Annunciator panel
Encyclopedia
An annunciator panel is a group of lights used as a central indicator of status of equipment or systems in an aircraft, industrial process, building or other installation. Usually the annunciator panel includes a main warning lamp or audible signal to draw the attention of operating personnel to the annunciator panel for abnormal events or conditions.
, annunciator panels are groupings of annunciator lights that indicate status of the aircraft's subsystems. The lights are usually accompanied with a test switch, which when pressed illuminates all the lights to confirm they are in working order. More advanced modern aircraft replaces these with the integrated electronic Engine Indicating and Crew Alerting System or Electronic Centralised Aircraft Monitor.
On this aircraft overhead panel, the pilot is pressing the test switch. You can also see how the lights are grouped together with their associated systems into various panels of lights.
The following colours are normally utilised with the following meanings:
On occasion, the annunciator panel will display warnings or cautions that are not necessarily indicative of a problem; for example, a Cessna 172
on its after-landing roll will often flicker the "Volts" warning simply due to the idle throttle
position and therefore the lower voltage output of the alternator
to the aircraft's electrical system.
More complicated aircraft will feature "Master Warning" and "Master Caution" lights/switches. In the event of any red or yellow annunciator being activated, the yellow or red master light, usually located elsewhere in the pilots line of sight will illuminate, in most installations they flash and an audible alert will accompany them. These "masters" will not stop flashing until they have been acknowledged, usually by pressing the light itself and in some cases the audible alert will also continue until this acknowledgement.
In this aircraft cockpit, the annunciator panel is clearly visible in the centre of the panel (just to the left and below the big red handle/lever), displaying a variety of warnings of differing severity. Directly below the windscreen area, on both the left and right side of the picture, is a large red light with a large yellow one below it. These are the master warning and master caution lights/switches.
, an annunciator panel is a system to alert operators of alarm conditions in the plant. Multiple back-lit windows are provided, each engraved with the name of a process alarm. Lamps in each window are controlled by hard-wired switches in the plant, arranged to operate when a process condition enters an abnormal state (such as high temperature, low pressure, loss of cooling water flow, or many others). Single point or multipoint alarm logic modules operate the window lights based on a preselected ISA 18.1 or custom sequence.
In one common alarm sequence, the light in a window will flash and a bell or horn will sound to attract the operator's attention when the alarm condition is detected. The operator can silence the alarm with a button, and the window will remain lit as long as the process is in the alarm state. When the alarm clears (process condition returns to normal), the lamps in the window go out.
Annunciator panels were relatively costly to install in a plant because they had dedicated wiring to the alarm initiating devices in the process plant. Since incandescent lamps were used, a lamp test button was always provided to allow early detection of failed lamps. Modern electronic distributed control system
s usually require less wiring since the process signals can be monitored within the control system, and the engraved windows are replaced by alaphanumeric displays on a computer monitor.
Behavior of alarm systems, and colors used to indicate alarms, are standardized. Standards such as ISA 18.1 or EN 60073 simplify purchase of systems and training of operators by giving standard alarm sequences.
This has left today a major obsolescence support problem for customers who are still using these Alarm Annunciator systems as part of their safety systems.
Over the last five years the Alarm Annunciator has seen a resurgence in popularity especially for use in IEC61508 SIL 1 and SHE (Safety Health and Environmental) alarm monitoring applications. The modern trend is to identify critical alarms and return them from the computer screen to discrete alarm windows. This is being done for two reasons. Firstly, alarm annunciators offer pattern recognition to the operators in the form of LED alarm fascias instead of just providing an exhaustive list of alarms and events which the operators have to scroll through and in some instances alarms can be overlooked. Secondly, the analysis of plant failure modes is leading to the separation of critical alarm monitoring and process control systems for safety reasons.
systems were considered the preferred alternative to discrete annunciators. A software-based solution, with almost endless ability to analyze, present and process alarms, has the potential for replacing discrete alarms switches altogether.
However, software carries its own reliability risks. Reliance on a software program to trigger an alarm assumes that the analog signal, the programmer's logic code and HMI, the PLC and/or PC running the programs, and the interaction between all of the above, are all entirely trustworthy. This is exacerbated by frequently changing computer hardware & firmware platforms and the need to modify existing software.
Aviation
In the aircraft industryAircraft industry
The aircraft industry is the industry supporting aviation by building aircraft and manufacturing aircraft parts for their maintenance. This includes aircraft and parts used for civil aviation and military aviation. Most production is done pursuant to type certificates and Defense Standards issued...
, annunciator panels are groupings of annunciator lights that indicate status of the aircraft's subsystems. The lights are usually accompanied with a test switch, which when pressed illuminates all the lights to confirm they are in working order. More advanced modern aircraft replaces these with the integrated electronic Engine Indicating and Crew Alerting System or Electronic Centralised Aircraft Monitor.
On this aircraft overhead panel, the pilot is pressing the test switch. You can also see how the lights are grouped together with their associated systems into various panels of lights.
The following colours are normally utilised with the following meanings:
- Red - Warning, this systems condition is critical and requires immediate attention (such as an engine fire, hydraulic pump failure)
- Orange/Yellow - Caution, this system requires timely attention or may do so in the future (ice detected, fuel imbalance)
- Green - Advisory/Indication, a system is in use or ready for operation (such as landing gearUndercarriageThe undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...
down and locked, APUAuxiliary power unitAn auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...
operating) - White/blue - Advisory/Indication, a system is in use (seatbelt signs on, anti-ice system in-use, landing lightsAircraft landing lightsLanding lights are lights used on aircraft to illuminate the terrain and runway ahead during takeoff and landing.-Overview:Almost all modern aircraft are equipped with landing lights if they are intended and approved for nighttime operations...
on)
On occasion, the annunciator panel will display warnings or cautions that are not necessarily indicative of a problem; for example, a Cessna 172
Cessna 172
The Cessna 172 Skyhawk is a four-seat, single-engine, high-wing fixed-wing aircraft. First flown in 1955 and still in production, more Cessna 172s have been built than any other aircraft.-Design and development:...
on its after-landing roll will often flicker the "Volts" warning simply due to the idle throttle
Throttle
A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...
position and therefore the lower voltage output of the alternator
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...
to the aircraft's electrical system.
More complicated aircraft will feature "Master Warning" and "Master Caution" lights/switches. In the event of any red or yellow annunciator being activated, the yellow or red master light, usually located elsewhere in the pilots line of sight will illuminate, in most installations they flash and an audible alert will accompany them. These "masters" will not stop flashing until they have been acknowledged, usually by pressing the light itself and in some cases the audible alert will also continue until this acknowledgement.
In this aircraft cockpit, the annunciator panel is clearly visible in the centre of the panel (just to the left and below the big red handle/lever), displaying a variety of warnings of differing severity. Directly below the windscreen area, on both the left and right side of the picture, is a large red light with a large yellow one below it. These are the master warning and master caution lights/switches.
Process control
In industrial process controlProcess control
Process control is a statistics and engineering discipline that deals with architectures, mechanisms and algorithms for maintaining the output of a specific process within a desired range...
, an annunciator panel is a system to alert operators of alarm conditions in the plant. Multiple back-lit windows are provided, each engraved with the name of a process alarm. Lamps in each window are controlled by hard-wired switches in the plant, arranged to operate when a process condition enters an abnormal state (such as high temperature, low pressure, loss of cooling water flow, or many others). Single point or multipoint alarm logic modules operate the window lights based on a preselected ISA 18.1 or custom sequence.
In one common alarm sequence, the light in a window will flash and a bell or horn will sound to attract the operator's attention when the alarm condition is detected. The operator can silence the alarm with a button, and the window will remain lit as long as the process is in the alarm state. When the alarm clears (process condition returns to normal), the lamps in the window go out.
Annunciator panels were relatively costly to install in a plant because they had dedicated wiring to the alarm initiating devices in the process plant. Since incandescent lamps were used, a lamp test button was always provided to allow early detection of failed lamps. Modern electronic distributed control system
Distributed control system
A distributed control system refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location but are distributed throughout the system with each component sub-system controlled by one or more...
s usually require less wiring since the process signals can be monitored within the control system, and the engraved windows are replaced by alaphanumeric displays on a computer monitor.
Behavior of alarm systems, and colors used to indicate alarms, are standardized. Standards such as ISA 18.1 or EN 60073 simplify purchase of systems and training of operators by giving standard alarm sequences.
Obsolescence and revival
The introduction of computer monitor based control systems during the 1980s and 1990s saw a wholesale absorption of alarm window displays on to the computer screen. This created a down-turn in the sales of the conventional Alarm Annunciator systems and many of the companies manufacturing these alarm annunciator products were either sold off or went out of business.This has left today a major obsolescence support problem for customers who are still using these Alarm Annunciator systems as part of their safety systems.
Over the last five years the Alarm Annunciator has seen a resurgence in popularity especially for use in IEC61508 SIL 1 and SHE (Safety Health and Environmental) alarm monitoring applications. The modern trend is to identify critical alarms and return them from the computer screen to discrete alarm windows. This is being done for two reasons. Firstly, alarm annunciators offer pattern recognition to the operators in the form of LED alarm fascias instead of just providing an exhaustive list of alarms and events which the operators have to scroll through and in some instances alarms can be overlooked. Secondly, the analysis of plant failure modes is leading to the separation of critical alarm monitoring and process control systems for safety reasons.
Discrete annunciators vs SCADA alarm systems
Some time ago SCADASCADA
SCADA generally refers to industrial control systems : computer systems that monitor and control industrial, infrastructure, or facility-based processes, as described below:...
systems were considered the preferred alternative to discrete annunciators. A software-based solution, with almost endless ability to analyze, present and process alarms, has the potential for replacing discrete alarms switches altogether.
However, software carries its own reliability risks. Reliance on a software program to trigger an alarm assumes that the analog signal, the programmer's logic code and HMI, the PLC and/or PC running the programs, and the interaction between all of the above, are all entirely trustworthy. This is exacerbated by frequently changing computer hardware & firmware platforms and the need to modify existing software.
Fire alarm panel
In large buildings, a central fire alarm annunciator panel is located where it is accessible to fire-fighting crews. The annunciator panel will indicate the zone and approximate physical location of the source of a fire alarm in the building. The annunciator will also include lamps and audible warning devices to indicate failures of alarm circuits. In a large building such as an office tower or hotel, the fire annunciator may also be associated with a control panel for building ventilation systems, and may also include emergency communication systems for the building.See also
- Acronyms and abbreviations in avionicsAcronyms and abbreviations in avionics-A:*ACARS: Aircraft Communications Addressing and Reporting System.*ACAS: Airborne Collision Avoidance System.*ACP: Audio Control Panel.*ACS: Audio Control System.*ADAHRS: Air Data and Attitude Heading Reference System.*ADC: Air Data Computer....
- Alarm managementAlarm managementAlarm management is the application of human factors along with instrumentation engineering and systems thinking to manage the design of an alarm system to increase its usability...
- Attendant consoleAttendant consoleAn attendant console is a telephone station that is generally part of a private branch exchange or Centrex or other private telephone system...
- BeaconBeaconA beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of...
- Idiot lightIdiot lightA tell-tale is an indicator of the status or malfunction of a system within a motor vehicle. Tell-tales consist of a light bulb or an LED which lights up a symbol or text legend...