A Circuit Breaker for Secondary Currents from Electrical Transformers.
Year: 1890

page_text: Date of Application, 11th Mar., 1890
Complete Specification Left, 1st Dec., 1890-Accepted, 10th Jan., 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by ALFRED MILLS TAYLOR, at present in Baroda, India,
Electrical Engineer.]
A Circuit Breaker for Secondary Currents from Electrical
Transformers.
We SIEMENS BROTHERS & Co. LIMITED of 12 Queen Anne's Gate, Westminster,
in the County of Middlesex, Electrical Engineers, do hereby declare the nuture of this
invention to be as follows:-
In many installations for electric lighting and other purposes to which electricity
is applied, alternating or intermitted currents of high tension are transmitted by
main leads to the primary coils of trasformers, the secondary coils of which supply
electricity of low tension to consumers. This invention relates to circuit breaking
apparatus to be employed at or near such a transformer, which may be at a great
distance from the central station whence the high tension electricity is supplied, this
apparatus being such that, when the high tension supply is cut off at the central
station, the circuit of the secondary coil of the transformer with the leads to consumers
is interrupted. For this purpose, one of the leads from the secondary coil has to pass
on its way through two pairs of contacts, one of each pair being the contact of two
carbons and the other of each pair being a wire dipping in a cup of mercury. The
two wires and the two upper carbons are all fixed to an elastic metal bar which is
attached to the core of a solenoid coil, this core being itself suspended by an adjustable
spring within the solenoid coil which consists of convolutions of one of the main high
tension leads. While the high tension current is maintained, the core is drawn down in
opposition to the spring, bringing the upper carbons in contact with the lower carbons
and then immersing the wires in the mercury, thus closing the circuit of the secondary
coil of the transformer with the consumer's lead. When there is no current in the
high tension lead, the core being no longer drawn down, is raised by the spring, first
drawing the wires out of the mercury while there is still contact of the carbons,
and finally separating the carbons, so that the secondary of the transformer is no
longer in circuit with the consumer's lead. By making the carbon contacts the last
to be separated, sparking at the surface of the mercury is avoided.
Dated this 11th day of March 1890.
.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
A Circuit Breaker for Secondary Currents from Electrical
Transformers.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, Westminster,
in the County of Middlesex, Electrical Engineers, 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 :—
In many installations for electric lighting and other purposes to which electricity is
applied, alternating or intermittent currents of high tension are transmitted by main
leads to the primary coils of transformers, the secondary coils of which supply
electricity of low tension to consumers. This invention relates to circuit breaking
apparatus to be employed at or near such a transformer, which may be at a great
distance from the central station whence the high tension electricity is supplied, this
apparatus being such that, when the high tension supply is cut off at the central

page_text: .
station, the circuit of the secondary coil of the transformer with the leads to consumers
is interrupted.
For this purpose, an automatic circuit breaker is employed, the operation of which
may he explained with reference to the accompanying diagram. One of the leads L
from the secondary coil S has to pass onrits way through two pairs of contacts, one
of each pair UC being the contact of two carbons and the other of each pair M' M²
being a wire dipping in cup of mercury. The two wires and the two upper carbons
are all fixed to an elastic metal bar B which is attached to the core E of a solenoid
coil A this core being itself suspended by an adjustable spring I) within the solenoid
coil which consists of convolutions of one of the main, high tension leads T of which
the primary coil P forms part. While the high tension current is maintained, the
core E is drawn down in opposition to the spring D, bringing the upper carbons in
contact with the lower carbons at C and then immersing the wires in the mercury
at MM, thus closing the circuit of the secondary coil S of the transformer with
the consumers lead L. When there is no current in the high tension lead T, the core E
being no longer drawn down, is raised by the spring D, "first drawing the wires out
of the mercury at M M while there is still contact of the carbons at CC² and
finally separating the carbons, so that the socondary coil S of the transformer is no
longer in circuit with the consumers lead I.
By making the carbon contacts CC the last to be separated, sparking at the
surface of the mercury M' M' is avoided.
Having now particularly described and ascertained the nature--of this inven-
tion and in what manner_the_same is to be performed, we declare that what
we claim is: —
A circuit breaker for secondary currents from electrical transformers consisting
of a set of separable contacts for the secondary lead maintained in opposition to
an adjustable spring by the core of a solenoid excited by the current in the primary
lead, substantially as described.
Dated this 1st day of December 1890.