switch arms (F) and engages with its extreme edge as
illustrated.
The nut (B) to which lever (A) is connected also carries the armature switch or
contact, and directly behind the screw and fixed upon the switchboard are the several
"cut-off" contacts (M) of the resistance coils.
It will readily be seen that with the aforesaid screw provided with a winch or like
handle (N) and the screw being of a fine pitch, the effect of turning the screw (in
starting the motor) will be to traverse the nut (B) along the screw (C) and thereby
cause it to gradually pull forward the aforesaid hooked lever (A) which being hooked
on to the arm (F) as aforesaid, pulls such arm forward also, and consequently into
contact with the contact plates or terminals (J), (K) of the main and shunt circuits
at an appropriate rate of movement.
With the main shunt thus full on, the further traverse of the nut (B) by means of
the continued turning of the screw (C) then serves to bring the nut (B) slowly into
contact with the successive contact plates (M) of the armature circuit, and when the
nut (B) has reached, or almost reached, the end of the screw (as shewn by dotted
lines) the proper working voltage is imparted to the motor.
When it is desired to stop the motor or shut off current the motion of the screw (C)
is reversed, and consequently as the resistance is increased until it reaches its
maximum, the armature "watts ""
are gradually reduced, and as soon as that is
effected, the shunt and armature are then shut off by the point or end (A¹) of the
hooked lever (A) coming in contact with the main and shunt switch which it pushes
forward until clear of the shunt terminals, when by reason of a set of springs (0), (0¹)
the switch arms (F) (G) automatically return to their normal position.
It will be observed that whilst we put the shunt and armature current on slowly,
we also slowly reduce the "watts" in the armature circuit until a certain point is
eached, when we then take off both quickly, which is very desirable for the proper
working of the motor.
The hooked lever (A) when not sustained by the switch rests upon a bracket or
tud (Q) with which, when returning to engage with the main and shunt switch, a
light double incline (R) on its under edge engages, and causes the lever to rise
bove and drop behind the switch for re-starting.
By the same arrangement one or more contacts may be used in the shunt circuits,
o that resistance may be inserted or reduced.

page_text: Since both switches are controlled by one handle, we may for the purpose of
preventing the main and shunt switch being operated separately, cover the main and
shunt switch with a (by preference) glass cover, which in case of emergency can be
readily broken to gain access to the main and shunt switch, and enable the current
to be switched off immediately.
Having thus 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
I. In switches for electric motors, the means substantially as herein set forth for
slowly turning on current to the maguets, and slowly cutting out the resistance to
the arinature circuit, and by a reverse action slowly putting resistance into the
armature circuit and causing the quick turning off of the current to the magnets,
as set forth.
HENRY HERBERT TURNER,
ALBERT TURNER,
ARNOLD TURNER,
GEORGE SHAW AVEYARD,
By John G. Wilson & Co., Agents.