JP2772984B2 - Process volume monitoring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a process amount monitoring device that monitors a change in a process amount and issues an alarm.

<Prior Art> Monitoring process amounts such as temperature and pressure in process control is important from the viewpoint of proper control of a process and safety. In order to monitor such a process amount, it is necessary to process and display a change in the process amount by an appropriate method. Such a processing and display method are shown in FIGS. FIG. 3A is a display example of an instantaneous value. The process volume is displayed as the length of the bar graph. (B) is a display of the change history,
A line graph is shown with the time on the horizontal axis and the magnitude of the process amount on the vertical axis. (C) is a histogram,
Average value and distribution of process volume can be easily grasped. 4th
FIG. 7A is a scatter diagram, which is convenient for grasping the correlation between two process quantities. (B) is an X / R chart,
The time change of the deviation from the average value is shown. This is convenient for grasping whether the process amount is managed, and has the advantage that the occurrence of a nonstandard process amount can be grasped at a glance. These processes and display methods are appropriately selected according to the purpose, and are used for monitoring a process amount.

<Problems to be Solved by the Invention> However, any of these monitoring methods or display methods may cause malfunctions when applied to a process amount including noise, so that reliable monitoring can be performed. There was a problem that there was not.

<Object of the Invention> An object of the present invention is to provide a process amount monitoring apparatus capable of appropriately monitoring a process amount including noise by simple processing.

<Means for Solving the Problems> The present invention for solving the above problems includes a sampling means 10 for sampling a process amount at regular intervals, and a first process from a sampled process amount in a first monitoring area. First representative value extracting means 12 for calculating the distribution of the amount, and calculating the distribution of the second process amount from the sampled process amount in the second monitoring area defined to be larger than the first monitoring area. When the difference between the distribution of the first and second process amounts becomes larger than the alarm set value which is larger than the distribution of the change in the process amount due to disturbance, And an alarm means 15 for outputting an alarm.

<Operation> The alarm unit outputs an alarm when the difference between the distributions of the first and second process amounts becomes larger than the alarm set value. here,
Even if the process volume responds to the disturbance, if the process volume returns to the original state immediately after the disturbance disappears, the process will not be adversely affected. It is set larger than the distribution to reduce false alarms.

FIG. 1 shows the configuration of an apparatus for realizing a process amount monitoring apparatus according to the present invention. In FIG. 1, reference numeral 10 denotes a sampling means, which turns on a switch 11 at regular intervals to sample a process amount. A process amount is applied to one end of the switch 11. Reference numeral 2 denotes a representative value extracting means, to which a process amount sampled by the switch 11 is input, and which calculates a representative value from the sampled process amount in the first monitoring area. Numeral 13 denotes a representative value extracting means, to which the process amount sampled by the switch 11 is input, and which calculates the representative value from the sampled process amount in the second monitoring area larger than the first monitoring area. The calculation of these representative values is performed at regular intervals, and the output is updated. A display means 14 displays the representative values calculated by the representative value extracting means 12 and 13 so that the difference can be recognized. For example, the distribution of the process amount is taken as a representative value, and the distributions calculated by the two representative value extracting means 12 and 13 are displayed in different colors and superimposed.
Reference numeral 15 denotes an alarm means, which receives the output of the representative value extracting means 12 and 13 and the alarm set value, and compares the difference between the two representative values or a predetermined function value with the alarm set value to obtain the difference or function value. When is larger than the alarm set value, an alarm is output externally.

FIG. 2 shows a specific example. FIG. 2 (A) shows the variation of the process amount in the steady state, where 16 is the process amount and 17 is the set value. The process amount shows small fluctuation around the set value. t ₀ is the present, and the left direction is the past. 18 distribution diagram of a process amount in the first monitored zone X ₁ representative value extracting unit 12 calculates (histogram), 19 of the process amount in the monitored area X ₂ long second from the monitoring zone X ₁ of the first FIG. 9 is a distribution diagram calculated by a representative value extracting unit 13. The hatched portion indicates the difference, and is displayed by the display unit 14. (B) is a case where the process amount responds to a disturbance in the same state as (A). Due to disturbance, the process amount fluctuates greatly as shown in FIG. The first surveillance zone X ₁ and the second process variable in the monitoring zone X ₂ distribution diagram 21 in this case is different than the distribution diagram 18, 19 (A). However, the difference (shaded area) between these distribution diagrams 21 and 22 is almost the same as (A). A change in the process amount due to a disturbance such as 20 normally occurs, and the state returns to the original state immediately after the disturbance disappears. Therefore, no alarm should be issued as it will not adversely affect the process. An alarm may be issued simply by monitoring the change in the process amount. In such a case, if an alarm set value is set so that the alarm is not issued, there is a risk that the alarm may be overlooked when the alarm should be issued. In the method of monitoring the difference between the distribution maps as in the present embodiment, no difference occurs due to a change in the process amount due to a disturbance. Therefore, even if the alarm set value is reduced, there is no possibility that a false alarm is issued. (C) set value 17 at time t ₁ is representing a case in which changes abrupt change manner. The first monitoring section and X ₁ process of distribution diagram 23 in very different distribution diagram 24 of a process amount in the second surveillance area X ₂ cases, and also increases the difference. Therefore, the warning means 15 issues a warning to the outside. When an alarm is issued, it is determined whether or not the change is expected. If it is not expected, appropriate measures such as investigation of the cause are taken.

In this embodiment, the display of the representative value and the alarm output are performed at the same time. However, only one of the display and the alarm output may be performed.

In the embodiment, the difference between the representative value and the alarm set value is compared. However, the function value F (x ₁ , x _{2) using} the representative values x ₁ and x ₂ of the first and second monitoring areas as variables. ) May be compared with the alarm set value.

<Effects of the Invention> As described above in detail with reference to the embodiment, in the present invention, a distribution device of a process amount in two monitoring areas having different sizes is calculated, and a method capable of comparing these distribution devices is used. The warning is displayed by comparing the difference or the function value with the alarm set value. Therefore, a warning is not output for a change in the process amount due to a disturbance that does not affect the process, so that a more reliable warning can be obtained.

In addition, by appropriately selecting the size of the first and second monitoring areas and the alarm set value, the first monitoring area may be changed depending on the period of the disturbance.
, But not in the representative value of the second monitoring area. Therefore, by adjusting the size of the monitoring area and the alarm set value, the type of disturbance to be detected can be selected.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus for realizing a method of monitoring a process amount according to the present invention, FIG. 2 is a diagram showing a relationship between a change in a process amount and a representative value, and FIGS. It is a figure showing a display method for monitoring a process quantity. 10 ... sampling means, 12, 13 ... representative value extraction means, 1
4 ... Display means, 15 ... Alarm means.

Claims (1)

(57) [Claims] 1. A sampling means (10) for sampling a process amount at regular intervals, and a first representative value extraction for calculating a distribution of a first process amount from a sampled process amount in a first monitoring area. Means (12) and second representative value extracting means (13) for calculating the distribution of the second process quantity from the sampled process quantity in the second monitored area larger than the first monitored area. And alarm means for outputting an alarm when the difference between the distributions of the first and second process amounts is larger than an alarm set value which is largely determined as compared with the distribution of the change in the process amount due to disturbance ( 15) A process quantity monitoring device, comprising: