Method for processing analog output signals from current and voltage transducers and facility for carrying out the method

• US 4,725,838 A
• Filed: 03/25/1985
• Issued: 02/16/1988
• Est. Priority Date: 03/26/1984
• Status: Expired due to Term

• Current Assignee: BBC Brown Boveri & Company Limited (ABB Limited)
• Original Assignee: BBC Brown Boveri & Company Limited (ABB Limited)
• Inventors: Maschek, Martin, Mastner, Georg
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/715,467
• Time in Patent Office: 1,058 Days
• Field of Search: 340/870.19, 340/870.24, 340/870.29, 370/96, 370/113, 370/91, 370/81, 370/41, 328/151
• US Class Current: 340/870.19
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• CPC Class Codes: G01R 21/133 by using digital technique

Abstract

Analog output signals from decentralized transducers for current and voltage are sampled with timing patterns generated at a decentralized location and are transmitted to a central evaluating facility in the form of digitally encoded data streams (D_UR, . . . ).

For the purpose of generating data sets which are each based on one sampling of each analog output signal, such that the relative time displacement of the samplings should not exceed a predetermined value which corresponds to the maximum (Δ) of the data-refresh intervals, latch commands (L) are generated at greater intervals in the central evaluating facility, following which in each case the digitized sampled value arriving next of each data stream (D_UR, . . . ) is temporarily stored. After the temporary storage has taken place, in each case a "Ready" signal (B_UR, . . . ) is set. The "Ready" signals (B_UR, . . . ) are combined in a logical AND operation to form a "Data set ready" signal (DB) which is transferred to a computer which interrogates the temporarily stored data (Z_UR, . . . ) via a databus.

Claims

1. A method for processing, in a central evaluating facility, analog output signals from a plurality of decentralized transducers, comprising the steps of:

generating a timing pattern at a decentralized location corresponding to the decentralized transducers in accordance with data-refresh intervals;

sampling an analog output of each decentralized transducer in accordance with said timing pattern to obtain a sampled value;

transmitting said sampled value of said analog output of each decentralized transducer directly to said central evaluating facility in the form of a data stream of successive digitized sampled values; and

producing data sets at the central evaluating facility which contain one digitized sampled value from each data stream, said data sets being produced by the substeps of;

generating latch commands at the central evaluating facility at intervals that are at least as great as the maximum data-refresh interval; and

acquiring, after each latch command, the digitized sampled value of each data stream that is present, or if not present, the next arriving sampled value of each data stream.

2. Method according to claim 1, wherein the maximum data-refresh interval of the timing pattern generated at the decentralized location is less than 2000 μ

sec and preferably less than 5 μ

sec.

3. A method according to claim 1 and further comprising, after each acquisition of a digitized sampled value from a data stream, the steps of setting a READY signal for each digitized sampled value which is acquired following a latch command and generating a DATA SET READY signal by performing a logical AND operation on said READY signals once a data set has been generated.

4. An apparatus according to claim 3, wherein the central evaluating facility further includes a databus which is connected to the computer and to the temporary memories.

5. An apparatus according to claim 4, wherein the central evaluating facility further includes at least one D/A converter operatively connected with said receiver/converter for converting said parallel digital data into an analog signal.

7. The method of claim 1, wherein said latch commands are generated at intervals that are greater than the maximum data-refresh interval.

6. An apparatus for processing a plurality of analog output signals, comprising:

a plurality of decentralized converter/transmitters,

a central evaluating facility, each of said converter/transmitters having a corresponding potential-isolating data line connected with said central evaluating facility;

each of said decentralized converter/transmitters including means for generating data-refresh intervals and an A/D converter for sampling one of said analog output signals during each data-refresh interval and converting said sampled analog output signal into a serial data stream of successive sampled values for transmission over the corresponding one of said data line to said central unit, each of said data-refresh interval generating means operating independently with respect to said central evaluating facility;

said central evaluating facility including a receiver/converter for each converter/transmitter for converting each serial data stream into parallel digital data, a temporary memory operatively connected to each receiver/converter for temporarily storing said parallel digital data, a control unit for generating latch commands at intervals at least as great as the maximum data-refresh interval, said latch command causing each of said temporary memories to store the next successive sampled value from the respective receiver/converter, and a computer for interrogating the digital sampled values stored in the temporary memories.

8. The apparatus of claim 6, wherein said latch commands are generated at intervals that are greater than the maximum data-refresh interval.