An Improved Electrostatic Switch and Indicator for Alternating Current Circuits.
Year: 1891

page_text: Date of Application, 4th June, 1891-Accented, 11th July, 1391
COMPLETE SPECIFICATION.
An Improved Electrostatic Switch and Indicator for Alternating
Current Circuits.
I, ALFRED UPTON ALCOCK of 206 Russell Street. Melbourne in the Colony of
Victoria, Electrician, 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 :—
This invention relates to an improved switch and indicator for alternating current
circuits which has been designed mainly for the purpose of placing alternating
dynamo machines into parallel circuit and secondarily for the purpose of indicating
when the line currents or machines are in "phase" or synchronism.
I will more particularly describe my invention with reference to the accompanying
drawings in cach of the figures of which similar parts are indicated by similar
letters of reference, and in which
Figure represents a side view, and
Figure 2 a plan of the electrostatic switch and indicator.
Figure 3 is a transverse section through the circuit closing part of the switch.
Figure 4 is a front view and
Figure 5 a side view of a modified form of indicator.
In the form of apparatus represented in Figures 1, 2, and 3, A is a horizontal
base plate constructed of any suitable non-conducting material and having secured
at about its centre, a vertical pillar or support B having on its upper ends the
bearings for the knife edges C₁ of the balance or rocking beam C, the motion of
which may be limited by the adjustable screws B. The support B is connected by
the conductor B2 with the machine which it is desired that the switch shall place in
parallel circuit. The beam C carries at one end by an insulating suspender a
copper aluminium or other suitable link or circuit closer D arranged above two
disconnected mercury cups D' and D, the former being connected with the main
line or circuit D³ and the latter to one pole of or branch from the disconnected
machine this latter connection being controlled by a hand switch.
At the opposite end of the beam C there is carried by suitable conducting
suspenders, an aluminium or other suitable light metallic disc E arranged imme-
diately above another corresponding metallic disc E' mounted upon the base A and
connected to the alternator in circuit by the conductor E; the suspended disc E
being in circuit through the suspenders, beam and pillar or support with the
machine to be placed in circuit by the switch. The actual metallic contact of the
discs is prevented by means of suitable distance pieces E³. F is a plain or graduated
dial attached to the pillar B, and F' is an index finger attached to the beam in
such a manner as to indicate on the dial the position of the beam.
When it is desired to throw the alternating machine controlled by the switch into
parallel circuit with another machine or other machines already supplying the main
circuit, the additional machine is brought up to shew the same difference of
potential as the main circuit and an artificial load is inserted corresponding with
the actual load to be carried. One pole is now switched into the main circuit and
the other pole to the electrostatic switch.
It is well understood that oppositely electrified bodies tend to attract each other,
and that similarly electrified bodies tend to repel each other. The switches having
been closed the discs E E' will at once become electrified, and if the currents are
synchronous or "in phase" the discs will be mutually repelled, whilst if the
currents are insynchronous they will be attracted. From the construction of the
apparatus it will be seen that when the discs E E' are mutually attracted, the disc E
and balance will assume the position shewn by the dotted lines and the circuit

page_text: through the two mercury cups will be open. On the other hand, if the discs are
mutually repelled, the disc and balance will assume the position shewn by the
dotted lines in Figure 1 and the circuit through the two mercury cups will be
closed and consequently the machine the circuit of which is controlled by the
switch will be put into circuit through the mercury cups as soon as synchronism of
the respective currents and the resulting similar electrification of the discs occurs.
Also, if the currents generated by the respective sources should cease to be
synchronous or should not be "in phase "the discs will be attracted and the
circuit D D will be opened thus cutting out the generator controlled by the
switch. The apparatus has been shewn and described as applied to one pole only
of the additional alternate current generator but in practice I prefer to utilise it
for both poles.
Figures 4 and 5 represent a modified form of construction which I adopt when
the apparatus is required only as an indicator of synchronism or insynchronism in
the respective alteration of current in two circuits. In these figures parts similar
to those in the figures hereinbefore described are indicated by similar letters of
reference. G is a pendulum carried by the knife edges C¹ on the bearing bracket B
mounted upon a base A of non-conducting material. E is the metallic disc secured
upon the lower end of the pendulum, and E' is a fixed disc corresponding with the
disc E. Both these discs are curved as shewn in Figure 4 to the radius of the
pendulum. F is a dial fixed upon the base, and F is a pointer or index finger
secured to the pendulum and moving with it over the face of the dial. 12 and
E are conductors corresponding with those similarly indicated in Figures 1 and 2.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
what I claim is,
1. An electrostatic switch constructed arranged and operating substantially as
and for the purpose hereinbefore described and as illustrated by the accompanying
drawings.
2. An electrostatic indicator shewing the synchronism or absence of synchronism
in two alternating electric currents, constructed arranged and operating substan-
tially as herein before described and as illustrated by the accompanying drawings.
3. An electrostatic switch and indicator constructed arranged and operating sub-
stantially as and for the purpose hereinbefore described and as illustrated by the
accompanying drawings.
4. In an electrostatic switch the combination and arrangement of the two discs E
and E' substantially as and for the purpose hereinbefore described and as illustrated
by Figures 1 and 2 of the accompanying drawings.
5. In an electrostatic indicator for two or more alternating currents, the com-
bination and arrangement of the two discs E and E' substantially as and for the
purpose herein before described and as illustrated by the accompanying drawings.
Dated this 3rd day of June A.D. 1891.
WILLIAM E. HEYS,
Agent for the Applicant.