PATENT ABSTRACT
An alarm management system and method includes structure and function for receiving one or more process parameter signals representative of one or more process parameters. Each of the received process parameters is then compared with an associated alarm point. An alarm status signal is generated on the basis of the comparison. An annunciation command signal is transmitted on the basis of the alarm status signal. And, a sound is then generated on the basis of the annunciation command signal.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an alarm management system. More particularly, the invention relates to a system and method for managing alarms in an industrial facility. Even more particularly, the present invention relates to a system and method for managing a plurality of alarms in a nuclear power plant. 
     2. Description of Related Art 
     Day to day operations in most industrial facilities, including nuclear power generation plants, are typically uneventful. However, certain unscheduled events may occur that require the immediate attention of operational personnel. Thus, most process parameter monitoring systems are designed to include some type of warning system to alert operational personnel to an impending, or current, event requiring their attention. More specifically, these systems typically sound an audible alarm to alert operational personnel that a process parameter has exceeded a specified limit. 
     Some unscheduled events may result in numerous alarms being sounded. These alarms may come from different systems, require differing levels of attention, and require attention by different operational personnel. Thus, when multiple alarms sound simultaneously or in momentary succession, operational personnel must determine what system each alarm is associated with, the priority level of each alarm, and which operator is responsible for attending to each alarm. This may result in confusion, missed alarms, inattention to certain alarms, or a combination of all of these factors, especially if the alarms are spread out around the facility. 
     Designers have attempted to alleviate the above-mentioned factors to some extent in the nuclear power plant context. Specifically, modern nuclear power plants utilize a centralized control room design having computer-based workstations to allow convenient access to plant controls and functions from a single location. The workstations are divided into assigned operational responsibilities. For example, the reactor operator workstation encompasses controls and functions associated with reactor operations (e.g., primary plant systems including the nuclear reactor), and the turbine operator workstation encompasses controls and functions associated with secondary plant operations (e.g., steam plant systems). When one or more alarm situations occur, an alarm system outputs an audible tone to alert the control room operators. The system further causes the alarms to be depicted on workstation video display units as alarm lists, or highlighted on system mimic diagrams. The alarm lists may be filtered by certain categories such as by alarm priority or by the system in which the alarms occur. 
     However, even modem centralized control room designs exhibit certain deficiencies. Specifically, when an audible tone is generated upon occurrence of a new alarm, the operators must manually determine which operator has responsibility for the alarm. This is accomplished by manually scanning an alarm list to determine if the new alarm is associated with the reactor operator or the turbine operator. Or, the control room operators must examine the various system mimic diagrams on the video display units to make the determination. Both of these operations are time consuming and distracting. 
     Additionally, while the alarm lists may be filtered by certain categories, there is no coherent alarm status overview that allows an operator to conveniently observe the overall alarm-state of the plant and how the alarms are distributed. 
     An operator can readily determine individual alarms and groups of related alarms using the category filtering function, but it is difficult to ascertain the overall plant alarm-state and determine the distribution of the alarms. 
     Finally, present alarm systems provide no implementation that supports direct access to an operator&#39;s desired view of one or more alarms from a high-level plant alarm status overview. For example, an operator may wish to observe a new alarm from different perspectives, such as from an alarm list or from within a system mimic diagram to observe the context of the alarm relative to associated plant components and systems. With present alarm systems, an operator must either manually search through a display menu to select the desired system mimic diagram or manually recall an appropriate alarm list. 
     Thus, there is a need for an alarm annunciation system that notifies operators immediately, upon the occurrence of one or more alarms, which operator has responsibility for each alarm. There is also a need for an alarm distribution indication system that presents a coherent view of the current plant alarm-state and the distribution of alarms by operator responsibility, priority, and system. There is additionally a need for a device for selectively displaying alarms that supports direct access to an operator&#39;s desired view of one or more alarms from a high-level plant alarm status overview. Finally, there is a need for an entire alarm management system that incorporates each of these features. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, an alarm management system comprises receiving means, comparing and generating means, receiving and transmitting means, and sound generation means. The receiving means receives one or more process parameter signals representative of one or more process parameters. The comparing and generating means compares each of the received process parameter signals with an associated alarm setpoint and generates an alarm status signal on the basis of the comparison. The receiving and transmitting means receives the alarm status signal and transmits an annunciation command signal on the basis of the received alarm status signal. The sound generation means generates a sound on the basis of the annunciation command signal. 
     In another aspect of the present invention, an alarm annunciation system comprises receiving and transmitting means, tone generation means, and voice synthesization means. The receiving and transmitting means receives an alarm status signal and transmits an annunciation command signal on the basis of the received alarm status signal. The tone generation means generates a plurality of tones, each having a different frequency from another, on the basis of the annunciation command signal. The voice synthesization means synthesizes a human voice signal of a specified pitch on the basis of the annunciation command signal. 
     In still a further aspect of the present invention, an alarm distribution indication system comprises memory means, information extraction means, information categorization means, and display means. The memory means stores alarm information of a plurality of alarms. The information extraction means periodically extracts the alarm information from the memory means. The information categorization means categorizes the extracted alarm information into to a plurality of predetermined categories. The display means displays the alarm information, for each of the plurality of alarms, arranged into the plurality of predetermined categories. 
     In yet another aspect of the present invention, a device for selectively displaying a plurality of alarms, comprises a video display unit, an input selection device, information storage means, information categorization means, mimic display storage and generation means, and information transfer means. The information storage means stores alarm information for each of the plurality of alarms. The information categorization means periodically retrieves and categorizes the stored alarm information into a plurality of predetermined categories. The mimic display storage and generation means stores mimic display information for a plurality of process systems, and periodically retrieves the stored alarm information and generates the mimic display information for each of the plurality of process systems including the retrieved alarm information therein. The information transfer means receives a first command from the input selection device to select information and transfers the selected information to the video display unit for display thereon. The selected information includes one of the alarm information in one of the first plurality of predetermined categories, and the alarm information included in one of the plurality of process system mimic displays. 
     In yet still a further aspect of the present invention, a method of managing a plurality of alarms includes the steps of receiving, comparing, generating an alarm status signal, receiving the alarm status signal, transmitting an annunciation signal, and generating a sound. In the receiving step, one or more process parameter signals representative of one or more process parameters are received. In the comparing step, each of the received process parameter signals is compared with an associated alarm setpoint. In the alarm status signal generating step, an alarm status signal is generated on the basis of the comparison in the comparison step. The alarm status signal is received in the alarm status signal receiving step. An annunciation command signal is transmitted on the basis of the received alarm status signal, in the annunciation command signal transmission step. A sound is generated on the basis of the annunciation command signal, in the sound generation step. 
     The present invention provides distinct features and advantages over related alarm management systems and components. Specifically, an alarm annunciation system directs attention to the appropriate operational personnel whenever a new alarm is generated, or when an existing alarm condition returns to normal. Thus, operators are not required to manually determine which operator is responsible for the alarm. 
     An alarm distribution indication system provides a single display page on a video display unit from which operators can conveniently ascertain the overall alarm state and alarm distribution. Thus, operators do not have to mentally construct an overview of the overall alarm state and distribution by examining and filtering various alarm lists. 
     Additionally, a device for selectively displaying a plurality of alarms allows operators to conveniently and rapidly access one or more alarms based on a desired contextual view. Thus, operators do not have to manually search through a display menu to select a desired mimic display or manually recall the appropriate alarm list. 
     These and other features and advantages of the present invention will become more apparent to those skilled in the art when the following detailed description is read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic representation of an alarm management system according to the preferred embodiment of the present invention. 
     FIG. 2 depicts a display page showing an alarm status overview that may be viewed on a workstation video display unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The alarm management system  10 , depicted schematically in FIG. 1, receives signals from one or more sensors  12 . The sensors  12  provide signals indicative of various process parameters within the industrial facility into which the system  10  is installed. In this regard, the term process parameter refers to physical parameters, such as temperature, pressure, flow rates, etc., and also refers to plant component status, such as valve positions, pump rotation speeds, vibration levels, etc. The skilled artisan will appreciate that the number of process parameters, and the specific physical parameters and component statuses, will vary according the application with which the alarm management system  10  is being used. The skilled artisan will further appreciate that various types of sensors known in the art may be used with the present invention. 
     The signals provided from each sensor  12  are transmitted to a data acquisition system  14 , which may be any conventional data acquisition system known in the art. The sensor data is then transmitted from the data acquisition system to a digital computer  16 . The digital computer  16  may be a personal computer (PC), a plurality of networked computers, or a main frame computer. 
     A plurality of alarm video display units  26  are located at operator workstations to display alarm information to operators. The number of alarm video display units  26  will depend upon the number of operators necessary for the particular plant. However, in the preferred embodiment, for a nuclear power plant, the number of workstations and alarm video display units  26  is two, one for the reactor operator and one for the turbine operator. Each operator workstation also includes an operator input device  28 , which allows the workstation operator to interface with the digital computer  16 . The operator input device  28  may be a trackball, a computer mouse, a touch-screen, a finger-pad, or any other device known to the skilled artisan. The operator input device  28  is used to acknowledge new alarms and clear alarms that have returned to normal. The operator input device  28  is also used to transmit a “link request,” discussed further below, to selectively display the alarms in a particular format on the associated alarm video display unit  26 . The alarm video display units  26  and operator input devices are connected to the computer  16  via a network connection  15 . The network connection  15  may a dedicated network connection or shared with other systems. 
     Several modules within the computer  16  interact to achieve the desired functionality of the present invention. These modules may be separately designed individual hardware modules, conventional hardware modules programmed to perform specified functions, or may represent software modules which cause the digital computer  16  to perform each of the specified functions. The modules may be grouped into three main subsystems, all of which interact directly or indirectly with an alarm processing module  18 . These subsystems shown using dotted lines in FIG. 1, are a directive annunciator subsystem  30 , an alarm distribution overview indicator subsystem  40 , and an alarm view linker subsystem  50 . It should be noted that the alarm video display units  26  and operator input devices  28 , which are located at each workstation, are common to both the alarm distribution overview indicator subsystem  40  and the alarm view linker subsystem  50 . It should further be noted that these subsystems share certain functional modules and information when integrated together into a system, though each are described herein as separate subsystems. These facts will become apparent from the description of each of these subsystems provided below. It will be further appreciated by the skilled artisan that each of these subsystems could be utilized alone, or in any desired combination, to achieve a desired functional result. In the following description, a description of the operation of the alarm processing module  18  will be provided, followed by a detailed description of each of the subsystems. 
     Alarm Processing Module 
     The alarm processing module  18  compares the sensor data received from the data acquisition system  14  to associated alarm setpoints and generates appropriate alarm status signals on the basis of the comparison. The particular alarm status signal generated by the alarm processing module  18  will depend upon whether a datum exceeds a setpoint (a new alarm condition), or a datum that previously exceeded a setpoint is now below the setpoint (a return-to-normal condition). The alarm status signal generated by the alarm processing module  18  also includes various types of classification information to assist operators. This information includes the alarm priority classification, the operational responsibility classification, and the plant system classification. 
     The priority classification information alerts the operator (or operators) to the relative importance of the alarm. Thus, an operator can readily distinguish between relatively important and unimportant alarms, and thereby prioritize recovery actions to minimize operational impact. The number of priority classifications can be varied to suit the particular use, but in the nuclear power generation context, the preferred number of priority classifications is three. In this respect, the priority classifications are labeled “Priority  1 ,” “Priority  2 ,” and “Priority  3 .” 
     Priority  1  alarms are the last, and sometimes only, warning prior to reaching a “Significant Operator Action” condition. These alarms are generally related to the safety and availability of the plant, and include conditions associated with violations of critical reactor safety functions. If such conditions are not corrected immediately, a plant shutdown (manual or automatic), a radioactive release, or major equipment damage, will result. 
     Priority  2  alarms are the next to last warning prior to reaching a “Significant Operator Action” condition. These alarms include conditions associated with plant technical specification violations that, if not corrected, will result in an eventual plant shutdown, or an eventual radioactive release. Priority  3  alarms are warnings prior to the next to the last warning before reaching a “Significant Operator Action” condition. If no significant operator action can result, these alarms are the only warning. 
     Priority  3  alarms include conditions that, if left unattended, could result in a subsequent higher priority alarm condition. Such conditions typically indicate equipment or process anomalies. 
     The operational responsibility classification indicates which operator is responsible to process the alarm. The number of operational classifications can also include any number necessary to meet the requirements of the environment in which the system is being employed. In the nuclear power generation context, however, the preferred number of operational responsibility classifications is two. These classifications are the reactor operator (RO) classification and the turbine operator (TO) classification. Thus, an alarm in the RO classification indicates that the reactor operator is responsible to process the alarm, and an alarm in the TO classification indicates that the turbine operator is responsible. 
     The plant system classification indicates which plant system the alarm is associated with. Again, the number of system classifications can vary with the application. In the nuclear power generation context, the plant system classification would include, for example, the Chemical and Volume Control System, Reactor Coolant Pumps, Reactor Core, Main Feedwater System, Auxiliary Feedwater System, etc. 
     The alarm processing module  18  also includes logic to suppress temporary alarms that occur due to plant transients or other momentary disturbances. These temporary alarms are not necessary for safe operation and are considered to be nuisance alarms since they do not reflect actual process parameter abnormalities. 
     Directive Annunciator Subsystem 
     The directive annunciator subsystem  30  is comprised of an annunciator logic module  32 , a tone generator  34 , a speech synthesizer  36 , and a speaker  38 . The directive annunciator subsystem  30  interacts with other components and subsystems to provide audio notification of new alarm conditions, and return-to-normal conditions. The audio notification also provides appropriate operator responsibility classification information to operators. 
     Specifically, whenever the alarm processing module  18  determines that a new alarm condition or a return-to-normal condition exists, the alarm processing module  18  sends an updated alarm status signal to the annunciator logic module  32 . The annunciator logic module  32  receives the alarm status signal, and the information contained therein, to determine an appropriate audio output command for the specific condition. The appropriate audio output command is sent to both the tone generator  34  and the speech synthesizer  36 , via the network  15 . 
     The tone generator  34  produces a plurality of alarm tones of differing frequencies to alert the operator to a new alarm condition, a return-to-normal condition, or to alert the operator that a new alarm has not been acknowledged. The speech synthesizer  36  generates voice messages to direct attention to the proper operational responsibility for both a new alarm condition and a return-to-normal condition. As with the tone generator  34 , voice messages of differing frequencies are used to differentiate between the operational responsibility for the alarm. The voice frequencies generated by the speech synthesizer  36  can be selected based on the desired effect and number of differing operational responsibility categories. In the preferred embodiment, however, where the system is used in a nuclear power plant, two different voice frequencies are used. A substantially male sounding voice is used for reactor operator responsibility alarms, and a substantially female sounding voice is used for turbine operator responsibility alarms. The operation of the directive annunciator subsystem will be explained below for various exemplary conditions. 
     If the alarm processing module  18  determines that a new alarm condition exists, it sends an appropriate signal to the annunciator logic module  32 . The annunciator logic module  32  then sends appropriate commands the tone generator  34  and the speech synthesizer  36 . The tone generator  34  then generates a momentary tone (e.g., approximately 1 second in duration), to alert the operators to the new alarm condition. Immediately thereafter, the speech synthesizer  36  generates an appropriate sounding voice message directed to the appropriate operator. In the preferred embodiment, if the responsible operator is the reactor operator, the voice message would be a substantially male sounding voice stating, “New reactor alarm(s).” If the responsible operator is the turbine operator, the voice message would be a substantially female sounding voice stating, “New turbine alarm(s).” Moreover, if several new alarms occur simultaneously, some being the reactor operator&#39;s responsibility and some being the turbine operator&#39;s responsibility, the voice message would state, “New reactor alarm(s) and new turbine alarm(s).” In this instance, a substanatially male sounding voice is used for the former part of the message (e.g., “New reactor alarm(s)”), and a substantially female sounding voice for the latter part (e.g., “and new turbine alarm(s).”). 
     Upon receipt of the tone and voice message, the appropriate operator can then view the alarm(s) on the associated alarm video display unit  26 , and use the operator input device  28  associated with the workstation to acknowledge the alarm. The operator can then take appropriate action. When the operator acknowledges the new alarm using the operator input device  28 , the alarm information in the current alarm file  42  is updated to reflect this acknowledgement. 
     If the alarm processing module  18  determines that one or more return-to-normal conditions exist, it sends an appropriate signal to the annunciator logic module  32 . The annunciator logic module  32  in turn commands the tone generator  34  and speech synthesizer  36  to generate an appropriate tone followed by an appropriate voice message, respectively. Specifically, a tone different from the new alarm condition tone is momentarily generated (e.g., for approximately 1 second) by the tone generator  34 . Then, the voice synthesizer  36  outputs a voice message of appropriate frequency. For instance, in the preferred embodiment of the invention, if the return-to-normal condition is associated with a reactor operator responsibility alarm, the voice message would be a substantially male sounding voice stating, “Cleared reactor alarm(s).” Likewise, if the return-to-normal condition is associated with a turbine operator responsibility alarm, the voice message would be a substantially female sounding voice stating, “Cleared turbine alarm(s).” Finally, if the return-to-normal condition is associated with a plurality of alarms, some being associated with the reactor operator&#39;s responsibility and some being associated with the turbine operator&#39;s responsibility, the voice message would state, “Cleared reactor alarm(s) and cleared turbine alarm(s).” Again, in this instance a substanatially male sounding voice is used for the former part of the message (e.g., “Cleared reactor alarm(s)”), and a substantially female sounding voice for the latter part (e.g., “and cleared turbine alarm(s).”). 
     Upon receipt of the tone and voice message, the appropriate operator can then use the operator input device  28  associated with the workstation to clear the alarm. When the operator clears the alarm, the alarm information in the current alarm file  42  is updated to reflect that it is cleared. 
     As noted above, upon receipt of a new alarm condition or a return-to-normal condition, as appropriately annunciated by the new alarm tone and voice message, the operator uses the operator input device  28  to acknowledge the alarm or the return-to-normal condition. If either condition is not acknowledged within a predetermined period of time, the directive annunciator subsystem  30  provides a reminder notification to the operator. 
     To generate the reminder notification, the alarm processing module  18  periodically scans the information in the current alarm file  42  to determine if any alarm conditons have not been acknowledged or return-to-normal conditions have not been cleared. If either of these conditions exists, the alarm processing module  18  directs an appropriate alarm status signal to the annunciator logic module  32 . The annunciator logic module  32  then commands the tone generator  34  and voice synthesizer  36  to generate an appropriate tone and voice message, respectively. Specifically, a momentary tone having a unique frequency, would be followed immediately by an appropriate voice message. For instance, in the preferred embodiment, for unacknowledged alarms or uncleared (return-to-normal) conditions associated with reactor operator responsibility, the voice message would state, “Unacknowledged (Uncleared) reactor alarm(s).” For unacknowledged alarms or uncleared (return-to-normal) conditions associated with turbine operator responsibility, the voice message would state, “Unacknowledged (Uncleared) turbine alarm(s).” And, for a plurality of unacknowledged (uncleared) alarms, some being associated with the reactor operator&#39;s responsibility and some being associated with the turbine operator&#39;s responsibility, the voice message would state, “Unacknowledged (Uncleared) reactor alarm(s) and unacknowledged (uncleared) turbine alarm(s).” Once again, in this instance a substanatially male sounding voice is used for the former part of the message (e.g., “Unacknowledged (Uncleared) reactor alarm(s)”), and a substantially female sounding voice for the latter (e.g., “and unacknowledged (uncleared) turbine alarm(s).”). 
     If new alarms occur before a previous alarm is acknowledged, the new alarm will be initially annunciated with the appropriate tone and voice message. The reminder tone will be periodically output thereafter until all unacknowledged alarms have been acknowledged. The similar function occurs if new return-to-normal conditions occur before previous ones are cleared. 
     Alarm Distribution Overview Indicator 
     The alarm distribution overview indicator subsystem  40  comprises the current alarm file  42 , an alarm status overview module  44 , and one or more alarm video display units  26 . The alarm distribution overview indicator subsystem  40  interacts with other subsystem modules to provide a coherent status overview of overall alarm status. In other words, how the alarms are distributed. This function of this subsystem will now be described. 
     The alarm status overview module  44  periodically searches through the alarm information stored in the current alarm file  42 . The search periodicity is not critical to the inventive concept, but in the preferred embodiment it is approximately every second. The stored information includes the alarm status information (e.g., whether the alarm is new; whether the alarm, if new, has been acknowledged; and whether the alarm has returned-to-normal). And, as discussed previously, the stored information also includes the information associated with the each alarm&#39;s priority classification, operational responsibility classification, and plant system classification. The alarm status overview module  44 , during the search period, extracts the information and arranges it according to both its status and classification. The information so arranged by the alarm status overview module  44  is then sent to one or more of the alarm video display units  26 . 
     An exemplary display page  60  view of the alarm status overview that a alarm video display unit  26  would provide is illustrated in FIG.  2 . An operator viewing this display page  60  is presented with an overall alarm distribution summary, according to each alarm&#39;s status and its specific operational responsibility (or “Work Scope”), alarm priority, and system classifications. Thus, within each of the specific classifications, the display page  60  depicts the number of alarms that are new, acknowledged, and returned-to-normal. The display page  60  also depicts the total number of alarms that are new, acknowledged, and returned-to-normal. 
     As shown in the right-hand portion of FIG. 2, the display page  60  also depicts various links  62 . These links  62  are used with the alarm view linker subsystem  50 . The alarm view linker subsystem  50  interacts with other subsystem modules and allows an operator to directly link, from the display page  60 , to a desired alarm view. Thus, the operator can view alarm information from various perspectives. Specifically, the operator can view the alarms from a system mimic diagram display perspective, or an alarm list perspective. 
     Alarm View Linker 
     The alarm view linker subsystem  50  comprises a link module  52 , an alarm list generator module  54 , a VDU display set module  56 , and one or more workstation alarm video display units  26  and associated operator input devices  28 . Using the operator input device  28 , an operator makes a “link request” for a specific alarm view by designating the appropriate link  62 . For example, if the operator input device  28  is a touch-screen, and the operator wishes to view a list of alarms having a Priority I classification, the operator would touch the display page  60  at the link  62  displaying “P- 1 .” Or, if the operator wishes to view alarms associated with a particular system on a system mimic diagram, the operator would touch the display page at the link  62  under the Mimic Display column displaying the particular system designation. The link module  52  recognizes the link request made by the operator, via the operator input device  28 , and outputs the appropriate view, either a list or system mimic diagram display, to the associated alarm video display unit  26 . The link module  52  retrieves the desired information for display from the alarm list generator module  54  for alarm list display links, or from the VDU display set module  56  for system mimic diagram display links. 
     The alarm list generator module  54  periodically retrieves the alarm information stored in the current alarm file  42  and generates a series of lists. Each list contains a chronological listing of each alarm within the selected alarm list classification, and includes specific and detailed information about the alarm condition. More specifically, the alarm list generator module  54  generates separate lists for each operational responsibility classification, each priority classification, each system classification, and a total alarm list. For example, according to the preferred embodiment, wherein the system is installed in a nuclear power plant, the alarm list generator module  54  generates the following lists: RO Alarm List, TO Alarm List, ALL Alarm List, Priority  1  Alarm List, Priority  2  Alarm List, Priority  3  Alarm List, and various SYSTEM Alarm Lists. 
     The RO and TO Alarm Lists contain, respectively, a chronological listing of all RO and TO alarms (both new and acknowledged) and RO and TO alarms that have returned-to-normal (but not yet cleared). These lists can be further filtered, via the operator input device  28 , to indicate, respectively, only the new (unacknowledged) RO and TO alarms, only the RO and TO alarms that have returned-to-normal but have not been cleared, or only the RO and TO alarms that have returned-to-normal by alarm priority level. With the latter filtration, Priority  1  alarms are listed first in their chronological order of occurrence, followed concomitantly by Priority  2  alarms then Priority  3  alarms. It should be noted that this filtration scheme is not limiting and other filtration schemes can be used to display various subsets of the RO and TO alarm lists. 
     The ALL Alarm List contains alarm information similar to that described for the individual RO and TO alarm lists, including the specified filtration scheme. However, this list contains the total number of alarms, regardless of operational responsibility. 
     The Priority  1 ,  2 , and  3  Alarm Lists contain, respectively, a chronological listing of all Priority  1 ,  2 , and  3  alarms (new and unacknowledged) and Priority  1 ,  2 , and  3  alarms that have returned-to-normal, regardless of operational responsibility. These lists may be further filtered, via the operator input device  28 , to indicate, respectively, the Priority  1 ,  2 , and  3  alarms associated with either the RO and/or the TO. 
     The SYSTEM Alarm Lists each contain a chronological listing of all alarms associated with a particular system. Since each system is typically associated with either the RO or the TO, the operational responsibility information is inherently contained within each list. However, certain systems do have alarms that fall under the operational responsibility of both the RO and TO. For such systems, the particular SYSTEM Alarm List may be further filtered accordingly. 
     The VDU display set module  56  stores all of the mimic diagram displays associated with each system. The system mimic diagram displays are organized in a hierarchical order, and contain alarm information graphically depicted in the context of plant systems, components, and processes. Similar to the alarm list generator module  54 , the VDU display set module  56  periodically retrieves the alarm information from the current alarm list module  42 , and updates the mimic diagram displays accordingly. 
     The VDU display set module  56  includes color coding, shape coding, and dynamic behavior (such as blinking) to indicate the presence of alarms and to indicate the alarm state (i.e., new alarms, acknowledged alarms, returned-to-normal alarms). For example, alarms that appear on a system mimic diagram display as an alphanumeric value will change from a “normal value” color to the “alarm value” color at the point in the system mimic diagram where the alarming parameter is being monitored. If the specified alarm has a dynamic alarm behavior associated with it, such as blinking, this behavior will also be depicted on the system mimic diagram display. Additionally, if a particular component in a system is controlled when an alarm condition occurs, such as a pump or a valve, the component symbol on the system mimic diagram display will be depicted with the appropriate alarm condition color, shape, and/or dynamic behavior. 
     While preferred embodiments of the present invention have been illustrated in detail, it is apparent that modifications and adaptations of the preferred embodiments will occur to those skilled in the art. However, it will be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims.