GB642495A - Self checking means for apparatus for comparing the impedance of two electric circuits - Google Patents

Self checking means for apparatus for comparing the impedance of two electric circuits

Info

Publication number
GB642495A
GB642495A GB19499/48A GB1949948A GB642495A GB 642495 A GB642495 A GB 642495A GB 19499/48 A GB19499/48 A GB 19499/48A GB 1949948 A GB1949948 A GB 1949948A GB 642495 A GB642495 A GB 642495A
Authority
GB
United Kingdom
Prior art keywords
relay
bridge
periodic
balanced
loop
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB19499/48A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Mobility Ltd
Original Assignee
Westinghouse Brake and Signal Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Brake and Signal Co Ltd filed Critical Westinghouse Brake and Signal Co Ltd
Publication of GB642495A publication Critical patent/GB642495A/en
Expired legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L1/00Devices along the route controlled by interaction with the vehicle or train
    • B61L1/18Railway track circuits
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R17/00Measuring arrangements involving comparison with a reference value, e.g. bridge

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Train Traffic Observation, Control, And Security (AREA)

Abstract

642,495. Indicating presence of railway vehicles. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 21, 1948, No. 19499. Convention date, Sept. 6, 1947. [Class 105] [Also in Group XXXVI] A relay in the output diagonal of a Wheatstone bridge and released when the bridge is balanced, is arranged so that when released it causes the bridge to become unbalanced so that the relay is then again energized, whereby the unbalancing is removed to drop the relay again, these actions being repeated and the consequent periodic actuation being shown by an indicator. The invention is described with reference to detecting the presence of a vehicle on a stretch of railway track. A loop L, the inductance of which is altered by the presence of a vehicle, is arranged in an A.C. bridge circuit 1, 2, 3, 4 whose output is amplified at V3, V4, V6 and applied to gas-filled valve V5 whose anode circuit is fed with A.C. and includes a direct current relay CF. The bridge is balanced only when arm 4-2 includes a resistor R1 placed in circuit by a front contact b of the relay CF. Accordingly, when relay CF is energized, the bridge becomes balanced to cause the relay CF to drop and thereby to unbalance the bridge to re-operate the relay CF which thus continues in periodic operation. The periodic operation of relay CF controls slow release relays FP, CD to light lamp G. With a vehicle present in the loop L, the bridge remains permanently unbalanced and relay CF thus remains actuated so that while relay FP remains up the relay CD drops, thus lighting lamp R. A fault produced by ageing of valve V5 results in relay CF remaining unenergized and the lighting of lamp R. The resistance R1 is such that the periodic change of potential in the bridge arm is less than that arising on the minimum change of loop impedance required to be detected. The relay CF is made to respond to this smaller change, arising from the periodic action of R1, by adjustment of the cathode voltage on the valve V5. In a modification, the resistance R1 is connected between point 1, 4 instead of 4, 2, Fig. 2 (not shown), but over a back contact of the relay CF and giving an unbalancing effect. The rails 1a, 1b may be connected by low resistances or condensers to reduce leakage of any current induced in the rails through the ballast. The invention is applicable to the detection of movable objects on a road or an airfield..
GB19499/48A 1947-09-06 1948-07-21 Self checking means for apparatus for comparing the impedance of two electric circuits Expired GB642495A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US642495XA 1947-09-06 1947-09-06

Publications (1)

Publication Number Publication Date
GB642495A true GB642495A (en) 1950-09-06

Family

ID=22054604

Family Applications (1)

Application Number Title Priority Date Filing Date
GB19499/48A Expired GB642495A (en) 1947-09-06 1948-07-21 Self checking means for apparatus for comparing the impedance of two electric circuits

Country Status (1)

Country Link
GB (1) GB642495A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2177216A (en) * 1985-07-05 1987-01-14 Baumer Electric Ag Proximity switch

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2177216A (en) * 1985-07-05 1987-01-14 Baumer Electric Ag Proximity switch
GB2177216B (en) * 1985-07-05 1989-07-19 Baumer Electric Ag Proximity switch

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