What is standby power and a UPS?
A second source and a battery backup that keep the lights and the control system running when the primary supply fails.
Standby power is a second source that keeps essential airfield lighting and its control system running when the primary supply fails. It is usually an engine generator brought on by a changeover switch, sometimes with a second utility feed or batteries. A UPS is a battery-backed supply that carries equipment through the short break while the standby source starts and the changeover completes. ICAO Annex 14 Volume I covers secondary power supplies for aerodrome visual aids, and how quickly the supply must be restored depends on the facility.
The regulators are large loads, so after changeover they are normally carried by the generator. The UPS is typically sized for the control and monitoring equipment, such as the ALCMS, controllers and communications, so they do not drop out or reset during the break. A generator that does not start, a flat or ageing battery, or a changeover that sticks turns a power cut into a dark airfield, and these faults are often found only in a real outage.
- Detect. The loss or poor quality of the primary supply is sensed.
- Start. The standby generator starts and comes up to voltage and frequency.
- Changeover. The switch moves the load to the standby source once it is ready.
- Bridge. The UPS carries the control and monitoring equipment through the break.
- Restore. When the primary supply is back and stable, the load is transferred back.
- Test & record. Run the generator on load, test the changeover, check batteries and fuel, and log the results.
Frequently Asked Questions
Q1What is standby power for airfield lighting?
Standby power is a second source that keeps essential airfield lighting and its control system running when the primary supply fails. It is usually an engine generator, brought on by a changeover switch, and sometimes a second utility feed or batteries. ICAO Annex 14 Volume I covers secondary power supplies for aerodrome visual aids.
Q2What does a UPS do in an airfield lighting system?
A UPS is a battery-backed supply that carries equipment through a short break in power. In an airfield lighting system it typically protects control and monitoring equipment, such as the ALCMS, controllers and communications, so they do not drop out or reset while the generator starts and the changeover completes.
Q3Are the regulators powered from the UPS?
Normally the regulators are large loads and are carried by the standby generator after changeover, while the UPS is sized for control and monitoring equipment. The design depends on the project and the authority's requirement, so check the electrical design.
Q4How is standby power tested?
By running the generator on load, testing the changeover, checking the UPS batteries and the fuel, and recording the results. Test the whole chain, from detecting the loss of supply to the lights staying on, and follow the manufacturer's manuals and the authority's requirements.
Q5What goes wrong with standby power?
The generator fails to start or runs out of fuel, UPS batteries are flat or too old, the changeover switch sticks or is left in the wrong position, or the system has never been tested on load. These faults are often found only during a real outage, so test regularly.
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