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Патент USA US2123965

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July 19, 1938.
F, X; REES
2,123,965
TRACK CIRCUIT
Filed Aug. 2]., 1935
FIG.1.
~ @1
ATTORN‘EY
Patented July 19, 1938
2,123,965
oFFice
uurrro snares
2,123,965
TRACK CIRCUIT‘
> Frank X. Rees, Albany, N. Y., assignor to General
Railway Signal Company, Rochester, N. Y.
Application August 21, 1936, Serial No. 97,204
3 Claims.
This invention relates to improvements in the
well-known track circuits for railroads, and
more particularly to'alternating current track
circuits.
5'
10
(Cl. 246-34.)
Various characteristic features, attributes, ‘and
advantages of the invention will be in part ap
parent, and in part pointed out, as the descrip
is to improve the shunting operation of the usual
tion progresses.
The accompanying drawing illustrates in a
simpli?ed and diagrammatic 'manner certain
track re'lay .of alternating current track circuits
speci?c embodiments of the invention, the parts
under varying conditions of rail surface and bal
last resistance.
and circuits being shown more with the view of
facilitating an explanation and understanding
of the invention, than for the purpose of showing
in detail the structural organizations to be em
.The primary object .of ‘the presentinvention
This invention is in the nature of a variation
or modi?cation for carrying out the principles
and mode of operation characteristic. of the
track circuit organization disclosed and claimed
in my prior application Ser. No. 24,074, ?led May
15' 29, 1935, and no claim is made herein to the in
vention disclosed in said prior application.
The reliable operation .of the usual track cir
cult depends upon establishing a conducting
path of low resistance through the axles and
wheels of a car or train; and the weight of the
equipment and condition of the rail surface are
important factors affecting theresistance of a
wheel shunt. For ‘example, where the track
rails of ,sidings, crossovers, and the like arein
frequently used, a coating of rust, usually an .iron
oxide, accumulates on the rail surface, and
makes any wheel shunt of high resistance for
the relatively small inter-rail voltages commonly
employed; and even where train movement. is
30, frequent and the rail surface appears clean, .a
coating or ?lm in the form of .an oxide of silicon,
25
or some other stable. compound, is present on the
rail surface, and offers a relatively high effec
tive resistance for low voltages. It is found that
{:5 these various coatings or ?lms on the rail sur
ployed in practice.
In the drawing, Fig. 1 shows one track circuit
section equipped with an alternating current
track circuit in accordance with this invention;
Fig. 2 is a fragmentary View illustrating a modi
?ed arrangement including a single element
relay with the usual impedance bond; and Fig. 3
is an explanatory diagram of a theoretical rela
tion of the primary and secondary ?uxes and 20
secondary voltage. of a peaker voltage trans
former characteristic of the invention.
Referring to Fig. 1, it is assumed that the
track rails l of the track section shown will be
bonded together in the usual way, with insulated.
joints 2 in both track rails to de?ne the ends
of the track section. At one end of the track
section, preferably the entering end, an .alter
nating current track relay T of the .usual type
and construction is connected across the track
rails I. As illustrated, this track relay T is of
the usual two-element or polyphase type, having
a track phase winding 3 connected across the
track rails and a local winding 4 connected to the
usual transformer 5 energized from an alternat 35
face, apparently because they are in the nature
ing current line 6, which in turn is energized
of .a stable chemical compound or composition,
will break down and become a low resistance
from a generator G,‘ or equivalent source, usually
of a commercial frequency, such as 60 cycles.
The track relay '1‘ may be a single element relay
of the vane or rotor type, or in fact a relay of
any one of the various types well known in the
art and used for alternating current track cir
cuits as for instance shown in Fig. 2.
conducting path upon the. application of suffi
<i0= cient voltage, which may be termed an ionization
voltage.
Generally speaking, and Without attempting
to de?ne the exact nature and scope of the in
vention, it is proposed to provide a transformer
of special construction, conveniently termed a
peaker voltage transformer for supplying cur
rent to the ordinary alternating current track
circuit, so» that relatively high peak voltages of
short duration are obtained,'as compared with
5.0‘ the usual sine wave shape of voltage required for
the average ore?ective relay energizing current,
thereby serving to break down or ionize the ?lm
or coating on the rail surface and render more
effective the shunting action of the wheels and
55. axles of a train or trains.
In accordance with this invention, alternating
current is supplied .to the other end of the track
section from a peaker voltage transformer PT
of special construction. This transformer PT
is shown diagrammatically, and comprises a pri
mary 1 connected to the A. C. line circuit 6, and a
secondary winding .8 connected across the track 50'
rails I in series with the usual limiting resistance
or reactance 9. In the type of peaker voltage
transformer PT contemplated, the core for the
secondary 8 has a small magnetic section as com
pared with the core for the primary 1, and is also
2
2,123,965
provided with a magnetic shunting core l0 of
appropriate section with a reluctance gap.
The purpose of this peaker voltage trans
former PT is to provide high peaked secondary
voltage waves of short duration. Referring to
Fig. 3, if the primary flux is represented by the
ance at the wheel contact by an ionization effect,
and enable effective shunting with dirty or rusty
track rails and light-weight equipment in a man
ner not obtainable with the ordinary track cir
cuit arrangement.
In this connection, it will be noted that the
sign curve A, the parts are so proportioned that
peak voltages are periodically applied at frequent
the secondary flux corresponds approximately
intervals and are available to break down the re
sistance of the wheel contact, as the car or train
with that indicated by the dot-and-dash curve
10 B, and the secondary voltages are those illus
trated by the curve C.
These curves of Fig. 3 are
merely illustrative of the principles and opera
tion, and are not intended to show quantitative
values or relations. These characteristics are
15 obtained by proportioning the cross section of
the core for the secondary winding 8 so that it
becomes substantially saturated with a low ?ux
density, the primary ?ux also passing in part
through the shunting cores I0 and reluctance
air-gap.
With such a peaker voltage transformer PT
producing secondary voltages as indicated by the
moves along the track and its wheels contact with 10
successive points on the rails, and with the re
sistance once broken down it will remain of low
value until the train has left and an opportunity
for soiling and oxidization of the rail surface has
been presented.
The particular embodiments of the invention
shown and described are merely illustrative; and
various adaptations, modi?cations, and additions
may be employed, without departing from‘ the
principles and mode of operation of the inven 20
tion.
What I claim is:—
curve C in Fig. 3, it is apparent that the maxi
mum or peak Voltage which may be applied across
25 the track rails to produce an average or e?'ective
1. In an alternating current track circuit for
railroads, the combination with a section of rail
relay energizing current, is much greater than
with the ordinary sine wave of voltage commonly
employed with alternating current track circuits.
According to the principles of this invention, it
30 is contemplated that these maximum or peak
having two windings one connected across the
track rails at one end of said section and the'
other connected to a source of substantially sine
wave alternating current, a peaker voltage trans
former for changing a substantially sinewave 30
voltages will serve to break down or ionize the
rail ?lm and render the wheel shunt effective to
conduct current at a lower inter-rail potential.
These peak voltages for breaking down rail ?lm
35
are repeatedly applied so as to be effective as the
wheels move to different spots on the track rails.
The track circuit organization of this inven—
tion may be advantageously employed with double
rail track circuits for electric propulsion roads,
way track, a polyphase alternating current relay
alternating current voltage to a very peaked
alternating current voltage comprising a core
structure for very loosely inductively coupling a
primary winding and a secondary winding wound
thereon, said core structure also including a
leakage magnetic path for passing magnetic flux
linking only said primary Winding, and means for
connecting said primary winding to said source
and connecting said secondary winding across
where impedance bonds are used, as illustrated in
the track rails at the other end of said section,
Fig. 2. With such an arrangement, the imped~
ance of the bond is materially increased by the
use of the time-spaced peaked voltages obtained
from the peaker voltage transformer PT, as com
45 pared with the impedance of an equivalent core
section and number of turns excited with alter
nating current of the sine wave form. Conse
quently, the desired impedance across the bond
to provide proper excitation of the track relay T
50 may be obtained by use of this invention by fewer
turns, thereby reducing the cost of the bond
and lowering its resistance to the propulsion
whereby the winding of said relay connected
across the track rails is energized by a voltage
which has a high ratio of'maximum to average
value so that the voltage peaks of the alternating
current.
current voltage may act to break down the ?lm
resistance existing between wheels and rails to
cause more effective wheel shunting without sup
plying su?icient effective current to maintain
said relay energized during the presence of a
train.
50
2. In a track circuit for railway signalling sys
tems, the combination with a section of railway
track isolated from adjacent track sections by
One important characteristic of this invention
insulating joints, an alternating current track
55 is that it assures reliable shunting of the ordinary
relay connected across the track rails at one end
of said section and of a construction to assume
an energized condition when an alternating cur
rent of a certain effective value derived from a
source of substantially sinewave form and of a
certain voltage is connected across the rails at
the opposite end of said section but assumes a
deenergized condition upon entrance of a train
track circuit under unfavorable conditions of rail
surface, weight of equipment, and ballast condi
tions. This desirable characteristic is due to the
application of high peaked voltages to break down
60. the ?lm or coating on the track rails, thereby
assuring a shunting effect of the wheels and axles
of a car or train under conditions where a lower
voltage would be insu?icient.
The resistance of the wheel contact is found
65 to vary greatly with the conditions of the rail
surface and the weight of the equipment; and it
into said section, and a peaker voltage trans
former for transforming sinewave form alter
nating voltage into a peaked alternating voltage 65
connected between a source of alternating cur
appears that in many cases voltages much higher
rent of substantially sinewave form and said
than the relatively small voltages, of about 2
volts normally employed for track circuits are
70 necessary to break down the resistance of the
wheel contact to a point where ionization and
actual shunting of the track relay takes place.
opposite end of said section to supply alternating
voltage of peaked wave form to said opposite end
The peak voltages provided by this invention,
which are many times those commonly used in
75 track circuits, apparently break down the resist
having a maximum value which is much greater 70
than the maximum voltage of said certain alter
nating voltage but supplies a current of only said
certain effective value to said relay, whereby a
high ratio of maximum to effective track circuit
voltage is established in the track circuit so that 75
2,123,965
the high voltage peaks of the alternating voltage
may act to break down the ?lm resistance ex
isting between wheels and rails to cause more
effective wheel shunting without supplying suf
?cient e?ective current to maintain said relay
energized during the presence of a train.
3. A track circuit for railway tracks in which
due to atmospheric conditions a high resistance
?lm forms on the track rails, the combination
10 with a section of railway track isolated from ad
jacent track sections by insulating joints, a two
element alternating current track relay having
its track circuit element connected across the
track rails at one end of said section and having
its local element connected to a source of sub
stantially sinewave form alternating current, a
series impedance, and a peaker transformer en
ergized from said source and supplying peaked
wave form alternating voltage to the other end
3
of said section through said series impedance to
supply peaked alternating current to the track
element of said relay, said peaker transformer
transforming said alternating voltage of sub
stantially sinewave form into a peaked Wave form
voltage which has a very high maximum volt
age for each unit of e?ective voltage as com
pared with the maximum voltage of sinewave
form of unity effective value, whereby a high
ratio of maximum to effective track circuit volt 10
age is established in the track circuit so that the
high voltage peaks of the alternating voltage
may act to ionize the ?lm and break down the
resistance existing between wheels and rails to
cause more e?ective wheel shunting without sup
plying su?icient effective current in the track
element of said relay to maintain said relay en
ergized during the presence of a train.
FRANK X. REES.
15
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