Power Distribution Panel

A Power Distribution Panel (also known as a CCR distribution panel or main distribution board) is the central hub that routes electrical power from the airport's main supply (typically 415V AC, 3-phase) to individual Constant Current Regulators (CCRs) and other AGL power equipment. It houses main incoming breakers, busbars, outgoing circuit breakers or MCCBs, monitoring instruments, and often surge protection devices.

The panel provides safe and reliable power distribution, allowing maintenance staff to isolate individual CCRs or circuits for servicing without affecting the entire AGL system. It may also include automatic transfer switches (ATS) for backup generator integration and power quality monitoring to ensure stable operation of the AGL lighting systems.

The distribution panel exists to let individual CCRs and circuits be isolated, serviced, or replaced without shutting down the entire AGL power supply, a capability that matters enormously in an environment where the airfield can rarely afford to take all lighting circuits offline for routine maintenance. By centralizing incoming supply, protection devices, and outgoing circuits into one coordinated hub rather than wiring each CCR directly to the mains independently, the panel makes fault isolation, load management, and future circuit additions dramatically simpler than they would be with an unstructured, ad hoc distribution scheme. Its role as the integration point for automatic transfer switches and power quality monitoring reflects the same underlying purpose: giving a single, well-organized location where the health and configuration of the entire AGL electrical supply can be managed and observed.

Power Distribution Panels are installed in central electrical rooms, equipment shelters, or dedicated AGL power buildings located on the airfield. They are used in:

• Main AGL Power Centers: Distributing power to all CCRs that feed runway, taxiway, and approach lighting circuits.
• Remote Equipment Huts: Smaller distribution panels for decentralised CCR installations located near the airfield perimeter.
• Backup Power Integration: Panels with automatic transfer switches to seamlessly switch between utility and generator power during outages.
• Load Shedding and Prioritization: Panels equipped with contactors to shed non-critical loads during peak demand or generator operation.
• Integration with ALCMS: Panels with communication modules that report status, current draw, and alarms to the central ALCMS.

The panel is floor-standing in the main AGL power centre, positioned close to the incoming utility or generator switchgear so the main busbar run stays short, with outgoing ways fanning out to the CCRs, UPS, and other loads it serves. Smaller decentralised panels for remote equipment huts are wall-mounted in a weatherproof outdoor enclosure where the site has no dedicated power building. Incoming and outgoing cables enter through a gland plate at the top or bottom depending on the cable route (overhead tray or underground duct), and the panel frame and busbar earth link are bonded to the site earthing system. Clearance is maintained at the front for breaker operation and metering access, and at the rear where rear-access wiring is used, per the enclosure's IP rating.

The panel receives main power from the utility transformer or generator switchgear via a main incoming circuit breaker or MCCB. This power feeds a common busbar system (typically copper) that distributes to multiple outgoing branch circuits. Each branch circuit is protected by a dedicated MCCB or circuit breaker and supplies a single CCR or group of CCRs.

Key functional elements include:

• Main Incoming Section: Includes the main isolation switch, main circuit breaker, and metering for total system current, voltage, and power.
• Busbar System: High-conductivity copper bars that distribute power to all outgoing circuits, rated for the total system load.
• Outgoing Branch Circuits: Individual MCCBs or breakers for each CCR, with auxiliary contacts for status monitoring and remote control.
• Surge Protection: Surge arresters and transient voltage suppressors to protect sensitive CCR electronics from lightning-induced surges.
• Monitoring and Control: Digital multimeters, current transducers, and communication modules (Modbus, Ethernet) that provide real-time data to the ALCMS.
• Automatic Transfer Switch (optional): For installations with backup generators, an ATS automatically switches between utility and generator power upon mains failure.

Control in the PDP is layered rather than centralised: most of it is simple electromechanical protection, with a thin layer of remote monitoring and (optionally) automatic switching on top. The main incoming breaker and each branch MCCB trip purely on overcurrent/fault condition — that logic is local to the breaker and needs no communication link to act. Auxiliary contacts fitted to the main breaker and each branch report open/closed status and, on some installations, allow remote trip/close commands; those signals, together with current transducers and digital metering on the busbar, feed a communications module (typically Modbus or Ethernet) that reports real-time voltage, current, and breaker status to the ALCMS — the ALCMS can see the state of every branch and, where fitted, command it, but it isn't in the path of the protection itself. Where a standby generator is installed, the Automatic Transfer Switch runs its own independent logic: it monitors utility supply quality continuously and switches the busbar to generator power on mains failure without waiting for or depending on the ALCMS link, then switches back once utility supply is confirmed stable. Surge protection devices sit passively across the busbar and act instantaneously on transient overvoltage, again with no communication dependency. The result is a panel that keeps functioning and protecting its downstream CCRs even if the monitoring link to the ALCMS is down — remote visibility and control are an add-on layer, not a dependency for the panel's core switching and protection.

The Power Distribution Panel is built as a floor-standing or wall-mounted steel cabinet or switchboard, powder-coated and fitted with lockable, hinged doors for safe access to live busbars and breakers. Internally, tinned-copper busbars run the length of the panel, fed from a main incoming circuit breaker or isolator, with outgoing MCCBs or MCBs for each CCR or distribution circuit mounted in rows and clearly labelled. Instrumentation — ammeters, voltmeters, or a digital power meter — is typically mounted on the door or a dedicated instrument panel, along with indicator lamps for each circuit's status. Surge protection devices are fitted at the incoming supply, and where an ATS is integrated, the transfer switchgear occupies a separate compartment within the same cabinet or an adjacent enclosure. Cable entry is via a gland plate or cable ladder at the top or base, and an earthing bar runs the width of the panel for bonding all outgoing circuits.