US861015A - Block-signal system. - Google Patents

Description

UNITED STATES PATENT OI FIQE.

ELMER F. BLISS, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEIVI.

Specification of Letters Patent.

Patented July 23, 1907;

Application filed March 7, 1906. Serial No. 304,649.

To all whom it may concern:

Be it known that I, .ELMER F. BLIss, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York,have invented certain new anduseful Improvements in Block-Signal Systems, of which the following is a specification.

My invention relates to block signal systems, and its object is to provide simple and efiicient means for protecting the source of current connected to the track circuit from an abnormal flow of current when shortcircuited by a train. I

It has been proposed heretofore to protect the source by means of a resistance inserted when the current rises above a predetermined amount.

My invention consists in cutting a portion of the source out of circuit upon an abnormal flow of current. By means of this arrangement the protective resistance may be greatly reduced in amount, or even omitted entirely, so that the loss of power is reduced and the efiiciency of the system increased.

While my invention in its broadest aspect is not limited to a signal system employing any particular form of current, it is particularly advantageous for use in alternating-current signal systems in which the track circuits are supplied from transformers. In a directcurrent signal system in which the track circuits are supplied from batteries the internal resistance of the battery is ordinarily high enough to prevent a flow of current large enough to injure the battery when shortcircuited bya train on the block, but when a transformer is the source of supply, the internal resistance is small.

I shall,'accordingly, describe my invention as applied to an alternating signal system, but it will be understood that it is equally applicable to a direct-current signal system, if it is desired to protect the direct-current source against an abnormal flow.

My invention will best be understood by reference to the accompanying drawing, which shows diagrammatically a block signal system provided with protective devices arranged in accordance with my invention.

In the drawing R, R, represent the track-rails of a road which, in the present case, is assumed to be an electrically operated road, the supply conductors for the power-current being indicated at T.

A, A, represent line-wires carrying alternating-current at high tension, which is supplied to the track circuit through the step-down transformers B, B.

C, C, represent transformers having their primaries supplied from the step-down transformers B, B, and

their secondaries connected to the track circuit.

7 D, D, represent transformers connected to the other ends of the blocks,their secondaries supplying a coil of the relays E, E. I

In order to provide a return path for thepower-current the central point of the secondaries of each transformer C is connected to the central point of the primary of transformer D at the adjacent end of the adjacent block. The adjacent blocks are thus connected at equipotential points with respect to the signal current, and this connection enables the rails to serve as conductors for both the signal-current and power-current without mutual interference, as is fully described in latents Nos; 645,907 and 647,741, issued to Badell, dated March 20, 1900, and April 17, l900,respectively. The relays E are shown as of the polyphase induction type, one primary coil being supplied from the track transformer D and the other directly or through a transformer from the alternating-current supply conductors A. When both phases of the relay are energized, as is the case when no train is on the track, the contact member carried by the armature of the relay closes a circuit comprising the signal operating mechanism F of the signal H and asuitable source of current G. The signaloperating mechanism is merely indicated diagrammatically, as it forms no part of the present invention, and any well-known type of operating mechanism may be employed. I representsa relay in series with the secondary of the transformer B and the primary of transformer C. J represents an impedance, preferably a non-inductive resistance.

The operation is as follows: Normally the relaysI are in the position shown, in which the full voltage of the secondaries of transformers B are supplied to the pri maries of transformers C. When a train on a block short-circuits the secondary of a transformer C, thereby producing an abnormal flow of current, the correspondingrelay I draws up its armature, cutting out a portion of the secondary oi transformer B and including in circuit the impedance J. In this manner, the voltage supplied to the track circuit is reduced and the flow of excessive current due to the short-circuiting effect of the train is prevented. Since the impedance .T is normally out of circuit, it does not impair the eiliciency of the system.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a block signal system, in combination with the rail circuit of a block, a source of voltage supplying the rail circuit, and an overload relay in series with said source arranged to cut a portion of said source out of circuit upon an abnormal flow of current therefrom.

In a block signal system, in combination with the rail circuit of :1 block, a source of voltage supplying the rail circuit, an overload relay in series with said source arranged to cut :1 portion of said source out of circuit upon ,an abnormal fl0w of-current therefrom, and an impedance arranged to be inserted in series with said source by the gredncingthe number of effective secondary turns of said transformers upon an abnormal flow of current therein. 4. In an alternating-current block signal system, linewires extending along the track, supply connections from the line-wires to the rail circuits of the blocks, transformers comprised in'said'connections, and overload relays in said connections comprising contacts arran ed to cut a portion ot the secondarj turns of said transformers out of circuit.

5. In an alter-nating-current block signal system, linewires extending along the track, supply connections from the line-wires to the rail circuits of the block, transformers comprised in said connections, and means for increasing the ratio of effective primary to eifective secondary turns in said transformers upon abnormal flow'of current therein.

In witness whereof, I have hereunto set my hand this 6th day of March, 1906.

' ELMER F. BLISS.

Witnesses:

BENJAMIN B. HULL, HnLnN ORFoRD.

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