Alarm Panel

An Alarm Panel (also known as an Annunciator Panel or Alarm Annunciator) is a dedicated hardware and software interface that provides visual and audible indication of abnormal conditions within the AGL system. It is typically installed in CCR control rooms, ATC towers, or maintenance offices, where operators need immediate awareness of faults. The panel consolidates alarms from all AGL subsystems—CCRs, lighting circuits, power supplies, communication networks, and field devices—and presents them in a clear, prioritised manner. Alarms are typically categorised by severity (critical, major, minor, warning) and displayed with a flashing LED, alphanumeric message, and audible buzzer/siren. The panel also provides acknowledgment, silence, and reset functions, and often includes a historical log of alarm events. The Alarm Panel is a vital safety component, ensuring that operators are alerted to conditions such as circuit failures, overcurrent, lamp outages, communication loss, or power supply issues that could compromise airfield safety.

The alarm panel exists because a fault in the AGL system — a failed circuit, a lamp outage, a lost communication link — is only useful information if a human operator actually notices it in time to act. Without a consolidated, prioritised alarm presentation, a fault buried in one of dozens of subsystems could go unnoticed until it affects a live approach or departure, at which point the response is reactive rather than preventive.

By flashing, sounding, and prioritising alarms by severity, the panel makes sure a critical fault — one with immediate safety implications — can't be lost among routine warnings, giving operators a clear, unambiguous cue for when a lighting circuit needs urgent attention versus when an issue can be scheduled for later maintenance. This triage function is what turns raw fault data into an actionable operational picture.

Alarm Panels are deployed in critical locations where immediate notification of AGL faults is essential:

• CCR Control Rooms: Primary alarm annunciation for all lighting circuits and power supplies, with audible and visual alerts to operators.
• ATC Towers: Providing tower controllers with immediate notification of lighting failures that could affect aircraft operations.
• Maintenance Shops: Alerting maintenance staff to faults requiring field intervention, with details of the affected circuit or equipment.
• Remote Substations: Local panels at substations to indicate faults specific to that location, facilitating rapid local response.
• Airport Operations Centers: Integration with central operations for overall situational awareness of airfield status.
• Fire & Rescue Stations: Providing alarm status for emergency lighting circuits and runway status lights.
• Approach Lighting Control Shelters: Dedicated panels for approach lighting sequencer and strobe power supply alarms.

Panels are wall- or rack-mounted inside the CCR control room, substation, or ATC tower equipment space they serve, positioned within easy sightline and reach of the operator position rather than tucked behind other equipment. Input wiring from field alarm contacts and monitoring points is home-run to the panel's terminal rack, kept on screened cable where it runs alongside power cabling to avoid induced nuisance alarms; panels intended for 24-hour-manned locations are sited so the audible alarm is clearly heard over ambient room noise. Where a panel duplicates alarms already available on an ALCMS workstation, its cabling is still independent of the network connection so it continues to function during a network or server outage.

The Alarm Panel operates as a dedicated fault annunciation system, performing several key functions to ensure operators are promptly and accurately informed:

• Alarm Acquisition: The panel receives alarm signals from the ALCMS server, PLCs, or Remote I/O units via communication links (Ethernet, serial, or hardwired contacts). Each alarm is associated with a specific point (circuit, CCR, sensor) and has a predefined severity level.
• Visual Indication: Alarms are displayed using high-visibility LEDs or a graphical LCD screen. Typically, a flashing red LED indicates a critical alarm, flashing amber for major, steady amber for minor, and flashing green for warnings or acknowledgments. The message area displays the alarm description, location, and timestamp.
• Audible Alerts: A built-in buzzer or external siren sounds when a new alarm occurs. The audible tone may vary by severity (e.g., continuous for critical, intermittent for minor).
• Acknowledgment & Silence: Operators can press an "Acknowledge" button to stop the audible sound and change the visual state from flashing to steady (indicating the alarm has been seen). A "Silence" button may allow temporary muting while the alarm remains active.
• Alarm Logging: The panel stores a history of alarms with time-stamps, status changes (active, acknowledged, cleared), and operator actions for audit and troubleshooting.
• Self-Supervision: The panel monitors its own health (communication, power, internal diagnostic) and provides a "panel healthy" indication to ensure operators know the panel itself is functioning.
• Remote Reporting: Some panels can forward alarms to a central SCADA system or send SMS/email notifications to maintenance personnel.

Alarm Panels are typically configured using dedicated engineering software, where each alarm point is defined with a message, severity, and priority class. They are designed for high reliability and low maintenance, often with redundant power supplies and isolated inputs.

Inside the alarm panel, incoming signals from field devices — lighting circuit fault contacts, CCR status contacts, SPD status contacts, and communication-loss signals — are terminated on input modules that convert each contact or analog/digital signal into a normalized alarm state. A central logic controller polls or receives these states, applies prioritization rules (higher-priority alarms pre-empt lower-priority faults) and any programmed zone or cause-and-effect logic, then drives the output stage: audible/visual annunciators locally, and relay or network outputs to the ALCMS, a remote monitoring centre, or (where the panel also carries emergency lighting circuit status) a fire and rescue station. Every state change is timestamped and written to the event log, and the panel continuously self-monitors its own power supply, battery backup and field wiring, reporting a system trouble condition distinct from a genuine field alarm if its own health check fails.

The alarm panel is built into a steel or composite enclosure sized for panel-mount or field-mount installation, with the front bezel housing the LED indicator matrix or graphical LCD, audible buzzer, and any local acknowledge/silence controls behind a sealed, gasketed front face rated IP65/NEMA 4X. The rear of the enclosure carries terminal blocks and connector strips for the hardwired dry-contact inputs, serial and Ethernet communication ports, and the power supply connection, typically protected to a lower IP20 rating appropriate for a controlled cabinet or back-of-panel environment, or upgraded to IP65 for field-mount applications exposed to the elements. Internally, the logic board, communication interfaces, and power supply are mounted on standoffs with clear separation between low-voltage signal wiring and mains or 24VDC power distribution to limit electromagnetic interference. A non-volatile event log memory retains alarm history through power loss, and the enclosure's mounting flanges or DIN-rail clips allow secure installation in equipment racks, control rooms, or outdoor cabinets.