GB1456526A - Monitor system - Google Patents

Abstract

1456526 Data processing EBASCO SERVICES Inc 19 Nov 1973 [22 Nov 1972] 53694/73 Heading G4A To provide a log of data, information from a plurality of devices at various pick-up points is stored, in a store affording a format having provision for a number of logs each having a number of positions of which a portion is reserved for data corresponding to different input variables, each input variable being assigned a name (which is used together with any desired suffixes by an operator or a program to access the data), the data when it is retrieved being presented on output log pages having a preassigned format (Fig. 2, not shown) (e.g. comprising a log page identification, a log page heading for defining a plurality of variables and a plurality of lines for listing the data under its appropriate log page heading). As described, each item of data has a basic name of the form PNNNN where P is a prefix specifying, e.g., analogue input, constant and NNNN is a number from 0-9999, each incoming item of data having assigned to it its name, a time and a quality (one of four levels 0-3). A log may be in any one of four states: (1) free log state 0 representing the log number without names and page assignment, (2) log state 1 including names, (3) log states 2 (active but not printing) including names and values at specified time intervals and (4) log state 3 (outputting) including names and values and printing out the data. In the active state the logging system collects the values associated with the logs at a time assigned to the log and stores them in memory (drum/disc) with overwriting of the oldest line so that a full page of log is held ready for printing. The frequency of printing may be specified by the operator and the operator may request printing of any log by keying in the appropriate information. As well as tabular data, graphic representations of variables may be provided using a log trend CRT display, generally when the data is changing rapidly and has just gone into an alarm state. Each log has an associated trigger which when activated changes the log states to the next state, e.g. active state to printing state. An alarm may be given at fixed changes, delta, of an input variable for example when the temperature of a boiler changes by 5‹ F. when the temperature is outside normal upper and lower limits. A multiplier factor may be selected to change the effective value of delta to give more weight to some variables. When a fault occurs, since an erroneous allocation of the fault may be given due to the different delay time before trip actuators operate their contacts, a control unit (300, Fig. 10, not shown) includes a store (302) for storing the time delay characteristics of each protective device so that it may provide at its output (312) a signal indicating the device had failed. The alarm information is outputted on the CRT display in the first three lines starting from the bottom, the first alarm for a variable occupying the whole screen whereas a reduced format is used when the operator acknowledges the alarm. When the screen is filled the oldest alarm messages are transferred to memory to allow compacting downwards. A "believed value" tuning circuit provides a believed value signal for a variable derived by keeping, e.g. 2 out of 3 related output variables constant whilst a third variable sweeps linearly through its expected range. A flow drawing for deriving the believed value is given (Fig. 16, not shown).