Sequence of events recorder and system for transmitting sequence data from a remote station to a master station

• US 4,057,785 A
• Filed: 03/14/1975
• Issued: 11/08/1977
• Est. Priority Date: 03/14/1975
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Onufer, Joseph R., Furniss, William E., Vancsa, George I.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/558,513
• Time in Patent Office: 970 Days
• Field of Search: 340/163, 340/147 R, 340/408, 340/409, 340/152 R, 340/413, 340/172.5, 340/151
• US Class Current: 340/870.15
• CPC Class Codes: H02J 13/00012 using an auxiliary transmission line
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/16 Electric power substations

Abstract

Apparatus for detecting and recording status changes of two-state devices in a power network substation, a pipeline substation, or the like. At a substation a remote terminal unit records status changes in its digital memory. When a sequence of status changes occurs, each change is recorded, together with its time of occurrence as measured from the time of occurrence of the first change, thereby reducing the size of memory for recording sequence data. Upon request, data related to a sequence of changes is transmitted to a master station in chronological order of the changes, to simplify processing of such data at the master station. Provision is made to permit the master station to convert elapsed time to real time, and to reduce the time required of the master station to retrieve sequence data from a remote terminal.

Claims

1. System apparatus for detecting and recording a time sequence of status changes of a plurality of two-state devices at each of a plurality of locations, said apparatus comprising:

a remote terminal unit for each of the locations,

means for processing and recording data at a master station in response to data signals received from said remote terminals,

means for transmitting data signals between said remote terminals and said master station under predetermined control conditions,

each of said terminals including first means for periodically detecting the state of each device associated therewith,

second means for comparing the currently detected state of each associated device with the previously detected state of the associated device to detect a difference between such state,

third means for storing the identity and the currently detected state of an associated device when such state differs from the previously detected state, and for storing a representation of the elapsed time at which the difference is detected relative to a reference time point, and

said master station means including means for recording absolute time to enable correlation of transmitted elapsed time data from said remote terminals.

2. Apparatus according to claim 1 wherein each remote terminal unit is associated with a power system substation.

3. Apparatus according to claim 1 wherein the two-state devices at each remote terminal are grouped, each group having a predetermined number of the devices, and the states of the devices in a group are detected simultaneously.

4. Apparatus according to claim 3, wherein said third means includes means for representing the detected states of the devices of a group by a detected status word, such word having a number of bits equal to the number of devices in the group, each of which bits represents the detected state of a corresponding one of the devices of the group.

5. Apparatus according to claim 4 wherein there is a plurality of device groups with each device group having a corresponding group address.

6. Apparatus according to claim 5 wherein said third means includes means for detecting the states of the devices a group at a time.

7. Apparatus according to claim 4 wherein said third means includes means for holding a detected status word in a temporary storage location and means for comparing the detected status word with a stored previously detected status word corresponding to the addressed device group.

8. Apparatus according to claim 1 wherein the elapsed time at each terminal is measured from the time of detection of the first change of state of a device associated with the terminal.

14. Apparatus according to claim 7 wherein said means for comparing at each terminal also generates a momentary change word associated with a detected status word to indicate which bits of the status word differ from the corresponding bits of the previously detected status word, and said third means stores the momentary change word associated with a stored detected status word.

15. Apparatus according to claim 14 wherein data relating to detected changes of state are stored at successive storage locations at each terminal, in the chronological order with which the status changes are detected.

16. Apparatus according to claim 15 wherein event data is transmitted from successive storage locations of each terminal beginning with a preselected location, whereby event data is received by the master station in the chronological order with which the events were detected.

17. Apparatus according to claim 8 wherein said second means at each terminal generates a change of status signal upon detection of the first change of status, and means are provided for transmitting the generated change of status signal to the master station to correlate elapsed time data at remote locations with absolute time at the master station.

18. Apparatus according to claim 17 wherein said master station means includes, means responsive to a received change of status signal for storing a representation of absolute time upon receipt of the change of status signal.

19. Apparatus according to claim 17 wherein said second means at each terminal generates a sequence of events signal upon detection of a second event, the generated sequence of events signal being subsequently transmitted to said master station means to indicate that a sequence of at least two status changes has been detected by said second means.

20. Apparatus according to claim 19 wherein said master station means is responsive to a received sequence of events signal to repeatedly request the sending terminal to transmit data from storage to said master station means, the sending terminal having means responsive to the first request to transmit event data stored at a predetermined number of successive locations beginning with a preselected location, and the sending terminal having means responsive to each request subsequent to the first request to transmit event data stored at the predetermined number of locations immediately succeeding those locations from which event data was previously transmitted, until no further request is made by said master station means.

21. Apparatus according to claim 20 wherein said master station means checks the data that is stored in each of the predetermined number of storage locations upon receipt of such data, said master station means ceasing to request further event data when the last received data contains at least one zero.

22. Apparatus according to claim 21 wherein said master station means generates a clear memory signal upon detection of the first received data which contains at least one zero, the clear memory signal subsequently being transmitted to said second means to notify said second means to store zeros at those location of said storage means that are utilized for storage of event data.

9. Apparatus for detecting and recording status changes of a plurality of two-state devices, wherein each device is a member of a respective device group having a unique address and including a predetermined number of devices, comprising:

means for periodically detecting the states of the devices of each group, wherein the detected states are represented by a detected status word having a bit corresponding to each device of the group,

storage means for recording a previously detected status word corresponding to each group of devices,

means for comparing each detected status word representing the currently detected states of the devices of a group with the corresponding detected status word in said storage means to detect a difference between such words, and

means for storing the detected status word representing the currently detected status of the devices of a group in storage means when a difference is detected.

10. Apparatus according to claim 9 wherein the states of the devices are detected one group at a time in succession, and a detected status word representing the currently detected states of a group of devices is stored at a temporary storage location included in said storage means until the states of the devices in the succeeding group are detected.

11. Apparatus according to claim 9 wherein said means for comparing further generates a momentary change word associated with each detected status word that is recorded in said storage means, such momentary change word indicating those bits of the associated detected status word which differ from the corresponding bits of the previously detected status word, and said means for storing stores each momentary change word in said storage means.

12. Apparatus according to claim 11 wherein said storage means includes first and second preselected locations associated with each group of devices, a detected status word being recorded at the first location, and the associated momentary change word being recorded at the second location.

13. Apparatus according to claim 12 wherein said storage means further includes storage locations separate from the first and second locations associated with each device group, and upon occurrence of a detected change of state of at least one device of a group said means for storing records in such separate locations the address, the detected status word, and the momentary change word associated with the device group, with the elapsed time at which the change is detected relative to a reference point in time.