US2490810A - Fault signaling impulse repeater - Google Patents

Description

Dec. 13, 1949 H. HoRwlTz I FAULT SIGNALING IMPULSE REPEATER Filed Dec. 28, 1945 ATTOR EY Patented Dec. 13, 1949 FAULT SIGNALING IMPULSE REPEATER Henry L. Horwitz, Jamaica, N. Y., assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application December 28, 1945, Serial No. 637,661

3 Claims.

This invention relates to improvements in fault signalling impulse repeater, particularly to impulse repeaters for use in automatic telephone systems, and has for an object to provide in an impulse repeater an improved arrangement for disconnecting the repeater in the event that an outgoing trunk, to which the repeater is oonnected, includes a faulty condition.

' Another object of the invention is to provide an improved impulse repeater in which a faulty condition is revealed on a connected outgoing trunk only upon the repeater being seized by an incoming line.

Still another object of the invention is to provide an improved repeater in which, upon a faulty outgoing trunk being revealed, the repeater is automatically made busy to further calls until the fault has been corrected.

A further object of the invention is to provide an improved repeater in which an indication of a faulty outgoing trunk is not effected during the idle period of the impulse repeater.

With the above objects in View, one embodiment of the invention discloses an impulse repeater of Well-known type, to which is added a self-locking cut-oli relay, which is controlled by a called subscribers supervisory relay bridged across the outgoing trunk. Should a fault, such as a ground, open circuit, or short circuit, appear in the outgoingr trunk, the cut-ofi relay, which is normally ineffective, will be operated upon seizure of the impulse repeater by a calling party, Whereupon the preceding switches will be released, an alarm lamp will be energized for attention of the maintenance attendant, and the repeater will be rendered busy to further incoming calls until the fault has been cleared. Upon clearance of the trouble on the outgoing trunk, the cut-off relay may then be released by the attendants inserting a test plug into the repeater test jack, which is adapted to release the cut-oli relay, the repeater thereby being put into condition for further calls.

A more complete understanding of the invention will be obtained from the following description of a preferred embodiment thereof, taken in conjunction With the accompanying drawing in which a circuit arrangement of an impulse repeater is interposed between a calling subscribers loop and an outgoing trunk to a called subscribers loop of an automatic telephone system.

Referring now to to the drawing, thereis shown an impulse repeater connected at the left, as Viewed in the drawing, though suitable switches (not shown), such as selectors, to a calling subs'cribers line or loop; and at the right to an outgoing trunk, which is connected, in a manner well-known in automatic telephone practice, to a called subscriber. Before proceeding With a description of the circuit, however, the manner of illustrating the relays and associated contacts on the drawings will be first explained. It will be observed that each relay is identiiied by a lettered character with a horizontal bar underneath the character and a numeral thereunder. The leftered character indicates the designation of the relay, while the numeral thereunder indicates the number of contacts associated with the particular relay. For example, relay indicates a relay having one contact, which is designated El, while relay indicates a relay having four contacts, which are designated BI, B2, B3, and Bai'. The contacts are, as illustrated, disposed in the circuit in a manner to shorten the leads interconnecting the component elements of the circuit.

The invention will be more readily understood from a detailed description of the operation.

Assuming a call to have been originated at a subscriber station (not shown) a circuit is closed upon removal of the receiver from the mounting (not shown), which closure energizes line relay A in a circuit that can be traced from grounded battery through upper Winding of relay A, nonoperated break contact Dfi, over conductor, through conventional switches and calling subscribers loop (not shown), back over -iconductor, and thence through non-operated break contaot'DS to ground via lower winding of relay A. Relay A operates, contact Al closing the positive conductor of the outgoing trunk and contact A2 closing an obvious operating circuit for relay B. Relay B in operating at contact BI prepares an operating circuit for relay C; at contact B2 prepares an operating circuit for relay F and relay CO; at Contact B3 closes the conductor of the outgoing trunk and in conjunction with contact A! connects an energizing circuit for relay E; and at contact B4 grounds the test lead P.

The circuit for energizing relay E may be traced from a grounded battery connection provided by an impulse relay (not shown) in the distant cnice, over vthe conductor of the outgoing trunk, through make contact B3, break contact C I right Winding of relay F, break contact D2, upper winding of relay E, make contact Al and thence over the positive conductor of the outgoing trunk to ground furnished by the aforesaid impulse relay. Relay E is energized and opens at contact El an operating circuit for relay CO, which, in turn, has been closed simultaneously at contact B2. In other words, relays B and E operate substantially at the same' time, so thatslovv operate relay CO is' not permitted to operate. Relay F is an electro-l polarized relay and, as is Well-known, will not operate until the polarity of the outgoing trunlr is reversed, the left and right windings of thisrelay producing substantially equal amounts of opposing magnetic flux.

The subscriber now operates his dial (not shown) and intermittently interrupts the calling loop circuit, line relay A releasing in accordance with the interruption in the Well-known manner.

At the rst release of relay A, contact AI retracts and open-s the outgoing trunk circuit and contact A2 closes an operating circuitV for relay C. This circuit may be traced from grounded battery through winding of relay C, make contact BI, and to ground through retracted contact A2. Relay C operates and at contact CI short circuits relay E; at contact C2 places a further ground on the test lead P; and at contact C3 opens a circuit to relay CO. It Will be noted that contact C3A opens the circuit for relay CO prior to retraction of contact El upon release of relay E, thereby preventing theA cut-oir relay CO from operating during the impulsing period. Relay C is of the slow-release type and continues operated only during the impulsingperiod.

Upon cessation of dialing by the calling party and assuming that the called party answers, the called partys battery feed relay (not shown) operates and reverses the current over the and conductor-s of the outgoing trunk. Relays F and D then operate in the usual manner to provide reversed battery supervision to the calling party, as is Well known in the art.

At the end of the conversation, relays A, B, D, and F release. Since relay C receives one impulse at contact A2, the operating circuit of relay CO is still interrupted at contact C3 until contact B2 i-s retracted, thereby maintaining the cut-orf relay inoperative. It is thus apparent that at no time during the normal operation of the repeater is the cut-ofi relay operated, particular precaution being taken to prevent operation thereof.

Assuming now that the outgoing trunk includes a faulty condition, such as an open, a ground, or

a short, or further, a disconnected selector at the i distant oice, it will be seen that relay E cannot be energized in response to seizure of the repeater by a calling party. In other Words, the battery and ground furnished by the impulse relay at the distant oftice will not be available for energizing relay E. Thus, upon operation of relay A and subsequent operation of relay B, contact B2 completes an operating circuit for relay CO which may be traced from grounded battery through the 1300 ohm winding of relay CO, back contact Ei, back contact C3, and make contact B2 to ground. Relay CO, in operating, at contact CO! provides a locking circuit to ground via 1000 ohm winding thereof and resistance R, which is preferably non-inductive; at contact CO2 energizes an obvious alarm circuit, including lamp L, for the attention of the maintenance attendant; and at contact CO3 disconnectsthe test conductor P from ground, thereby releasing the previous switch train. In view of the release of the preceding switch train, relays A and B release. Contact B4, in retracting, re-connects ground to the test lead P via the make contact CO3, thus guarding this repeater against further intrusion and preventing seizure thereof until the faulty condition has been corrected.

The maintenance attendant, now aware of the trouble condition, plugs the well-known hand test telephone set into the test jack, which comprises springs Tl, T2, and T3, as shown. Battery and ground are connected through springs TI to operate relays A and B in the hereinbefore-described manner, and spring T2 and T3 are bridged, with the 1000' ohm holding Winding of relay CO short circuited. If the'faulty condition still exists on the'outgoing trunk, relay CO will not release because the hereinbefore-traced operating circuit thereof is still maintained by make contact B2 and back contacts C3 and El, relay E failing to operate in view of the continued fault on the outgoing trunk. The attendant, in removing the test phone, will re-introduce the 1000 ohm holding coil of relay CO so that thisrelay continues in an operated condition.

If the test phone is plugged into the test jack after the outgoing trunk has been repaired, relay E, in operating, at contact El opens the operating circuit for relay CO and the test jack short circuits the holding Winding thereof. Consequently, the cut-off relayCO releases and at contact COI opens the holding circuit, at contact CO2 extinguishes the alarm lamp L, and atcontact CO3 removes the guarding ground from test conductor P, thereby conditioning the repeater for further use.

While this invention has been shown and described in accordance with the preferred embodiment merely for the purpose ofV illustration, it is, of course, understood that various modications may be made and that the features thereof may be applied to many other elds without departing from the scope of the invention, as dened in the appended claims.

What is claimed is:

l. In a signaling system of the automatic telephone type in which digital impulses are impressed upon a line, means for repeating said impulses over an outgoing trunk to a distant switch, said repeating means including a supervisory relay bridged across said outgoing trunk, said relay being energized `by a source of energy supplied from said distant switch, a cut-off relay immediately responsive to release of said supervisory' relay upon occurrence of a fault on said outgoing trunk, means responsive to said cut-off relay for indicating said fault, and means responsive tov said cut-oil relay for rendering said repeater busy to further incoming calls.

2. An impulse repeater adapted for interconnecting an incoming line and an outgoing trunk, including a rst relay adapted to be energizedA under control of said line, a vsecondrelay disposed across said trunk, a source of energy connected to said trunk for energizing said second relay, said second relay being ineiective upon occurrenceofV a faulty condition on said trunk, a third relay of the slow-operating type, an` operating circuit for said third relay, said circuit under control of said first and said second" relays, alarm means to in dicate a fault on said trunk and means to render said repeater busy to said line, both said means under controlr of said thirdy relay.

3. An impulse repeater as` claimed in claim 2 further comprising'meansfor rendering said'thirdf relay inoperative upon clearance of the fault on said trunk.

HENRY L. HORWITZ.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Levy Nov. 21, 1933 Number OTHER REFERENCES Automatic Telephony by A. B. Smith and W. L. Campbell, pages 47-50, 2nd ed. 1921, McGraw- Hi11 Book Co.

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