What is series circuit architecture?
How a series lighting system is organised — control and CCR as the source, one cable loop, and an isolation transformer and fixture for every light.
The architecture of an AGL series circuit has three layers. The source is the CCR with its control, which holds the current at the chosen brightness step. The distribution is the primary cable, laid as a single loop out across the airfield and back. The load is an isolation transformer and a fixture for each light, connected into the loop.
An airfield has many such circuits, usually one or more for each lighting system, each sized to a CCR. Alternate fixtures are sometimes put on different circuits (interleaving) so that a single circuit failure thins a row of lights instead of blanking it. The behaviour of the loop is covered under constant-current circuit and series circuit current path.
- Group. Divide the lights into circuits by lighting system and CCR rating.
- Place the CCR. Locate it in the equipment room or substation.
- Lay the loop. Run the primary cable out across the airfield and back.
- Connect transformers. Put one isolation transformer for each fixture or sign into the loop.
- Connect fixtures. Each fixture takes its supply from its transformer secondary.
- Connect control. Link the control so the brightness step can be selected.
Frequently Asked Questions
Q1What is the architecture of an AGL series circuit?
It is the way the parts are arranged: a CCR with its control as the source, a primary cable laid as one loop out and back, and an isolation transformer and fixture for each light connected into that loop.
Q2What are the main parts and what does each do?
The control selects the brightness step. The CCR holds the loop current at that step's value. The primary cable carries the current around the loop. Each isolation transformer connects one fixture to the loop, and the fixture gives the light.
Q3Why does each light have an isolation transformer?
It keeps the lamp side separate from the high voltage on the loop and passes power to the lamp by induction. It also helps the loop stay complete if a lamp fails.
Q4How many circuits does an airfield have?
Usually many. Each lighting system, such as runway edge, centreline or taxiway lights, is generally put on its own circuit or circuits, sized to the rating of a CCR, so the number depends on the size and layout of the airfield.
Q5Why are alternate fixtures sometimes put on different circuits?
This is called interleaving. If one circuit fails, the lights on the other circuit stay lit, so a row of lights is thinned out rather than lost completely.
Q6Where are the CCRs placed?
Normally in an equipment room or substation, from where the primary cable loops run out across the airfield and back. See CCR location for how the position is chosen.
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