US1562211A - Supervisory system - Google Patents
Supervisory system Download PDFInfo
- Publication number
- US1562211A US1562211A US508443A US50844321A US1562211A US 1562211 A US1562211 A US 1562211A US 508443 A US508443 A US 508443A US 50844321 A US50844321 A US 50844321A US 1562211 A US1562211 A US 1562211A
- Authority
- US
- United States
- Prior art keywords
- distributor
- station
- switches
- distributors
- operated
- 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 - Lifetime
Links
- 239000004020 conductor Substances 0.000 description 10
- 238000004804 winding Methods 0.000 description 5
- 230000011664 signaling Effects 0.000 description 2
- 241001464057 Electroma Species 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
Definitions
- This invention relates to control and s11- pervisory systems, and particularly to such,
- switches or other'apparatus may be remotely controlled and supervised.
- the invention is particularly adapted for use in connection with circuit controlling apparatus employed on power lines where it is desired to control a number of distant circuits from a central station.
- An object of the invention is to provide a system of this character which includes a minimum number of operating elements, and which is reliable and rapid in operation.
- Another object of the invention is to provide means for indicating at the central station the condition of the apparatus at a remote station.
- the receiving distributor at each station operates synchronously with the transmitting distributor at the other station, the brush arm of each of the distributors, which is frictionally mounted on a continuously rotating shaft being adapted t'o be arrested periodically and then released automatically throdgh the instrumentalitiy of the other distributor.
- the transmitting distributor at the control station transmits controlling impulses which are selectively distributed by the corresponding receiving distributor to electromagnetic devices through which the desired switch controlling or other remote operation is performed.
- the controlled apparatus mechanically operates switches which supply current to be transmitted in impulses by "the transmitting distributpr at the remote sta- Application filed October 18, 1921. Serial No. 508,443.
- the system may be considered as having two parts. One part transmits impulses to the mechanism to be controlled, and the other part transmits impulses generated at the controlled mechanism to operate the supervisory apparatus at the central station.
- Another object of the invention is to provide means for repeating the controlling impulses at regular intervals, so that if the controlling means does not immediately operate at the local station, succeeding 1 mpulses will insure its operation if such is possible and with little delay.
- Another feature of the invention is the manner in which synchronism is secured between the transmitting and receiving distributors of each set.
- the distributors are in two pairs. These pairs do not operate simultaneously but successively. tion of one set of distributor arms, they are locked, and, as they near the completion of a revolution, release the other set of distributor arms which go through a similar cycle of operations to release the first set. This operation is continually repeated.
- the electrically operated devices disclosed here consist of'power switches of-which 1 and 2 are That is to say, after a full revolu- At station A there is provided a plurality of manually operated controlling switches of which 8 and 9 are typical, and which correspondto the power switches 1 and 2, re-
- Two sources of current 10 and 11 having opposite poles grounded are each associated with the switches 8 and 9 in such a manner that the moving element of these switches may be connected with negative or positive current by operating them in opposite directions.
- the moving elements of switches 8 1 and. 9 are associated with se ner hereinafter described, is operated in synchronism with the transmitter 12.
- pulses from the line 7 are transmitted to polarized relays 14 and 15 which correspond to the switches 8 and 9 and the power switches 1 and 2 respectively, through the collector ring 42, brush arm and segments of a receiving distributor 13.
- the polarized re lay 14 operates to energize or deenergize the electromagnet of .the power switch 1 to open or close it, depending upon the polarity of the current impulse transmitted to the polarized relay.
- the polarized relay 15 operates or releases .power switch 2, depending upon the polarity of the impulses transmitted thereto.
- Power switches 1' and2 are provided with mechanically operated switches 16 and 17 which have alternate contacts connected to sources of current 18 and 19 of opposite polarity.
- the power switches are mechanically connected with the moving elements of these switches 16 and 17 so that when the power switches open or close they cause switches 16 and 17 to connect with current of one or theother polarity.
- the moving elements of the switches 17 and '16 areelectrically connected to successive segments of a rotary transmitting distributor 20 through the brush arm and collector ring 47 of which electrical connection ismade with the line 7.
- a corresponding rotary receiving distributor 21 is located at the central station A and is connected through its collector ring 49 and brush arm to the line 7.
- -Polarized relays 22 and, 23 are connected to successive segments of the receiver 21 so that the impulses transmitted from the sources of current 18 and 19, through the switches 16 and 17 are transmitted to the polarized relays 22 and 23, respectively. It
- switches-such as 16 and 17 will be associated with corresponding segments of dis- I tributors 13, 21,12 and 20, respectively, lead wires being shown for this purpose.
- the power switch 1 is in its open positioh, as shown in the drawing, positive current is transmitted through the segment' 55.0f' the distributor 2O asthe brush arm thereof revolves, through the line 7, through ⁇ the collector ring 49 and brush arm of re-- thus lighting the lamp and showing that the power switch 1 is open.
- the system comprises twoparts, one by means of which impulses are transmitted from the central station through the distributors 12 and 13 to the power switches at station B, and the other by means of which impulsesunder the control of the power switches 1 and 2 are trans- .mitted to the central station A through thedistributors 20 and 21 to control the supervisory lamps.
- Each of the distributors is arranged to have its brush arm stopped once per revolution and then released automatically due to the passage of the brush carried by the brush arm over the segments to which the release magnet of the other distributor is connected, thereby causing the brush arm thereof to be released.
- the brush arm of each of the distributors is arrested periodically and subsequently released by the other distributor located at the same station, thus providing a continuously operating system.
- relays 14 and 15 at station B are also in the position shown be open. -When it is desired to operate.
- switch 8 is moved to engage its upper contact whereby the negative source of current is connected to segment 51 of distributor 12.
- the distributor brush in passing over segment 51 causes the transmission of a correspondinggimpulse to station E a relay over the line conductor upon being received at station B is caused to flow, upon the passage of the brush of distributor 13 over segment 52, through the windings of relay 14.
- the passage of a negative impulse through the windings of 14 causes the reversal of the armature thereof, thereby causing the completion of an energizing circuit for the operating magnet of power switch 1, extending from battery 54 through the Winding of the operating magnet of power switch 1 and contact 53 and armature of relay .14 to ground.
- Power switch 1 is then operated for bridging the terminals of the power circuit controlled thereby, as well as causing the opening ofswitch 16 and the closure of its upper contact.
- the operation of switch 16 in this manner establishes an energizing circuit for relay 23 at station A upon the passage of the brush of distributor 20 over segment 55 and the passage of the brush of distributor 21 over segment 56 to which .the windingsxof relay 23 are serially connected.
- the impulse traversing'the windings of relay 23 for. the condition just described being of a negative polarity causes the reversal of the armature of relay 23 for breaking the local circuit of lamp 3, and establishing a circuit for lamp 4, which indicates that the power switch l'has been closed.
- the operation of the power switch 2 and other similar power switches associated with other segments of the distributors is similar to the operation of power switch 1.
- the successive operation of the two sets of distributors is accomplished by successively energizing the release magnets of one set through circuits established by the other set.
- the circuit for releasing the distributors 12 and 13 is as follows: from the source of currentlO. conductors 24 and 25, release magnet 39 of distributor 12, conductor 26, segment of distributor 21. through the brush arm. segment 40, conductor 27, segment 28, brush arm and collector ring 41 of distributor 12, conductor 29,'line 7, collector ring 47, brush arm and segment 36 of distributor 20.
- Switch 1 is shown as a simpleelectrically operated power switch.
- Switch 2 is shown as a power switch equipped with underload and overload release relays 49 and 50 respectively. It will be noted that should switch 2 be automatically released due to relays 49 or 50,,such release will be immediately indicated by the illumination of lamp 5. "When it is desired to discontinue the operation of the system, the switch 57 may be opened for disabling the energizing circuit of release magnet v39 of distributor 12, whereupon the brush arm of distributor 12 after completing its cycle of rotation will be stopped until the subsequent closure of switch 57. Likewise the other distributors will be stopped.
- a central controlling station and a remote station, a plurality of electromagnetically controlled switches at the remote station, a supervisory device .corresponding to each switch and located atthe central station, a rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectively to the switches, a rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectively to the supervisory devices from the switches, and holding and re-' leasing means for each distributor, transmitter and receiver, such holding and releasing means for each set cally in series, and said means for one se being controlled by the other set.
- a central station In a system forremote control and supervision, a central station, a remote station, a plurality of electromagmeticv devices having normal. an alternate positions at said remote station, a pair of signaling indicators at the central station for indicating the two positions of each of said devices, a key at the central station for each of said devices having two positions, a single conductor interconnecting said stations, a pair of transmlttmg and recelvmg dlstrlbutors at each station, said keys in one position applying one electrical condition to the transmitting distributor segments and in the other position applying another electrical condition, relays at the remote station controlling the position of said devices operated by the receiving distributor in accordance 'with the positions of the actuated keys at the central station, switches operated by the actuated devices to apply different electrical conditions to the transmitting distributor segments at the remote stations,relays at the central station operated by the receiving distributor thereat in accordance with the devices actuated at the remote station, and means actuated by thetran'smitting and receiving
- a central station In a system for remote control and supervision, a central station, a remote station,
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Remote Monitoring And Control Of Power-Distribution Networks (AREA)
Description
Nov- 17, 1925- J. C. FIELD SUPERVISORY SYSTEM Filed Oct. 18. 1 921 Owns/7hr.-
I l/osepfi 677%.
Patented Nov. 17, v 1925.
UNITED STATES PATENT OFFICE.
JOSEPH C. FIELD, OF- ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N.'Y., A CORPORATION OF NEW YORK.
SUPERVISORY SYSTEM.
useful Improvements in Supervisory Systems, of which the following is a full, clear, concise, and exact description.
This invention relates to control and s11- pervisory systems, and particularly to such,
systems in which switches or other'apparatus may be remotely controlled and supervised.
The invention is particularly adapted for use in connection with circuit controlling apparatus employed on power lines where it is desired to control a number of distant circuits from a central station.
An object of the invention is to provide a system of this character which includes a minimum number of operating elements, and which is reliable and rapid in operation.
' Another object of the invention is to provide means for indicating at the central station the condition of the apparatus at a remote station.
In this system there are a central or controlling station and a remote station in or near which the apparatus tobe controlled is situated. Each of these stations is provided I with a transmitting and a receiving rotary distributor such as is commonly used in printing telegraph systems. These distributors may be of the type disclosed in Patent No. 1,311,915 granted to P. M. Rainey, Au-
gust 5, 1919. The receiving distributor at each station operates synchronously with the transmitting distributor at the other station, the brush arm of each of the distributors, which is frictionally mounted on a continuously rotating shaft being adapted t'o be arrested periodically and then released automatically throdgh the instrumentalitiy of the other distributor. The transmitting distributor at the control station transmits controlling impulses which are selectively distributed by the corresponding receiving distributor to electromagnetic devices through which the desired switch controlling or other remote operation is performed. At the remote station the controlled apparatus mechanically operates switches which supply current to be transmitted in impulses by "the transmitting distributpr at the remote sta- Application filed October 18, 1921. Serial No. 508,443.
tion, which impulses are selectively distributed by the receiving distributor at the control station to electromagnetic devices, through which signals are operated indicating the condition of the apparatus at the remote station. The system may be considered as having two parts. One part transmits impulses to the mechanism to be controlled, and the other part transmits impulses generated at the controlled mechanism to operate the supervisory apparatus at the central station.
Another object of the invention is to provide means for repeating the controlling impulses at regular intervals, so that if the controlling means does not immediately operate at the local station, succeeding 1 mpulses will insure its operation if such is possible and with little delay.
Another feature of the invention is the manner in which synchronism is secured between the transmitting and receiving distributors of each set. As has been said, the distributors are in two pairs. These pairs do not operate simultaneously but successively. tion of one set of distributor arms, they are locked, and, as they near the completion of a revolution, release the other set of distributor arms which go through a similar cycle of operations to release the first set. This operation is continually repeated.
Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawing which shows diagrammatically one embodiment of the invention.
Referring to the drawing, the central station from which A rep-resents it is desired 'to control a series of electrically operated devices at a remote station B. The electrically operated devices disclosed here consist of'power switches of-which 1 and 2 are That is to say, after a full revolu- At station A there is provided a plurality of manually operated controlling switches of which 8 and 9 are typical, and which correspondto the power switches 1 and 2, re-
I spectively.
Two sources of current 10 and 11 having opposite poles grounded are each associated with the switches 8 and 9 in such a manner that the moving element of these switches may be connected with negative or positive current by operating them in opposite directions. The moving elements of switches 8 1 and. 9 are associated with se ner hereinafter described, is operated in synchronism with the transmitter 12. Im: pulses from the line 7 are transmitted to polarized relays 14 and 15 which correspond to the switches 8 and 9 and the power switches 1 and 2 respectively, through the collector ring 42, brush arm and segments of a receiving distributor 13. The polarized re lay 14 operates to energize or deenergize the electromagnet of .the power switch 1 to open or close it, depending upon the polarity of the current impulse transmitted to the polarized relay. Likewise the polarized relay 15 operates or releases .power switch 2, depending upon the polarity of the impulses transmitted thereto.
Power switches 1' and2 are provided with mechanically operated switches 16 and 17 which have alternate contacts connected to sources of current 18 and 19 of opposite polarity. The power switches are mechanically connected with the moving elements of these switches 16 and 17 so that when the power switches open or close they cause switches 16 and 17 to connect with current of one or theother polarity.
The moving elements of the switches 17 and '16 areelectrically connected to successive segments of a rotary transmitting distributor 20 through the brush arm and collector ring 47 of which electrical connection ismade with the line 7.
A corresponding rotary receiving distributor 21 is located at the central station A and is connected through its collector ring 49 and brush arm to the line 7. - Polarized relays 22 and, 23 are connected to successive segments of the receiver 21 so that the impulses transmitted from the sources of current 18 and 19, through the switches 16 and 17 are transmitted to the polarized relays 22 and 23, respectively. It
will be evident that additional power 'switches, such as 1 and 2, may be connected in the circuit, "in which case, corresponding polarlzed relays such as 14, 15 and '22, 23, control switches, such as 8 and 9', and
switches-such as 16 and 17, will be associated with corresponding segments of dis- I tributors 13, 21,12 and 20, respectively, lead wires being shown for this purpose.
v \Vhen the power switch 1 is in its open positioh, as shown in the drawing, positive current is transmitted through the segment' 55.0f' the distributor 2O asthe brush arm thereof revolves, through the line 7, through \the collector ring 49 and brush arm of re-- thus lighting the lamp and showing that the power switch 1 is open.
When the power switch 1 is closed, negative current-is supplied from the battery 19 in a manner, similar to that before described, to operate the polarized relay 23 in its opposite direction, thus illuminating the lamp 4 and indicating at the station A that the power switch 1 is in its closed position. Similar circuits are established for the lamps 5 and 6 by the power switch 2.
As above described, the system comprises twoparts, one by means of which impulses are transmitted from the central station through the distributors 12 and 13 to the power switches at station B, and the other by means of which impulsesunder the control of the power switches 1 and 2 are trans- .mitted to the central station A through thedistributors 20 and 21 to control the supervisory lamps.- Each of the distributors is arranged to have its brush arm stopped once per revolution and then released automatically due to the passage of the brush carried by the brush arm over the segments to which the release magnet of the other distributor is connected, thereby causing the brush arm thereof to be released. I In the normal operation of the system, the brush arm of each of the distributors is arrested periodically and subsequently released by the other distributor located at the same station, thus providing a continuously operating system.
With the switches 8 and 9 in the position shown in the drawing, relays 14 and 15 at station B are also in the position shown be open. -When it is desired to operate.
either of these switches 1 and 2, it is necessary to actuate the corresponding switch 8 'or 9 for connecting the negative source-of current 11 with the segment of the distributor allotted to, this particular switch.
For instance, should it be desired to close 'switch 1,. switch 8 is moved to engage its upper contact whereby the negative source of current is connected to segment 51 of distributor 12. The distributor brush in passing over segment 51, causes the transmission of a correspondinggimpulse to station E a relay over the line conductor upon being received at station B is caused to flow, upon the passage of the brush of distributor 13 over segment 52, through the windings of relay 14. The passage of a negative impulse through the windings of 14, causes the reversal of the armature thereof, thereby causing the completion of an energizing circuit for the operating magnet of power switch 1, extending from battery 54 through the Winding of the operating magnet of power switch 1 and contact 53 and armature of relay .14 to ground. Power switch 1 is then operated for bridging the terminals of the power circuit controlled thereby, as well as causing the opening ofswitch 16 and the closure of its upper contact. The operation of switch 16 in this manner establishes an energizing circuit for relay 23 at station A upon the passage of the brush of distributor 20 over segment 55 and the passage of the brush of distributor 21 over segment 56 to which .the windingsxof relay 23 are serially connected. The impulse traversing'the windings of relay 23 for. the condition just described being of a negative polarity, causes the reversal of the armature of relay 23 for breaking the local circuit of lamp 3, and establishing a circuit for lamp 4, which indicates that the power switch l'has been closed. The operation of the power switch 2 and other similar power switches associated with other segments of the distributors is similar to the operation of power switch 1.
. It is necessary that these two parts of the system be operated successively and not simultaneously, in order to avoid a confusion of the impulses onthe line 7. The successive operation of the two sets of distributors is accomplished by successively energizing the release magnets of one set through circuits established by the other set. The circuit for releasing the distributors 12 and 13 is as follows: from the source of currentlO. conductors 24 and 25, release magnet 39 of distributor 12, conductor 26, segment of distributor 21. through the brush arm. segment 40, conductor 27, segment 28, brush arm and collector ring 41 of distributor 12, conductor 29,'line 7, collector ring 47, brush arm and segment 36 of distributor 20. conductor 30, segment 43, brush arm and segment of distributor 13, winding of release magnet to, nets 39 and 45 are energizedin series, releasing distributors 12 and 13 simultaneously which make one revolution. Just before completion of this revolution, the brush arms contact with segments 31 and 32 respectively establishing a circuit from source 7. This impulse,
ground. Release mag- I of current 10, conduct0r 24, through the re-.
lease magnet 46 of distributor 21, conductor 33, segment 31, brush arm andcollector ring 41 of disributor 12, conductor 29, line 7 to the collector ring 42 of distributor '13, brush arm, and segment 32 of distributor 13, re-
will operate subsequently.
Switch 1 is shown as a simpleelectrically operated power switch. "Switch 2 is shown as a power switch equipped with underload and overload release relays 49 and 50 respectively. It will be noted that should switch 2 be automatically released due to relays 49 or 50,,such release will be immediately indicated by the illumination of lamp 5. "When it is desired to discontinue the operation of the system, the switch 57 may be opened for disabling the energizing circuit of release magnet v39 of distributor 12, whereupon the brush arm of distributor 12 after completing its cycle of rotation will be stopped until the subsequent closure of switch 57. Likewise the other distributors will be stopped.
\ What is claimed is:
1. In a system for remote control and supervision, a central controlling station" and a remote station, a plurality of electromagnetically controlled switches at the remote station, a supervisory device .corresponding to each switch and located atthe central station, a rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectively to the switches, a rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectively to the supervisory devices from the switches, and holding and re-' leasing means for each distributor, transmitter and receiver, such holding and releasing means for each set cally in series, and said means for one se being controlled by the other set.
2. In a system for remote control and 511-1 pervisiom'a central controlling station and a remote station, a line associating the stations, a plurality of electroma'gnetically conswitch and located at the central-station, a
operate on the first being connected electria relay which may have failed to operate 'lao ' rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectivelyto the switches, a rotary distributor set comprising a transmitter and a receiver to transmit electrical impulses selectively to the supervisory devices from the '-switches, and electromagnetically operated holding and releasing means for each distributor, transmitter and receiver, such means for each set being connected electrically in series, and said means for one-set I being controlled by the other set.
3. In a system forremote control and supervision, a central station, a remote station, a plurality of electromagmeticv devices having normal. an alternate positions at said remote station, a pair of signaling indicators at the central station for indicating the two positions of each of said devices, a key at the central station for each of said devices having two positions, a single conductor interconnecting said stations, a pair of transmlttmg and recelvmg dlstrlbutors at each station, said keys in one position applying one electrical condition to the transmitting distributor segments and in the other position applying another electrical condition, relays at the remote station controlling the position of said devices operated by the receiving distributor in accordance 'with the positions of the actuated keys at the central station, switches operated by the actuated devices to apply different electrical conditions to the transmitting distributor segments at the remote stations,relays at the central station operated by the receiving distributor thereat in accordance with the devices actuated at the remote station, and means actuated by thetran'smitting and receiving distributors near the end of their travel for starting the other pail- 0f distential to the transmitting distributor at the central station depending upon the position of said keys, polarized relays at the remote station controlling'the position of said devices operated through the receiving distributor in accordance with the polarity of the potential applied to, said transmitting distributor by said keys, switches operated by the actuated'devices to apply positive or negative potential tothe transmitting distributor at the remote station, polarized relays at the central statioh operated by the receiving distributor thereat in accordance with the devices actuated at the remote station, and release magnets actuated by the transmitting and receiving distributors near the end of each revolution for starting the other pair of distributors.
5. In a system for remote control and supervision, a central station, a remote station,
tor joining said stations and the receiving J distributor at the remote station, switches operated by the actuated devices, polarized relays at the central station for controlling the lighting of said signaling lamps, said switches applying positive or negative potential to said polarized relays through the transmitting distributor at the remote station, the conductor joining said stations and the receiving, distributor at the central station,-and means controlled by the transmitting and receiving distributors near the end of each revolution for starting the other pair of distributors. i
In witness whereof, I hereunto subscribe mylname this 11th day of October A. D., 192
JOSEPH o. FIELD.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US508443A US1562211A (en) | 1921-10-18 | 1921-10-18 | Supervisory system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US508443A US1562211A (en) | 1921-10-18 | 1921-10-18 | Supervisory system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US1562211A true US1562211A (en) | 1925-11-17 |
Family
ID=24022770
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US508443A Expired - Lifetime US1562211A (en) | 1921-10-18 | 1921-10-18 | Supervisory system |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US1562211A (en) |
-
1921
- 1921-10-18 US US508443A patent/US1562211A/en not_active Expired - Lifetime
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US1689294A (en) | Remote control and indicating system | |
| US2116372A (en) | Signal transmitter | |
| US1632106A (en) | Signaling system | |
| US2303918A (en) | Impulse transmission | |
| US1562211A (en) | Supervisory system | |
| US1945665A (en) | Supervisory control system | |
| US2262458A (en) | Electrical signaling or control system | |
| US2123220A (en) | Alternating current signaling system | |
| US1616186A (en) | Control and supervisory system | |
| US2109273A (en) | Noninterfering successive signaling system | |
| US1378943A (en) | Selective signaling system | |
| US2248583A (en) | Code translating mechanism | |
| US1747821A (en) | Supervisory system | |
| US1771234A (en) | Selective signaling system | |
| US1562210A (en) | Signaling system | |
| US1762971A (en) | Remote-control power system | |
| US1371748A (en) | High-capacity selective signaling system | |
| US1744220A (en) | Supervisory control system | |
| US981997A (en) | Signal-telegraph. | |
| US1562188A (en) | Selecting system | |
| US1464090A (en) | Signaling system | |
| US1863089A (en) | Remote control system | |
| US1324798A (en) | Signaling system | |
| US1221177A (en) | Selectively-operated system. | |
| US285342A (en) | Signaling apparatus foe telephone exchange systems |