Improvements in Multiple-blade Starting-switches.
Year: 1899

page_text: 5th Dec., 1899-Accepted,
M
on
5th Dec., 1899-Accepto
COMPLETE SPECIFICATION.
mmunicated from abroad by CROCKER WHEELER COMPANY, Manufacturers, a
Corporation organized under the laws of the State of New Jersey, United
States of America, and having its principal place of business at No. 39,
Cortlandt Street, New York City, State of New York, United States of
America.]
Improvements in Multiple-blade Starting-switches.
I, WALLACE FAIRWEATHER, C.E., of 62, Saint Vincent Street, in the City of
Glasgow, Chartered Patent Agent, do hereby declare the nature of this invention
nd in what manner the same is to be performed, as communicated to me
to be particularly described and ascertained in and by the following statement:-
The principal feature of this invention is in the use in connection with a
rheostat in an electrical circuit of a number of independently hand operated
resistance-controlling knife switches which are closed to make contact with the
series of resistances of the rheostat, together with an interlocking device for
preventing the closure of the resistance controlling switches in other than the
It is thus
proper order to effect a graded increase in the current. By the employment of
independently operated switches which must be successively grasped by the hand
and closed, a sufficient time is given to the motor to speed up and check the excess
of current which would flow were resistance cut out too rapidly.
possible to utilize in connection with a rheostat, the best form of contract, namely,
5 a switch-blade and jaws. The contacts are of such a nature as not to be injured
by the sparking attending the breaking of connection, and their number may
be reduced to that required by the electrical conditions attending the starting of
the motor.
The switches may be arranged either in multiple or series relation, and there
20 may be in addition a circuit closing switch which interlocks with the resistance
controlling switches, so that it cannot be brought from open to closed position.
except when the resistance controlling switches are open. The circuit closing
switch may be also an electro-magnetic circuit breaker.
In the accompanying four sheets of drawings, which form a part of thi
25 specification:
Figure 1 is one form of the invention in which the switches are in multip
relation, the switches and interlocking device being mounted on a board ar
shown in perspective, and the electrical connections shown diagrammaticall
Figure 2 shows a modified arrangement of resistances which may be used wi
30 either of the forms of switches herein described.
Figure 3 shows in similar manner to Figure 1 another form of the inventi
in which an automatic circuit breaker and a double-pole main switch are a
mounted on the board and included in the circuit.
Figure 4 is a section on the line -r of Figure 3, the side with the hinges
35 the switch blade being removed, all of the resistances shunting switches be
en and the electro-magnet circuit breaker and double-pole switch being clo
ilar section in which all of the switches are closed.

page_text: Figure 6 is a similar section in which the resistance shunting switches are
closed and the electro-magnetic circuit breaker, and double-pole switch are open.
Figure 7 is a section on the line y-y of Figure 3, showing the electro-magnetic
circuit breaker:
>
Figure 8 shows in similar manner to Figure 1 another form of the invention
in which the resistance controlling switches are in series.
In the form, shown in Figure 11, a series of resistance-controlling switches 1,
2, 3, 4, 5 are mounted on a suitable base B. These switches are connected on the
hinge sides 6 to one of the leads L and on the jaw sides 7 to points along the
sections 8, 9, 10 and 11 of the resistances. The hinges are on a common base,
so as to conveniently make the connection to the lead. When the switch 1 is
closed, the circuit is from the first lead through all the sections of resistance,
to the field F and armature A of the motor to be regulated to the other lead.
When the switch 2 is closed the circuit is around the section 8 but through the
other sections 9, 10 and 11. The closure of the switch 3 cuts out sections 8
and 9. The closure of switch 4 cuts out sections 8, 9 and 10. The closure of
switch 5 cut out all of the sections and connects the lead to the motor without
external resistance. The sections of resistance which are thus successively cut
out vary in value logarithmetically, each bearing substantially the same ratio
to the remaining resistance in the circuit, so that the surge of current on the
successive closure of the switches will be evenly divided between them. To effect
this, the switches must be closed in the definite order which has been indicated,
and a locking bar 12 is provided which prevents the closure of the switches in
any other order. The bar lies under the blades of the switches and has a
movement transverse thereto. The bar has a series of notches 13, 14, 15, 16
and 17 which may be brought under the switch blades and in which the blades
lie when the switches are closed. One side of each of the notches is bevelled
with the exception of the notch 17 for the switch 5 which is last closed. Except
when the corresponding notch is under a switch-blade, its closure is prevented by
the bar. When the switches are all open the bar is drawn by the spring 18. to
the left of the position shown until the pin 19 contacts with one of the
standards 20 by which the bar is guided. In this position none of the notches,
with the exception of notch 13, lie under the blades of the switches, and, con-
sequently only the blade 1 of the first switch can be closed. In closing this switch
the blade contacts with the inclined side of the notch in which it enters. This
cams the bar a slight distance to the right and brings the inclined side of notch 14
under switch 2 so that it can next be closed and the bar cammed an additional step
thereby. The closure of each switch, with the exception of the switch to be last
closed, cams the bar an additional step and positions it so as to permit the closure
of the succeeding switch. The switches, after they have all been opened can
only be closed in the definite order determined by the position of the notches on
the bar. They can be opened in any order. When the switches are all closed
the current flows only through the last switch and the other switches may be
opened without disturbing the connection of the motor to the leads. If this is
done the connection will be so left that the current may be cut off suddenly by
opening only a single switch. In practice from four to seven switches may be
employed, although five are shown.
The, switches herein described are also applicable with resistances arranged in
other ways, as for example in the manner shown in Figure 2, in which switches
are successively, closed to resistances of decreasing value disposed in multiple
instead of around resistances in series.
In the form shown in Figures 3 to 7 the resistance-controlling switches close
to the series of resistances of the rheostat as before, but there is in addition
in series in the circuit a switch 21 which is locked against closure when any of
the resistance-controlling switches are closed, and a double-pole switch. S which
is not mechanically connected with the other switches, by which the connection to
both leads can be made and broken. These switches are in series with each

page_text: er and respecting the circuit in series with the resistance-
ough the latter are in multiple-relation to each other. It follows, there-
e, that no current can pass through the motor armature, unless both the
tch 21, the double-pole switch S and one of the resistance-controlling switches
closed. The switch 21, as shown is held closed by a differentially wound
gnet 22 and is an automatic circuit-breaker which is thrown open by the
ring pressed plunger 23 when the magnetism ceases in the magnet as is the
se whenever either the current exceeds a certain amount, or the potential falls
The main circuit is from one of the leads, through
low a certain amount.
e side of the double pole switch wire 24 a few turns on the differentially wound
agnet, wire 25, the jaw side of the circuit-breaker switch 21 through this switch,
A branch circuit
e or more of the resistance-controlling switches, the armature A of the motor,
e other side of the double pole switch to the other lead L'.
com the main circuit, after passing through the circuit-breaker switch 21 is
hrough the wire 26, a fine winding on the differentially wound magnet of the
ircuit breaker, wire 27, the field F of the motor, through the double pole switch
o the lead L. No current can pass through either winding of the circuit-
breaker magnet, unless the double pole switch is closed. It must, therefore, be
irst closed, then upon closing the circuit-breaker, switch current will flow through
the fine winding, the armature 28 attached to the switch-blade will be attracted,
the switch will be held closed and current will then flow through the field of the
motor. Closure of the resistance-controlling switches may now be made in proper
order to admit current to the armature as described in connection with Figure 1.
The current through the armature also passes through the few turns of the
differential magnet in a contrary direction to the current in the fine winding,
and counteracts the magnetising effect of the fine winding, but not sufficient to
reduce the magnetism and release the switch-blade, unless the flow of current
becomes excessive. Projecting from the locking-bar is a spring-controlled latch 29.
This latch prevents the closure of the circuit-breaker switch if the bar has been
displaced by the closure of any of the resistance-controlling switches, as shown
in Figure 6. If none of the resistance controlling switches are closed, and the
bar is at its extreme position to the left, the circuit-breaker switch can be
closed past the end of the latch as shown in Figure 4. If after the circuit-
breaker switch is closed the resistance-controlling switches are closed, the locking
5 bar will be cammed to the right and the latch will contact with the side of the
blade of the circuit-breaker switch, and be pushed back against its spring, as
shown in Figure 5. If while in this position, the circuit breaker opens from any
cause, as from the cutting off of current by opening the double pole switch, the
latch will be thrown out underneath by its spring as shown in Figure 6, and
40 the circuit-breaker cannot again be closed until the resistance controlling switches
have been opened.
On the form shown in Figure 8 the resistance-controlling switches are placed
in series instead of in multiple, but they are manipulated in the same way
and their closure in other than a definite way is prevented by the locking ba
45 as before.
Having now particularly described and ascertained the nature of my sai
invention, and in what manner the same is to be performed, I declare that wha
I claim is
1. A rheostat provided with a set of independently operated switches, ar
50 means for preventing closure of contact at the switches, except in definite orde
substantially as described.
2. A rheostat comprising a set of switches, a bar to prevent the closure
contact at the switches, and notches in the bar shaped and positioned to preve
closure of contact at the switches, except in definite order, substantially
55 described.
3. A rheostat comprising a set of switches, a bar to prevent closure of cont

page_text: at the switches, notches in the bar shaped and positioned to prevent closure of
contact at the switches, except in definite order, an electro-magnetic circuit-
breaker, and a latch on the bar to prevent closure of contact at the electro-
magnetic circuit-breaker, except when all rheostat contacts are open, substan-
tially as described.
Dated this 4th day of December 1899