Patent GB-280562-A (GB)
Title: Improvements in or relating to electric remote control devices
IPC: H04Q9/04
Filed: 1927-11-10
Abstract: 280,562. Siemens & Halske Akt.- Ges. Nov. 11, 1926, [Convention date]. Selective distant control systems; tell-tale apparatus.- In distant control systems of the kind in which the positions of switches or other units at the substations are indicated by hand-operated indicators at a supervisory station, the indicators are coupled to contacts electrically connected to contacts controlled by the switch or other substation unit so that an alarm is given if the position of the indicator is not in agreement with that of the corresponding substation unit. The indicators may be interlocked with the controlling switches. In the system described, an arm 3 at the substation moves over contacts, such as 9, 10, connected to magnets 7, 8 controlling switches 6, 39, &c., and over contacts, such as 23, 123 which serve to indicate the position of such switches. At the supervisory station, an arm 1 moves synchronously over contacts, such as 11, 12, connected to the contacts of controlling switches 15, 36, and over contacts 24, 124 connected to contacts such as 25, engaged by a spring 26 in one position of the hand-operated indicator 33, there being one such indicator for each substation switch. Each indicator is associated with a shutter 29 released by a magnet 27. To close the switch 6, the operator moves switch 15 to magnet 13, thereby energizing magnet 7 over contacts 11, 1, 3, 9. Switch 6 closes contact 22, so that a further circuit is subsequently closed over contacts 22, 23, 3, 1, 24, 26,. and magnet 27, which releases the shutter 29, opening the circuit of the control switch 15 and closing a circuit for an alarm bell 31, which rings until the attendant moves the indicator 33 into its closed position, thereby re-setting the indica. tor 29 and opening contacts 26, 30. A mark on the indicator 33 comes into line with marks 61 on the casing to indicate that the switch is closed or the handles of the indicators may electrically control similar indicators, or may themselves rotate in the recesses of a cover plate provided with marks such as 61. Similarly when the sub. station switch is opened, either by the switch 15 or automatically by an overload relay at the substation, a circuit is closed over contacts 122, 3, 1, 124, 32 for magnet 27, which releases the shutter 29 &c. as before. In order to ensure that a control switch, such as 15, is brought back to its central position before the corresponding position indicator can be turned over, and thereby prevent the possibility of a substation switch 6 being repeatedly closed by switch 15 and opened by an overload relay, the control switch may be interlocked with the position indicator as shown in Fig. 2, in which the switch comprises a disc 101 with a projection 47 controlling contacts 13, 14. The disc 101 has a key-hole, through which is inserted a key shown in section in Fig. 2 and formed with projections 103. A cam disc 49 on the indicator has recesses 104, 105 which prevent the indicator being turned when the key is in position, and the arrangement is such that the key can only be withdrawn when the control switch is in its open position. In order that the attendant may know whether a substation switch has been positioned by a control operation performed by him, or automatically e.g. by an overload relay, a separate indicator 53, Fig. 2, is secured to a " drag " disc 54, which has a recess engaged by a pin 58 on a wheel 56 gearing with a wheel on the disc 101, the indicator 53 thus indicating the last control position of the switch 15. If the substation switch is opened automatically immediately after it has been closed by the operator, the " closed " signal would not be received at the supervisory station. To avoid this, a retardation device may be arranged between the switch 6 and the contacts 22, 122, such that when the switch is opened, the opening of the contact 22 and the closing of contact 122 are retarded.