Patent GB-316228-A (GB)
Title: Improvements in or relating to electric signalling systems
IPC: G01R17/08
Filed: 1929-07-24
Abstract: 316,228. Siemens & Halske Akt.- Ges. July 25, 1928, [Convention date]. Tell-tale apparatus.-In a system for repeating at a distance variable values such as the indications of a measuring instrument the position of a movable member, &c., a primary torque, dependent upon the value is balanced by an adjustable electrical or mechanical force the value of which is transmitted for distant indication. Transmitting apparatus, Figs. 1 and 3. As shown in Fig. 1, a moving coil measuring instrument 1 has a pointer 4 adapted to be periodically depressed by a member 19 into engagement with one or other of the contacts 17, 18. The spindle of the instrument carries a loop 5 which cooperates with three springs 6 of different strengths, e.g. in the ratio 2: 4: 8 under the control of corresponding relays 12, 13, 14. The primary force acting on the instrument may in this way be balanced to return the pointer to zero by suitably energizing the relays 12, 13, 14, and thereby permitting the springs 6 to engage the member 5. The relays 12, 13, 14 are energized in sequence under the control of contact apparatus shown in Fig. 3 and selection of the appropriate relays to secure balance is determined over circuits including contacts 17, 18. An insulating disc 30, Fig. 3, rotated in a clockwise direction carries contact rings 31, 32 having projections 33, 36 respectively. The projection 33 during rotation energizes successively the relays 12, 13, 14, which provide locking-circuits over contacts 122, 132, 142. If say during testing the torque provided by the relay 12 is insufficient to cause balance, a circuit for the polarized relay 34 is completed over contact 18 and the locking circuit is maintained over the projection 36 of the contact ring 32 and the contact 35. In this manner the relay 12 is maintained energized and its corresponding spring 6 remains effective. This process is repeated for the remaining relays until the pointer 4 is zeroized and the relay 34 is reversely energized to open the contact 35 and thereby prevent locking of the remaining relays. Any number of balancing springs 6 and corresponding relays may be provided. Each relay has a pair of contacts 124 which effect the transmission of appropriate signals to the receiver. In a modification instead of springs, resistances of different values may be switched into circuit with an auxiliary coil on the instrument shaft in different combinations to effect balance. Receiving apparatus. Relays corresponding to the relays 12, 13, 14 may be provided at the receiving station and according to the operated relays at the transmitter, impulses are transmitted over synchronously rotated distributors at the transmitting and receiving stations to operate the receiver relays and apply torques to the spindle of a spring-controlled indicating instrument. In a modification the receiver relays switch resistances into or out of the circuit of a voltmeter the arrangement being such that the total resistance remains unchanged. Modified transmitting and receiving apparatus. In order to prevent faulty operation of the receiving apparatus by reason, say of disturbing influences present on the line wires, arrangements may be provided whereby the receiving apparatus is operated only upon the receipt of a number of impulses characteristic of the transmitted signal. For example, each relay 12 &c. may produce impulses of reverse polarity in order to effect the desired operation at the receiving station. A receiving apparatus of this type is shown in Fig. 5 wherein one of a plurality of indicating instruments V may be selectively operated by a relay 101 which is responsive to transmitted impulses. The transmitting apparatus is such that for each relay 12, 13, 14, Fig. 1 which remains operated a positive and then a negative impulse is transmitted and for each deenergized relay, first a negative and then a positive impulse is transmitted to operate the receiver relay 101. These impulses are transmitted over the contacts of a distributor which moves synchronously with the arm 102 of a distributor 100 at the receiving station. The arm 102 carries contacts 103, 104, 105 which respectively co-operate with contacts 301 - - 306, 201 - - 206, 106. According to which relays 12, 13, 14 are energized positive impulses are transmitted when the arm 102 co-operates with the corresponding contacts 201, 202, 203 to energize correspondingly one or more of the relays 211, 221, 231 which are locked over the lead 110. The positive and negative impulses for each relay 12, 13, 14 cause the operation of relays 301a - - 306a through the contacts 301 - - 306 and complete a circuit over armature contacts 301<b> - - 306<b>. In the event of a fault in the line and the consequent inaccurate operation of the relay 101 the circuit over the contacts 301<b> &c. would remain open to prevent further operation of the receiver. The appropriate indicating instrument V is selected during the second half-revolution of the distributor 100. One or more of the relays 241, 251, 261 are energized according to whether positive impulses are received by the relay 101 when the arm 102 co-operates with contacts 204, 205, 206. Relays 241. 251, 261 operate combinations of contacts 241<b>, 251<b>, 251<c>, 261<b> &c. which co-operate to effect a selection e.g., the relay R the circuit of which is completed over the contacts 301b - - 306<b>. The relay R operates the contacts R<11>, R<12>. R<21> &c. and the appropriate relays in the groups 61, 62, 63 are energized corresponding to the energized relays in the groups 211, 221, 231; 12, 13, 14. The operated relays in the groups 61, 62, 63 adjust the value of the resistances controlling the indicating instrument V. The total resistance between the mains is maintained constant independent of the energization of the relays by the provision of pairs of resistances for each relay, one resistance being operative while the other is short circuited. Instead of utilizing positive and negative impulses for transmission, indication and selection may be effected by impulses of single polarity operating a relay 101 having a spring-controlled armature. Moreover high-frequency impulses transmitted by wireless or over line wires may be employed. Signalling sum difference product or ratio of a plurality of indications. The sum of a plurality of values may be indicated by an instrument which is under the control of a plurality of torques corresponding to torques for the primary values; alternatively a single instrument may be associated with the plurality of indicating instruments used in association with resistances in the manner shown in Fig. 5. To signal a sum or difference of two values one value may act on the pointer of the transmitting instrument and the other value on the scale in the same or opposite sense. Products or ratios may be obtained by using suitable receivers of known type. The Specification as open to inspection under Sect. 91 (3) (a) states that apparatus of the type shown in Fig. 5 may be employed for selectively controlling apparatus units. This subject-matter does not appear in the Specification as accepted.